This Podcast Will Kill You - Ep 128 Skin Cancer: We love and fear the sun

Episode Date: October 31, 2023

For every article about the risks of sun exposure or a guide to sunscreens, you don’t have to look far to find one about the health benefits of sunshine or a how-to for achieving the best tan. Messaging around sun exposure is mixed, to say the least, and it’s no wonder that despite having more sun protection tools than ever before, rates of skin cancer have never been higher. In this episode, we delve into the relationship between UV radiation and skin cancers, answering your (sun)burning questions about the different types of cancers and how sunscreens actually work. We then explore the history of sun protective methods and how attitudes around tanning have changed dramatically over time. We wrap up the episode with a look at rates of skin cancers around the globe today and exciting research showing the benefits of sunscreens as well as how AI might be used to help diagnose skin cancer. Tune in for an info-packed episode that will have you reaching for that sunscreen bottle. See omnystudio.com/listener for privacy information.

This is exactly right. There are already enough things charging your card every month. Dinner should not be one of them, which is exactly why Blue Apron is now subscription-free. You heard that right. Blue Apron no longer requires a subscription. You can order meals when you want them and skip when you don't without adding another recurring charge. Blue Apron meals are designed by chefs and arrive with pre-portioned ingredients, so there's no meal planning and no extra grocery trip. Order now at Blue Apron.com.

Get 50% off your first two orders plus free shipping with code this podcast 50. Terms and Conditions Apply. Visit blue apron.com slash terms for more information. Hello, it's me, Anna Sinfield, the host of The Girlfriends. I'm back with more one-off interviews with some truly kick-ass women on the Girlfriend's spotlight. I'm going to climb this. Is badness hereditary? Let's see how we can stop killing.

I'm not so intimidated. by her. What are you talking about? Listen to the Girlfriend Spotlight on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Welcome to Dirty Rush,

the truth about sorority life, the good, the bad, and the sisterhood. With your host, me, Gia Judice, Daisy Kent, and Jennifer Fessler. The reality of Greek life

has been a mystery for those outside the sorority circles until now. Is it really a supportive sisterhood that's simply misunderstood, or is there something more scandalous happening on campuses across the country? Let's get dirty. Listen to Dirty Rush on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hi, my name's Ali Phillips, and this is my story. I'm one of those genetically

unlucky people where my skin is very light, and I've always had a lot of moles. I inherited this from my mom, who also has a history of skin cancer. So I have been handicapped. having moles removed since I was a small child. I never thought anything about having moles removed. I just thought it was mainly for cosmetic reasons. I started laying in the tanning bed when I was a sophomore in high school because I wanted to be tan for prom. That was the popular thing to do back in the early 2000s when everyone wanted that bronze look. I remember reading all the waivers that you sign when you go to the tanning salon. And I remember thinking cancer from a tanning bed? That one happened to me. Never heard of it. So every spring then, I would lay in the tanning bed

a couple nights a week to prepare for prom. I really loved myself when I had a tan. I thought it made be beautiful. Then college came around and there was no more prom to prepare for, but I still wanted to be tan like all the other girls on campus. So I kept going to the tanning bed. Until one day in the spring of 2006 in my freshman year of college, I got a rash all over my body and I took a break from tanning because I figured that's what caused my rash. While I had this rash, I had accidentally scratched off a mole on my left thigh and it bled. I had always heard somewhere that if you scratched a mole and it bled or grew back, that it was a bad sign and it should be removed. So when that mole grew back over the summer, I had my mom scheduled me an appointment to have it removed.

that year by Christmas, Christmas break to be exact, that mole came back as a malignant melanoma. My mom gave me the news. I think she told me something like, oh, hey, just want to take another biopsy because that mole came back as a melanoma. You know, kind of no big deal. She was trying to downplay it a little because I was a little freaked out and I don't think she wanted me to freak out. You know, I was only 19 years old, so I didn't really know what a melanoma was. And I think my mom just really didn't want me to be scared. None of it really hit me until I was at the dermatologist's office being numbed up with a bunch of needles

and having a giant parallelogram shaped chunk removed from my left leg, then having them having to cauterize the wound and all that extra stuff. At some point during the procedure, I heard the doctor mentioned stage two malignant melanoma. And I thought, wait, what? I know what malignant means, and that sounds serious. It was incredibly painful once the numbing wore off. The swelling and the bandages I had to wear made it hard to wear normal jeans. I could barely walk anywhere because each step made me feel like my skin was going to break open. Mentally, it was a major adjustment because now I had a massive scar and I had to face the

fact that it happened to me. As a vain 19-year-old girl, that was a very important. a very big deal. So as the years went on, I continued my yearly skin checks with my dermatologist, and I became more responsible with my skin health and became less vain about my scar. I also found a whole new love for sunless hands. I was doing very well. I had one. Or so I thought. So 14 years later, I was busy planning a wedding for September when COVID-19 hit and everything was shut down, including my dermatologist's office. I had become really good at keeping an eye on my skin and determining what my need removed. So when I noticed a certain newer mole on my left thigh, I had to get it taken care of. It was large and had a smaller, darker mole formed on its border.

I was going to ask my doctor to remove it at my annual upcoming appointment, but that appointment was canceled due to COVID in the shutdown and my doctor not being able to have any in-office appointments. So I had to wait till July to have it removed when the office reopened. And sure enough, it came back as another malignant melanoma. I cried. A lot. I was scared.

Skin cancer is cancer. It was scary. What if it metastasizes? Every thought ran through my head at once. It had been 14 years since this happened the first time. I thought I was done. The dermatologist office was so far behind due to the prolonged closure that the soonest they could get me in for the surgery

was a month later on the 26th of August. I was completely devastated. I had been doing all the right things. Where did I go wrong? I didn't have time to pity myself. I had a full-time job as an occupational therapist and a manager of a rehab clinic and a wedding to plan. So I had the surgery and pushed through it,

and with the help of my wonderful husband and my family, I overcame it. In hindsight, I wish I would have known all the options of removal of procedures. I learned after the fact that there is another type of removal procedure that could have been less invasive and could have led me to having a smaller scar. I also wish I would have known the effect that just one sunburn has on your skin, how powerful and harmful tanning beds are, because I would have been more cautious even in my younger years. I now have two large scars on my left thigh, but I embrace this. because they're part of my story. And the process has made me a stronger, wiser, and more compassionate person. Thank you so, so much, Allie, for sharing your story with us. We really appreciate it. Yeah, thank you. Yeah, I can't imagine how it was stressful and scary that must have

been. Yeah, especially so young. Yeah. Hi, I'm Aaron Welsh. And I'm Aaron Olman Updike. And this is this podcast will kill you. And today we're talking about skin cancer. Yes. This is textbook quantity level of information. It's as usual, we've picked a topic that could easily be its whole own podcast series. It's one of our favorite things to do. But, you know, we're just going to cover all of it.

It's cool. Yeah, yeah. I mean, you'll definitely learn something from this episode. At least I hope one thing. I mean, I think probably many things. Okay. Fingers crossed. But before we learn anything, it's quarantine time.

It is, what are we drinking this week? We're drinking, here comes the sunburn. That wasn't a very good. That's pretty good. Was it? I do what you were doing. Maybe I like anticipated it. Yeah.

Yes, here comes the sunburn. is a delicious little drink that has sparkling pink lemonade and some vodka and some cherries. It's simple but delicious. Very delicious. We will post the full recipe for that quarantini as well as our non-alcoholic, Plessy Berita on our website, this podcast will kill you.com and on all of our social media channels. We certainly will. And on our website, this podcast will kill you.com, you can find all sorts of. of things ranging from links for merch and music by Bloodmobile, bookshop.org affiliate account,

goodreads list. You can also find transcripts and the sources for each and every one of our many, many, many episodes. And there's Patreon, there's a firsthand account form. It's, there's more. Wow. Check out. That's just what an amazing website, Aaron. Gosh. I know, right? Wow. Well, we've got a lot to cover, so maybe we should get started right after this break. Let's do it. Dinner shows up every night, whether you're prepared for it or not. And with Blue Apron, you won't need to panic order takeout again. Blue Apron meals are designed by chefs and arrive with pre-portioned ingredients,

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Order now at blueapron.com. Get 50% off your first two orders plus free shipping with code this podcast 50. Terms and conditions apply. Visit blue apron.com slash turrets. Terms for more information. Anyone who works long hours knows the routine. Wash, sanitize, repeat. By the end of the day, your hands feel like they've been through something.

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Ever feel like you're being chased by the marriage police? Welcome to boys and girls, the podcast where dating isn't dating. Arranged marriage is basically a reality show, except the contestants are strangers and your entire family is judging. You're sipping coffee with one maybe, grabbing dinner with another, and praying your karmic Ken or Barbie appears before your shelf life runs out. Trust me, I've been through this ancient and unshakable tradition. I jumped in, hoping to find love the right way, and instead I found chaos, cringe and comedy. And now, I'm looking for healing. Boys and Girls dives into every twist and turn of the arranged marriage carousel, the meat-awquard, the near-misses, the heartbreak, and let's not forget all the jokes.

Listen to boys and girls on the IHard Radio app, Apple Podcasts, or wherever you get your podcasts. So before we talk about skin cancer, let's talk about skin. Yeah. Yeah. I'm not going to go into too much detail. There's a lot of detail that we could get into about skin. I actually remember finding it very stressful to have to learn all of the different layers of skin like in med school. I don't know why, but it was a very stressful time. But we're just going to talk about the parts that are most relevant to learning about skin cancer.

There are three major cell types that are involved in our epidermis or our skin. Like I said, if you get into the nitty gritty, there's a lot more layers because the cells themselves change as they migrate upwards from our basal layer and eventually slough off, which is, what our skin does. But we don't have to focus on all of those individual layers. We can focus on two major classes of cells, the keratinocytes and the melanocytes. So keratinocytes are our skin cells. They include the basal cell layer, the bottom cell layer, that are kind of like stem cells of our skin, and then the squamous cells above that. And then there are the melanocytes. And milanocytes. And melanocytes are the cells that produce melanin, which is what gives skin its color. There's a lot of other cells in our skin.

They're all important. There's dendritic cells, which are like white blood cells that, you know, help protect against pathogens and invaders. There's longerhan cells. There's Merkel cells and other types of nerve cells. But we're going to focus on the keratinocytes and the melanocytes. And it's probably not too surprising to know that you can get. cancer in any and all of these types of cells. Skin cancers, like actually all cancers, are named after the type of cell that they originate from.

So there's three main types of skin cancer that we're going to focus on today, and they each have subtypes within them. And since you just learned the major skin cell types, it's not a surprise what types of skin cancer we have. There's melanoma, which is cancer. of our melanocytes. And then there's non-melanoma skin cancer or keratinocyte carcinomas. And that includes basal cell and squamous cell carcinomas. The end. Done. That's it. The biology section's over. I have some unanswered questions. Okay. I guess I'll try and go into a little bit more detail then. And again, because there are also other skin cells, There are other types of non-melanoma skin cancer.

That's a whole group of skin cancers that include the basal and squamous cells, but also things like cutaneous lymphomas, adenexyl tumors, Merkel cell carcinomas, which is all over the news right now because Jimmy Buffett just died from Merkel cell carcinoma. I was wondering. Okay. Yep. And other rare primary cutaneous or skin neoplasms or cancers. But for this episode, we're going to focus on the big three.

Basal cell, which is, spoiler alert, by far and away the most common form of skin cancer. Squamous cell, which is the next most common. And of course, melanoma, which is the most dangerous. Basal cell carcinoma is cancer that arises from the basal or bottom cell layer of the epidermis. And like I mentioned, this is actually kind of a plerone. pluripotent or like a stem cell layer at the base of our epidermis right before you get into dermis. And basal cell carcinomas, there's a number of different subtypes of them, but they often start out as a small, kind of pearly or almost like translucent, little papule or

little bump. It might be a bit red or irritated looking around the edges. There might be these little blood vessels called telangectasias. Some of them almost look like a taut blister kind of on the skin. Or it might just be a little spot that if you nick it or like scratch it, it just kind of bleeds and it never seems to heal quite right. Or sometimes they can grow quite large and have this like ulcerated center with these like raised edges kind of around it. What about size? Yeah, they can range massively. And the thing about basal cell carcinoma is that it is incredibly rare for this cancer to metastasize.

It's not impossible because any cancer can metastasize. And a metastasus means that a cancer has spread to a different part of the body from where it originated. It's very rare for basal cell carcinoma to do that. But it can be very locally invasive. which isn't that surprising if you think about it as a cancer of the very bottom layer of the epidermis. If it's just growing upwards and outwards from that epidermis, then it may not cause that much tissue destruction. But if it starts growing down towards the dermis, then it can cause quite a lot of tissue damage, especially because 80% of basal cell carcinomas are found on the head or neck.

There's a lot of places on our head and neck that don't have that much tissue to begin with. And so basal cell carcinomas are the kind that can, for example, cause a lot of damage to the nose or the ears or if they're near the eye. These can be incredibly damaging. My grandpa had on his nose, I remember he had a scoop taken out. Yep. My dad has had so many. Sorry, Dad, for calling you out. But so many basal cell carcinomas removed.

And we'll talk more about how much the technology has improved to be able to do these removals with minimal cosmetic damage, which is incredible. So it's interesting to me weirdly. It may be just because I don't know how the skin works. But you said that like the basal cells are formed this layer that's like almost stem cell like in nature. And yet it's still so mostly localized. I don't know why that just makes me think like, oh, and then it's. it's going to turn into a cell, a cancer cell of another kind and then migrate and then cause lots of problems. I mean, it's good that that doesn't happen, but I don't know. Yeah, it's interesting. One of the questions, this is spoilers for later, but one of the questions that I really was trying to wrap my head around and I still don't know the answer is why cancers metastasize. Like,

I understand how it happens and we'll talk about that, but why some cancers are more prone to metastasis than others. And I don't have an answer to that. I imagine that it's all dependent on the type of mutations that are found in that cancer, but I don't know what those are. And I wish that I did. So spoilers, I don't. Well, maybe someday we'll do like, I don't know, just a broad strokes cancer episode. I think it would be really fun to do that, honestly. I really do. It would be a mess of an episode, but it would be so fun. It's interesting. And then you know that at the very top of the episode, we would be like, why didn't we turn this into a mini-series?

Maybe we will. Maybe we will. Yeah. Anyways, going back to Faisal. Getting back to skin cancer. So the second type of skin cancer and the second most common type of skin cancer is a squamous cell carcinoma. And a squamous cell carcinoma is, again, from this uncontrolled proliferation of the squamous cells of our skin, that is all of the cells like above the basal layer essentially.

It's our skin cells, our keratinocytes. Squamous cell carcinoma often has actually precursor leaves. which are called actinic carotoses, or actinic keratosis is one of them. And these are little, often white, kind of flaky, dry, like scaly patches that can happen on the skin. And squamous cell carcinoma, similar to basal cell, can present in a lot of different ways and often might just look, again, like scabs or like a place that's just not healing right, but often isn't quite as pearly or translucent looking as a basal cell carcinoma. And the way that I think about that is that the basal cell is like a deeper cell layer,

kind of like poofing itself up, whereas squamous cell is more of these scaly type of keratinocytes that like make our skin our skin. And so it looks more like dry skin on top most often. Does that kind of make sense? Yeah. How is the turnover rate different for basal cells versus squamous cells? So your squamous cells, and I don't remember the exact time frame of like how long it takes for a cell to go from the bottom layer, like, and move all the way up to the top before we slough it off. It's a period of several weeks, I think.

But your basal cells can transform into your squamous cells. Like they're made from that basal cell layer. Okay, okay. Yeah. Why is basal cell carcinoma the most common or more common than squamous cell? I don't know, Erin. If there is a thing that I do not have an answer to, it's why this skin cancer and not that skin cancer. Yeah. It's just like, how does it happen?

I wonder if it has something to do with the fact that because basal cells are continually replicating? Do they already have certain mutations that make them more likely to escape that cell cycle checkpoints? That's what I was kind of trying to get at with the turnover question. Like, if squamous cells come from basal cells, then at what point do those mutations get introduced for it to turn into squamous cell carcinoma? I don't know. Oh, Aaron. I don't know. Okay. Food for thought. Foods and thoughts. So squamous cell carcinoma, like basal cell carcinoma, is far less likely to metastasize

than the next skin cancer that we'll talk about, melanoma. Melanoma is really kind of a different beast entirely. It is, quote, the bad one when it comes to skin cancers. melanoma is a cancer that arises from melanocytes. And melanocytes are these cells that are found in that same basal cell layer, that bottom layer of the epidermis. But melanocytes are the cells that make melanin. And melanin is a pigment that actually protects us against the major risk factor of all of these types of skin cancers, and that is UV radiation.

All of these types of skin cancers, the primary risk factor is sun exposure. And we'll talk in a minute about like how that happens. But what's interesting about melanomas is that these are cancers arising in these cells that are making this pigment that's protecting us against this radiation. And just like with basal and squamous cells, there are a lot of different types of melanomas. There's superficial or spreading melanomas, which tend to grow outward, like radially,

before they invade deep into the dermis. There's nodular melanomas, which tend to grow deep prior to, or at least more quickly than they grow outward. There's acral lentigenous melanoma, which presents not on sun-exposed skin, but on the palms or the soles of the feet or on the nail beds. There's also mucosal melanoma. There's a lot of different types. And many, but not all, melanoma, can arise from within a nevis, aka a mole. Mm. And moles, this is probably too much to get into, but there's also a lot of different kinds of moles. I am very curious. Please, please tell me more.

So there's there's junctional moles, there's congenital moles, acquired moles, compound moles, atypical moles. There's a lot of different types of nevi as like the official term for moles. Wait, but tell me what some of those things are. What is a junctional mole? So they all refer to different ways in which histologically the melanocytes and the melanin pigment themselves appear. So all moles exist because of melanin. Like there is melanin necessarily in a mole because that's what gives it its pigment or its color. But not every mole necessarily is a risk factor for melanoma. One main way that people might have heard of that's often used to help distinguish or differentiate benign nevo. from those that are dysplastic or more likely to either be a melanoma or be in the process of undergoing a transformation into a melanoma is what's called the ugly duckling sign.

Have you heard of that? Yeah. Yeah. Because while not all, and in fact not most nevi are risk factors for melanoma, having many of these melanocytic nevi or having a bunch of moles is a risk. factor for melanoma. So when trying to look at a person who has a whole bunch of moles and figure out which ones might be risky and which ones are no big deal, it's the ones that look off. The ones that look a little different from the rest are potentially of the most concern. And there's a few ways or a few characteristics that you like memorize in medical school to look out for. And they're easy to remember because it's A, B, B, C, B, C, D, E, F. Oh.

So, so it's A for asymmetry. So moles that have a symmetry to them are slightly more concerning than ones that are symmetric. Irregularity in borders. Mm-hmm. Color. And this doesn't necessarily just mean what color is it, but differences in color, especially like spots that are dark or light or A-pigmented all of a sudden, especially

a mole that used to be pigmented and now isn't. And then D used to be diameter, but it turns out that you can definitely have melanoma, even at very small diameters. So now D stands for dermatoscopic features. Okay. And a dermoscope is this really cool tool that uses polarized light and a magnifying glass to be able to look underneath the top layer of skin to be able to see features of moles and freckles and things that you can't see with the naked eye. That's cool. E stands for evolutionary changes or a mole or a spot that changes over time. And F is funny looking.

And I think that that kind of goes along with something that's changed, right? Something that didn't used to look like that and now it looks different. Yeah. Those are the types of features that people look for when trying to decide does a mole or does a spot need to be biopsied or removed. or is it not of concern? So those are the three main types of skin cancers. And like I already mentioned, the single biggest risk factor for all of these is sun exposure, UV light exposure specifically. There are, of course, huge differences in risk between individuals because of genetic or phenotypic factors, phenotypic factors driven by genetics. And,

And these tend to be markers of UV sensitivity. So these genetic or phenotypic factors are things like light skin, light eyes, light hair color, or like the, quote, inability to tan. And we'll talk a little more about that. And also the accumulation over time of benign sun-related skin changes. And those are things like I mentioned like actinic carotoses or solar lintiginies, which are just sort of large freckles that can appear over time because of the sun on your skin? I have lots and lots of those.

Oh, I am like essentially one giant freckle. Yeah. Same. Spotted with moles. Yeah. And what's really interesting is that especially for basal cell and in some ways for melanoma as well, there's data to suggest that it's not just. sun exposure, but it's intense sun exposure and especially intermittent periods of intense sun

exposure that might put people at higher risk rather than just low level sun exposure chronically, if that makes sense. So what would that look like intermittent levels of high sun exposure? In the literature, it's often described as holidays, right? Okay. So people who are not exposed every day to sun, but who maybe go on holiday somewhere where the solar radiation is much more powerful than a place where they live. And they're out in the sun all the time for a week or two and they get a big sunburn. And then they go back to not being exposed to the sun very often, etc. Yeah, yeah. Especially during childhood and adolescence. Okay. So I was wondering about, I have like, I'm so many questions.

that I don't even know where to begin or even how to articulate any of them. But what about age? Like, how does age come into it in terms of when you get your bad sunburns? Does it matter? I mean, you said adolescence and... Yeah. You can think of it as an additive effect. Let's go into, like, how this happens.

And then I think it'll make more sense why age plays a big role in it, shall we? So in essentially all cancers, and we've talked about this in several episodes now, like our hepatitis episodes, in our HPV episode, cancers are the result of a disruption in our normal cell cycle. Our cells replicate, right, and our skin cells happen to replicate quite a lot, but they do so in a very controlled way. They move through certain checkpoints, and these checkpoints are there to prevent damaged cells from multiplying. Cancers are the result of a disruption in this cycle.

When damage or mutations in our DNA allow for cells to grow unchecked in some way, to either live forever or to continue multiplying in an abnormal and an uncontrolled way, therefore spreading and causing damage. That is what all cancers are, and that is what they do. When it comes to skin cancer, UVA and UVB radiation, which comes from the sun, does a few different things to cause these types of disruptions. First, UVB radiation especially directly damages our DNA and our RNA. You can see our radiation episode for slightly more detail on that.

But essentially this radiation breaks the bonds in our DNA, and it leads to the formation of these dimers that aren't supposed to be there. And like substitutions, for example, of C for T or T for C. And these mutations can lead to a variety of different mutagenic products, depending on where they happen. UVA radiation also causes damage, but it does so a little bit more indirectly by increasing oxidative stressors and reactive oxygen species formation and just causing inflammation, like low-level inflammation in our skin kind of all the time. Now, in general, for the most part, our body is able to recognize, identify, and repair this DNA damage. And in the case of UV damage, it does so by literally excising these dimers, like being like, you don't belong here, and replacing them with the correct sequence. But over time, these mutations can accumulate as these repair mechanisms fail to excise and

replace every possible mutation or dimer that pops up. And if these mutations happen to occur in certain genes, including, for example, P-15, which is a tumor suppressor gene or a whole bunch of other genes, especially when it comes to skin cancer, then what you have is a disruption in this typical cell cycle. So now all of a sudden you don't have a checkpoint in place that should say, hey, this cell isn't right. Stop growing. Instead, you have unchecked, uncontrolled growth. And this is the process, again, by which all cancers happen. It just so happens that UV-Rexamins. radiation is the primary or at least the biggest source of initial DNA damage that leads to the mutations that lead to skin cancer. So the reason why skin cancer happens primarily in older

adults, so skin cancer is something that doesn't happen in children as often, is because these mutations occur over time. They have to be incorporated into the DNA. And, and And a lot of times it takes more than one mutation for a cancer to actually arise as a result. How deeply can UV radiation penetrate from like the sun? Oh, oh, oh, oh, oh, oh, oh. Such a fun question. So that question depends on your skin. Remember I said that melanocytes synthesize melanin. Mm-hmm.

So melanin's role is that. to help protect against UV light. So what happens when our skin is exposed to light is that our melanocytes synthesize melanin. Melanin is then transferred to the keratinocytes, to the upper layers of our skin. And what melanin does is it absorbs and dissipates that UV radiation. So variation in the amount of and the size of the melanocytes and the amount of melanin that they produce, as well as variation in the pigmentation and the tanning response that happens as a result of sun exposure plays a big role in the variations in both melanoma and all skin cancer susceptibility. So what's really interesting is that while, of course, every human is exposed to UV-radial,

right? Like all the time, every day. Maybe not every day, but at some point in our life. At some point in our lives. Obviously, not every human is going to develop skin cancer, even maybe people who are exposed to quite a lot of UV radiation. So not only is it going to depend on things like melanocytes and how much melanin, there are at least some specific genes that we know are related to increased risk of skin cancer, especially melanoc. And a lot of these have to do with melanin. There's a gene called MC1R or melanocortin 1 receptor and certain alleles of this particular gene that are associated with things like very fair skin, red hair, freckles.

These allelic variants essentially make it so that the melanin that is produced is a slightly different type of melanin that is not as protective or might mean that less melanin is produced overall. There are other mutations that can happen that can put people at even higher genetic wrist. Like there's a disorder called zero derma pigmentosum, which is a very rare disorder. But this causes an inactivating mutation in genes that are involved in that excision and repair process. So they can't come. cut out and repair that damaged DNA. So there's a lot of different potential sort of gene mutations that someone might have at

baseline that makes their individual cells more susceptible to another mutation induced by UV radiation. Mm-hmm. Tell me about the melanomas that happen on skin that is not typically exposed to the sun. Yeah. What about those? Yeah. It's fascinating. So a lot of these are acral melanomas. Those are the types of melanomas that can occur on your palms or your souls or even in the nail beds. There is some suggestion based on genetic studies of these melanomas that even though they're occurring on less sun exposed areas, they often still have UV signatures, meaning they have certain mutations that are very strongly associated with UV.

V exposure, which is fascinating. Huh. Yeah. How? That's honestly, that's the most that I have for that because you're right. Like all of these types of skin cancer can happen potentially on areas that are not exposed to the sun or at least not exposed to the sun very often. Yeah. That's all I got.

It's fascinating. Yeah. Do basal cell carcinoma or squamous cell carcinomas happen in places that don't receive? some? Yeah, they can. They can. Yeah. Wow. I know. Interesting. There's also suggestion, and maybe this plays more of a role in these cancers in areas that are less sun exposed, that another virus, very familiar to TPPWKY listeners, that is HPV, can also be associated with some skin cancers, especially some non-melanoma skin cancers, like squamous cell carcinoma. But we don't know very much at all about,

the specific subtypes or anything like that. Within these skin cancer types, if you get diagnosed once, you are more likely to develop another skin cancer. Now, does that apply across these types? Or is it just like if you get basal cell, then you're more likely to get another basal cell, or is it, you know, any of them? Yeah, it's a good question. In theory, you definitely could get any of them. And I don't have great numbers on, for example, if you have a melanoma, what's the likelihood that you may also have or get a squamous cell or a basal cell or, you know, any combination thereof? Part of that is because, as we'll talk about later, we don't have like tumor registries for basal cell and squamous cell carcinomas. So those are like not reportable data. But because they all

share common risk factors, certainly not uncommon to have multiple types of skin cancer. What makes melanoma so bad, so much deadlier? So melanoma is so dangerous because melanoma is the type of skin cancer that metastasizes. And the rate at which it metastasizes depends greatly on the depth. So the single most important factor when looking at like the risk of a melanoma, is how deep was it when you first saw it or found it and tried to cut it out. If a melanoma grows to greater than like four millimeters, which is like pretty thick, then it has pretty high rates of metastasis. And when it comes to metastasis, it is not often a good prognosis because we don't have

great treatment for metastatic melanoma. So that's really the reason that melanoma is the most kind of dangerous one and the one that by far is the most deadly when it comes to skin cancers. Now, why is it that melanoma metastasizes so easily? I still don't fully know. And that comes back to kind of what we were saying at the beginning. Like, why does one cancer metastasize so readily when another does not? Right. And again, my sense of it is just that it's the particular mutations that are happening in melanoma, or perhaps a characteristic of melanocytes themselves, that make them more likely to break off from the primary tumor, travel through the lymph system, and thereby cause metastatic disease. So you mentioned that there was not good treatment for metastasized melanomas.

What treatments are typically used for these different types of? of skin cancers? So most skin cancers, you can detect and then treat kind of at the same time with excisional biopsies or with excision itself. So depending on where the lesion is, if it's on the face or the trunk or the arms or the legs, you essentially just cut it out. And the key to cutting it out is making sure that you get the entirety of the cancer, that you have good margins, right? And depending on what type of cancer it is and how large it is, the recommended width of these margins will differ. When it comes to melanoma, especially as they get deeper, you have to take out quite a wide margin of tissue to make sure that you've really got all of the

potentially cancerous cells. But even for basal and squamous cell carcinoma, if you're not able to, you get all of the cancerous cells, then of course you're going to have a risk of recurrence, right? And that, of course, can be a problem if you have cancers, like I mentioned, on the face, right, where you don't have that much tissue that you're able to actually remove without having significant cosmetic or, like, structural damage. So there is a relatively new, I actually don't know when this was invented, technique called Mo's surgery. Have you heard of this? No. Mo's micrographic surgery. It's very, very cool. It's the surgical technique that allows you to take the thinnest possible margins around the entirety of a cancer because as you cut it out, as a surgeon

cuts it out, they slice it and then look at it underneath the microscope, the entirety of it to make sure that they got all of the cancer, if that makes sense. Yeah, yeah. So it's a way of doing it like in the moment rather than having to like cut out a chunk, send it to pathology, wait a couple weeks, come back, cut more, etc. Wow. And so is this like the same surgeon doing the cutting is the same person who is doing the identification of the margins and stuff? So I think a lot of times you have to have a second person there to identify, but it is

also the person doing the cutting who then also looks at it too. So you might have two people. Okay. And this is incredible, especially for places like the nose or the ears. But of course, it takes very skilled personnel. It's not necessarily available everywhere. But it's a really incredible technique that has been developed. And it's a really powerful tool.

It also has the lowest five-year recurrence rate for any treatment, especially for basal cell carcinoma. Wow. But it's also used very commonly for squamous cell carcinoma. That's really cool. When it comes to melanoma, you still do usually have to have pretty wide margins. And depending on how deep it is, you would then also have to do lymph node biopsies and screen for metastatic disease and then potentially do chemotherapy. And there are various chemotherapy agents that some of which target some of these specific mutations that we know are really common in melanoma.

But there just aren't as many as compared to a lot of other cancers that exist. Yeah. But that's skin cancer. My head is just full of information now. Well, that's good. So tell me, Erin. Yeah. I mean, how did we get here?

Yeah. It's a roundabout journey that we will take right after this break. I can't wait. Anyone who works long hours knows the routine. Wash, sanitize, repeat. By the end of the day, your hands feel like they've been through something. That's why O'Keefe's working. Working Hands hand cream is such a relief. It's a concentrated hand cream that is specifically designed to relieve

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Just visit O'Keef's company.com slash this podcast and code this podcast at checkout. like you're being chased by the marriage police. Welcome to boys and girls, the podcast where dating isn't dating. Arranged marriage is basically a reality show, except the contestants are strangers and your entire family is judging. You're sipping coffee with one maybe, grabbing dinner with another and praying your karmic ken or Barbie appears before your shelf life runs out. Trust me, I've been through this ancient and unshakable tradition.

I jumped in hoping to find love the right way and instead I found chaos, cringe and comedy and now I'm looking for healing. Boys and Girls dives into every twist and turn of the arranged marriage carousel. The meat awkward, the near misses, the heartbreak and let's not forget all the jokes. Listen to boys and girls on the I-heart radio app,

Apple Podcasts or wherever you get your podcasts. This season on Dear Chelsea with me, Chelsea Handler, we've got some incredible guests. Like Kumail Nanjiani. Let's start with your cat. How is she? She is not with a thing. Okay, great, great, great way to start.

So this is a great beginning and hopefully you'll be able to, I don't know, maybe you will cry. Amanda Seifred. Life is so short. If you feel something like that, you have that fire in you for this experience. It's not for a guy. It's for the experience of being in love and like it's bigger than a guy. Elizabeth Olson. I love swimming naked so much.

and I know you love taking pictures of yourself naked. I love to be naked. I just want to be in my brown underwear all the time. Ross Matthews. You know what kids always say to me? Are you a boy or girl? Oh my God. All the time.

I love it. I know. So I'm always like, hi. I try to butcher it up for kids, you know, so they're not confused. Yeah, but you're butching it up is basically like Doris Day. Right? No, I turn into Be Arthur. Listen to these episodes of Dear Chelsea on the IHeartRadio app, Apple Podcasts,

or wherever you get your podcasts. We humans have this weirdly fraught relationship with the sun. It's kind of like filled with contradictions. We've worshipped the sun since ancient times and built temples to honor the god of the sun. We've invented countless ways to mimic the effects of the sun, like tanning beds, as well as to block the effects that it has on us, like sunscreens and various sunclothing and sun hats. We've attached various meanings to how much sun you get, and we've created a whole host of myths about when or when not to use sun protection. We've battled skin cancers for centuries, and we've massively improved the outcome of those battles as our methods for detection

and treatment have evolved. We love and fear the sun, and for good reason. But despite this rich history, despite just how much we've learned about sun exposure over the centuries and then apply that knowledge to skin cancer prevention and treatment, the amount of miss and disinformation about the possible health effects of sun exposure, both good and bad, is staggering. Sifting through that information to find the good stuff is in and of itself challenging, but then there's actually applying it to your life, which, like most behavioral changes, is difficult. When we decided to do this episode, I honestly had no idea, like what area I wanted to focus on, which story to tell, because they're all really interesting, and they're all full of their

own rich, deep history. And so instead of just picking one, I kind of decided to do like a little bit of all of it, a little mashup of like how long we've recognized skin cancers and understood the link between skin cancer and sun exposure. Okay. Why tanning beds were invented and how they got so popular. Okay. The earliest sunscreens and a bit of myth debunking, not very much. I have papers to send you to instead of me doing all of that.

And finally, like a little bit of reflection on like where we stand or like why we don't do the things that public health tells us to do, including myself sometimes, right? Like, just, I don't know. Let's get started and see where we end up. Okay. I can't wait. And what better place to begin than with a couple of classics, Hippocrates and mummies. Love it. The word melanoma, which, by the way, is mostly what I'll be talking about in terms of the history of skin cancer, first shows up in the Hippocratic texts from the 5th century BCE. Melanoma, of course, comes from the Greek words for dark, melus, and tumor, Oma. So we know that melanoma was recognized at least that long ago, and we also have physical proof of it in the form of diffuse melanotic metastases found on the skeletons

of pre-Columbian mummies from about 2400 years ago in Peru. Yeah. And there are enough writings or mummies to give any indication of overall prevalence, but it seems pretty likely that these were not isolated cases or that it was like a particularly rare condition. But what I couldn't fully figure out was what physicians in ancient times thought caused melanoma or other types of skin cancers. Because the link between skin damage and even skin cancers and UV radiation wasn't established until centuries later, like the 19th century at the earliest. But this doesn't mean that sunscreens or other methods of sun protection

were only invented after that association was made. It's not like you need to know how mechanistically UV damages yourselves to know that spending long periods in the sun can lead to some pretty painful burns and that it's probably then in your best interest, to avoid that much sun exposure. Beginning at least in ancient Egypt, though probably dating even further back, people began to use plant extracts like rice bran, jasmine, and lupin,

to protect themselves from the effects of the sun. Ancient Greek athletes would often cover themselves, I read, in olive oil and sand when they were training for long periods of time outside. And I read that all of the oil. olive oil has an SPF reading of about eight, by the way. Okay. Which might be better than the baby oil that my mom used when she would tan. Yeah, yeah. And around 500 BCE, ancient Indian physicians wrote about zinc oxide as a sun protectant, as well as a salve for open wounds and burns, in the medical text, the Shakara Samhita. Sun protection wasn't limited to plant extracts

or mineral compounds, of course, various types of weaving, like how tight the weave was, was used to create clothing, veils, head coverings, and other types of clothing materials for added sun protection. And umbrellas have been around since ancient times in Egypt, Mesopotamia, China, and India, not just for rain, but to block the sun. I don't know why I love that idea. I never thought about umbrellas back then, but like, Duh. I love that. But these methods of minimizing the effects of the sun didn't come down just to avoiding getting sunburn. How much sun exposure you got, which was indicated by the tint of your skin, often took on a cultural meaning. And often that meaning was that the shade of your skin

relative to others, said something about your class, your occupation, your standing in society. Not everyone could afford an umbrella for sun protection, or even if they could, they probably couldn't afford the time spent holding it or paying someone to hold it for you if you're doing physical labor outside. Nor could everyone afford sun protective clothing or to replace torn or worn out clothing as frequently as other people. So historically, in many places, in many cultures, paler skin was held as an ideal within these societies since it was interpreted as you being wealthy enough to not spend your days laboring outside. And this is further illustrated by the many skin bleaching or whitening products going back

hundreds of years, many of which contain toxic metals like arsenic or mercury. And this is obviously very broad strokes, very in a nutshell, that I acknowledge lacks important nuance and doesn't represent all places at all times. But for many cultures, for large chunks of history, staying out of the sun was considered a luxury, at least until the early 20th century, at which point attitudes began to shift in some places dramatically. And to get at the drivers of this shift, the embrace of the tan, I'm going to talk specifically about the U.S. because perceptions of sun exposure were not consistent across the entire globe. As the 19th century came to a close, the negative sentiment towards

sun exposure was mostly still in full swing. For instance, take the pawns advertisements from the early 20th century that warned women to, quote, beware the kiss of the sun. The summer girl has no charm as great as the appeal of a complexion as clear, transparent, and like an apple blossom in its delicate soft coloring. Oh dear. Yeah, end quote. And of course, this isn't just about sun exposure and classism. There's obviously much more going on underneath the surface here in terms of general racism and the rise of the notion of white supremacy around this time and earlier and after. So keep that in mind, of course, but teasing apart how those were tied into this and the rise of the tan is just a bit beyond the scope of today.

But in terms of the sun specifically, though, it didn't just come down to sun exposure is bad because it means you're poor. People also had begun to attribute negative health effects to time spent in the sun. I'm not talking about UV damage and skin cancer. and the other things we now know are clear signs of sun damage. I'm talking about the idea that extreme sun exposure was thought to be the cause of many tropical diseases, which white people seemed especially susceptible to. Huh. Yeah.

In 1905, Dr. Chas Edward Woodruff published a book titled The Effects of Tropical Light on White Men, in which he detailed how the sun laid. to the deterioration of health and the development of, quote-unquote, tropical neurasthenia, which included vague symptoms like, quote, restlessness, irritability, fatigue, memory loss, insomnia, headaches, diarrhea, ulcers, heart palpitations, alcoholism, and insanity, end quote. Oh my goodness. Quite the range. And he went on to say that the U.S. was too sunny for the white people who lived there.

Quote, the American girl is a bundle of nerves. She is a victim of too much light. End quote. It's like, it's just, you know. Oh, my goodness. Mm-hmm. And another physician, Dr. Percy Brown, who was at Harvard, said that chronic exposure to the sun was the cause of, quote, unquote,

Americanitis. A condition characterized by, quote, irritability and extreme activity, end quote. I mean, I do feel like often irritable and extremely active at times about like, do I have Americanitis? Does that explain me? Or? Yeah.

I don't even know what that means. I don't either. I just really don't. Like it is, I think it might be meaningless is the answer. Oh my goodness. And this is all just about like white Europeans who came to the Americas. Like that's what they're talking about. Yeah.

Which is like the just the invaders. Yeah. Cool. Yeah. Okay. But attitudes towards the sun and sun exposure were about to do a complete 180. Okay. And warnings about too much sun or the health effects of.

Sun would disappear for decades. Sun began to be hailed as a healer of all. The quote-unquote sun cure developed in the early 1800s and refined in the 1870s when researchers found that exposure to UV-like killed bacteria and fungi, it grew tremendously in popularity. In 1882, Robert Koch, longtime friend of the pod, discovered that the tuberculosis Bacteria were killed when exposed to sunlight, which caused quite a bit of excitement because it suggested that maybe sun exposure could cure the disease. And that led to the invention of artificial

sunlamps by Niels Finson, which is the first time that humans were able to produce sunlight and less than 20 years after light bulbs were first invented. What? Isn't that cool? And it was to try and cure TV? Uh-huh. What? What? And, and it was to try and cure TV? And, and, the Finson lamp apparently did actually effectively treat the cutaneous form of tuberculosis. What? Yeah. And for this, Finson was awarded the Nobel Prize in 1904. What?

I love this. I know, I know. And so treatment for all forms of tuberculosis became centered around sunlight. This is in the pre-anibiotic era with the construction of countless sanitariums. particularly in areas with lots of sun and fresh air, such as the Adirondack Mountains in New York, where the first sanitarium in the U.S. was built. At that sanitarium,

a key part of this sun therapy was spending long chunks of the day reclining on specially designed chairs to soak up the sun. Atarondacks? Atterondack chairs. Oh, my God, stop it. Yeah. Isn't that good? Adirondack chairs were invented to cure TB by laying in the sun. Mm-hmm.

Ugh. Yep. That is one of my favorite, like, fun facts of the podcast. I think. I will never forget it. I will. But maybe not for me. I will until someone says the word Adirondact and I'll be like, did you know? Did you know? But the sterilizing and healing effects of sunlight weren't enough alone to drive this massive change in attitude. There had to be something more. And there was. Our old favorite, the Industrial Revolution. Always.

Always. With more and more people moving to cities and working in factories or in mines away from sunlight, a lack of sun exposure no longer meant that you were too wealthy to work. In other words, thanks to the Industrial Revolution, you couldn't tell how wealthy or which socioeconomic class someone was in based on their tan. This was unacceptable. The only way to not be mistaken for a poor person was to work on your tan, which wealthy white people began to do, spending time at beach houses or resorts for long weekends,

recreational swimming, golf, tennis, and bicycle riding became more popular, and sporty clothing for these activities tended to reveal more skin. And the pale skin that was once held as the pinnacle of refinement and beauty now carried with it a different meaning, that of the, quote, feeble, sunlight-starved, lower class, end quote. Huh. So-called diseases of dark. like rickets and tuberculosis rose in prevalence during the Industrial Revolution, as we've talked about on the podcast. And a common medical belief of the day was that, quote, pale, dull, and perverse children get so as a result of dark, gloomy schoolhouses and tenement rooms, end quote. This negative association with pale skin even found its way into fiction with villains like Dracula,

sporting extremely pale skin. The combination of pale equals poor and sun equals health created a powerful and lasting shift in the U.S.'s relationship with the sun. It's fascinating. Soon, sunlamps and UV bulbs found their way into homes and businesses, and physicians began exploring the potential uses of heliotherapy, which is from natural sunlight and phototherapy from artificial sunlight. sunlight. These bulbs were literally just exuding UV radiation all over the home.

Love that. Wow. Great. Great. Everywhere. Yeah. World War I demonstrated that sunlight did seem to help with the healing of compound fractures and ulcerated wounds. Tuberculosis and rickets soon found themselves surrounded by a whole host of other diseases that could allegedly be cured by UV light, like pneumonia, constipation, hypertension, hypotension, cirrhosis, arteriosclerosis, diabetes, and gastric ulcers. Not saying any of those can be cured by sunlight, but people tried to do it. I'm sure they did. Oh, yes. But sunlight was held not just as a curative therapy, but also a preventative one. Necessary to stave off colds and infections, help your metabolism, improve circulation, you name it.

parents were told to take their children outside for hours each day for their sunbath regimen. Listen to this quote from an article in the American Journal of Public Health from 1926. Quote, We have found that the best results are obtained by telling mothers that they must get their children sunburnt. The infant should be taken out on bright days for a time between the hours of 11, a.m. and 2 p.m. and the sun allowed to shine directly on its face. Oh my gosh.

Ah! Isn't that? I can't believe it. I can't believe it. I can. I can believe it. I... Ah!

Mm-hmm. In 1923, literary digest wrote that, quote, Nothing is better for babies or grown people either than a good coat of tan. have it on good scientific authority. Oh, do you? Do you indeed. Being tan was also the height of fashion. In 1929, Coco Chanel returned to the U.S. after a vacation in the French Riviera and declared, quote, the 1929 girl must be tanned. A golden tan is the index of chic. Wow. Yep. Of course, what remains unsaid in that quote is that it wasn't just the 1929 girl, but it was the 1929 white girl who must be tanned. Yeah. And I think that's such an interesting part of this whole history of

tanning. Yeah. I think, again, there's like whole entire podcasts that could be had about the the context of pale being beautiful versus tan being beautiful in the context of the U.S. and systemic racism and anti-blackness. Yes. But it's a very interesting part of the history of tanning as it relates to skin cancer especially. Mm-hmm. Yeah. It's complicated. Yeah.

There's a lot. There's a lot. It's like I said, there's a lot going on under the surface here that plays into this. Yeah. Yeah. But all this tanning was not without its obvious risks. Yeah. City health commissioners around the U.S. sent out warnings about too much tanning, and you could find sunburn clinics popping up all over beaches all over the U.S.

Oh, gosh. As a result, the first sunscreens began to be developed and commercially sold with the first U.S. sunscreen, copper-tone sun-tam cream, hitting shelves in 1944. And there had been other sunscreens before then, like Hammer's quinine mixture from the late 1800s. Una's chestnut extract concoction, who was the first, by the way, to suggest a link between sun exposure and skin cancer. Schuller, who founded L'Oreal's, his benzylacillate, and even dark red veterinary petrolatum, which the military had found to be the top contender when looking for sun protection methods. in case World War II soldiers got stranded on life rafts or in the desert.

Beyond the very apparent link between sun exposure and sunburn that drove the invention of these sunscreens, a more concerning finding came to light in 1928, which was the association between UV radiation and skin cancer, which was clearly demonstrated in a mouse study by Dr. G.M. Findlay. While it would take another almost 30 years for the link between sun exposure and melanoma to come to light, which pun absolutely intended, I wrote it in here. Come to light, I get it. Yeah, yeah. This finding between UV radiation and skin cancer was highly concerning, especially for the many public health departments or medical organizations that had previously endorsed Sun as this cure-all. and told parents to get their baby's full sun, sunburnt for two to three hours each day.

Aye, aye, aye, y, aye. Yeah. Like, only stop when there's sunburnt? Uh-uh. No. I just, it hurts to think about. I can't. I can't get over it.

JAMA, for instance, revised their position on sun exposure in 1936, saying, quote, as far as is known, man actually requires only a relatively, small amount of sunshine for the maintenance of normal health, and the greatest danger, perhaps, at the present time, lies in too much exposure to sunlight rather than too little, end quote. Like, whoops. By the 1930s, it was widely accepted in medical circles that sun exposure caused skin cancer. But for whatever reason, maybe the messaging was off, maybe the lure of the tan was just too great. Tanning and sun exposure only grew over the decades. The 1960s was a celebrate the beach decade with bikinis and beach movies and as destination travel grew more accessible,

a winter tan became a status symbol and a fabulous souvenir. Tanning guides popped up in countless magazines. Still today, they're in countless magazines. For instance, the rotissory method. You can find that. Yeah, it's just like, oh, to get full maximum sun exposure, rotate every 15 minutes or something. Okay. When to go out to seek the peak noonday sun and when to use things like baby oil or an aluminum reflector to enhance the power of the sun's rays. My mom did both of those.

Yeah. Yep. Yep. And if you wanted sunscreen, you were more likely to find sun tan, creams guaranteed to get you the tan you desire. Barbies with tan lines were sold, sun-loving Barbie in the 1970s, yep. In the 1980s, Baywatch came out, and so like tans basically continued to be the trendiest fashion accessory, and people overall just didn't seem to be concerned. Naturally, there were consequences. The public.

health campaign of the 1980s called Fry Now Pay Later, not great, was inspired by the rising rates of melanoma, which in the 1930s was thought to be a pretty rare skin cancer with a lifetime risk of one in 1,500 people. Wow. By 1980, that risk had shot up to 1 in 250 and just 5 years later was estimated to be one in 150 and still rising. And this is just in white people. Yes. Okay. And so I also don't know about detection methods too. Like how much of that is detection, awareness, not just of sun exposure, but like melanoma. Right, right. And other types of skin cancers. But I think you can't attribute that huge of a rise. Yeah. Yeah. Yeah, exactly. And, And while public awareness of the risks of sun exposure had at least increased, it didn't seem to have a big effect on the tanning industry, which was very much still in its glory days.

There was the tanning bed side of things. The first indoor tanning salon, tantrific, opened to the public in 1978 in Arkansas and was quickly franchised. 1970. Doesn't it seem like late? I also, I don't know why Arkansas is not the place I would have guessed. I don't know. I don't know. But I mean like 1970s, this was decades after the link between sun exposure. And skin cancer. UV radiation and skin cancer was found. Why? Yep. Well, within one year, there were 81 tantrifics. And by 2000, there were at least 50,000 tanning fern. facilities around the country. Wow. Yeah. Sun tan lotion and sunscreen represented the other major tanning industry, with companies advertising their products as a way to achieve a quote-unquote safe tan, which is a line that the tanning bed industry also used without a scientific basis for that

claim. And I do think it's fair to ask, okay, but how much did science know at that point? Quite a bit. Quite a bit. The effects of UVB radiation on the skin had been known about since the early 1800s or so, not necessarily as it related to skin cancer, but as it related to skin damage. And most of the sunscreens developed through the 1980s blocked or were supposed to block this type of radiation, UVB radiation. But they often let UVA radiation through. even though UVA radiation had been found in the 1960s to be linked to skin cancer and skin damage. Even into the 1990s, most sunscreens did not have UVA filters, just UVB. And that actually has played a role in one of these sunscreen myths that that sunscreen doesn't

actually protect from skin cancer. And part of that is backed up by like, oh, well, look at this paper and this paper and this paper. a lot of those studies were done when sunscreen only protected against UVB radiation. Got it. And so the UVA sunscreen was not widely available. Anyway. So these quote unquote safe tans advertised by tanning bed salons and sun tan manufacturers, what exactly then made them safe?

What's the safe part of this? Mostly by filtering out UVB radiation only. Some salons advertised their UVA-only lamps. Oh, dear. In other words, we're still blasting you with radiation, but it's just a different kind. And it's still not safe, but... Yep. Not safe.

Not a safe tan. And eventually, the FDA stepped in to regulate things like the contents of sunscreen and provide guidelines on application. which very few people follow correctly today, myself included, like how thick you apply it. And of course, tanning salons were required to display warnings and have customers sign a disclaimer. Did these regulations actually do anything to cancer rates? I don't know. From what I can tell, and I know, Erin, you'll tell us more about like current incidents of different types of skin cancers. it hasn't really seemed to.

Maybe there's a lag between cause and effect because these cancers can take years to develop, so we're still experiencing the consequences of that high-risk period. But I'm not sure it's just that. Because even if tanning beds have fallen out of style in 2023, sunscreen use among American adults

is still incredibly low. A paper for, from 2015 reported that only 14% of men and 30% of women regularly use sunscreen on their face and other exposed areas. And there are many cited reasons for this. One paper found that some of the most commonly reported reasons include cost, dislike of feel or appearance of sunscreen, and time constraints. Even when people are using sunscreen, a very small proportion of them are using it appropriately, reapplying often, using the right SPF, applying enough, rubbing it in, and so on. And I absolutely count myself among those improper users. In high school, I used to lay out

without sunscreen to try to get a tan for when school started. I don't really tan. So as a result, I got so many bad sunburns. Like my mom had to reschedule my senior pictures. because I was just red and peeling, red or peeling, like one of the two. That was my summer skin. I remember for one sunburn, I had to lay on the cold basement floor because my back hurt so bad. And I knew about sun damage and skin cancer then. And I know even more about it now. And while I'm better overall about putting on sunscreen before going outside, especially here in Denver where it's propelled. sexually sunny and higher altitude, I'm still not perfect by any means. Why? Like, why, not just me, but broadly speaking, where is this disconnect coming from and how do we overcome it? And I think if we knew the answer to that, we'd have lower rates of skin cancer and higher rates of sunscreen compliance.

But I think a big part of it probably comes down to having to make behavioral changes, a notoriously difficult thing, as well as the perpetuation of some pretty damaging myths surrounding sunscreens and skin cancers that have served in some ways to decrease overall confidence in sunscreens. Things like, I don't need sunscreen on a cloudy day. You definitely do. Or there is no practical difference between SPF 50 and SPF 100. There is, especially when applying a thinner layer.

than recommended. Or sunscreen use prevents me from making it of vitamin D. First, it's not clear that it does, and secondly, there are supplements. Or sunscreen is bad for you. And while it's true that there were studies showing that some sunscreens had ingredients that were absorbed by the body, in 2019, the FDA now requires sunscreen manufacturers to describe which ingredients are, quote, generally recognized as safe and effective, end quote, and ingredients that are not considered to be so are no longer included in any sunscreen sold in the U.S. And this is also a very active area of ongoing research. And that's just a small sampling of sunscreen myths with many more out there. And I'll post a great paper from 2020 titled Dispelling Myths About Sunscreen, where you can find a whole lot more.

But there is something. There is still this disconnect. And I think it would be really interesting. I didn't dive into the literature, but I think it would be really interesting to kind of read more into which approaches have been the most effective. You know, like is messaging surrounding sun exposure and anti-aging? Like, is that more effective than just skin cancer and sun exposure? Maybe. I don't know. Like we've come so far in so many ways when it comes to understanding our relationship with the sun in a biological sense. In testing for and identifying risk factors for melanoma and other skin cancers, we've come a long way in treating skin cancers in developing ways to protect ourselves from the sun, but we're still really far behind when it comes to actually using that protection. Shame is never going to be a helpful tool to get the job done. And I know that there can be a lot of shame or blame when it comes to skin cancer. And the battle of good information against bad information is perpetually ongoing. There's a big hill to climb. And so, Erin, I'll turn it over to you to tell us a bit more about that hill.

Oh, I will try to do my best. right after a short break. So when it comes to the epidemiology, it turns out that the incidence of skin cancers as a whole is pretty difficult to understand, to have numbers on, because like I mentioned, it's only melanoma that's reported to tumor registries, which makes sense in that melanoma

is the one predominantly that metastasizes that causes mortality, right? But there is no doubt, through all of the literature, that it is non-melanoma skin cancer, basal and squamous cell, that by far is the most common, and in fact might be the most common human cancers, period. Wow.

Okay. Basal cell carcinomas account for 70 to 80 percent, of all carcinomas, especially in the U.S., that's where a lot of this data comes from. And while squamous cell accounts for about 20 to 30%, and the total incidence of these two non-melanoma skin cancers in the U.S. is estimated to be over a million cases each year, and in the U.K. estimates are around 100,000 cases each year.

That's all I've got. Okay. For those. But what's important to know is that, and this is true of all types of skin cancer, a lot of the rates of incidents and prevalence are reported predominantly just in white people. In Caucasians. But all types of skin cancer happen in people of all skin colors. They just are more or less prevalent. in part because of the effect of melanin, right?

But what's important to know about basal cell, squamous cell, and especially melanoma, is that in people with darker skin, it often goes unnoticed these cancers, and so they have been found to be, in many cases, more aggressive or identified at later stages of progression and therefore have worse. outcomes. And that's a really important part of the skin cancer story as a whole. Yeah. Because it means that we're missing it. We're not seeing it because we don't think that it's happening in people in darker skin tones, which is not true. Right. When it comes to melanoma, which we have better data on, a 2018 paper estimated that worldwide, there's over 230,000 cases or 1.7% of all new primary malignant cancers that are attributable to melanoma. And that's specifically cutaneous melanoma, meaning skin melanoma, because you can also get

melanoma like inside of your body. It's like not only on your skin. What? Yeah, these melanocytes can just cruise around. And melanoma likely causes about 55,000 deaths each year, which is about 0.7% of all cancer deaths. Okay. That is global averages, and these incidents vary widely across the globe.

So in Southeast Asia, the estimates are like 0.2 per 100,000 person years as an incidence. In the Americas, the estimates are like 7 per 100,000, and Australia and New Zealand have by far the highest incidence. Some studies I read said 30 to 40 per 100,000 people, but some studies said as high as 60 cases per 100,000 people in Australia and New Zealand. And some studies reported much higher cases in Europe and the U.S., like 20 to 30 per 100,000. All of these types of skin cancer are on the rise. They are continuing to increase despite the fact that we have more and more technology

in the form of sunscreen and sunprotective clothing to actually prevent against the majority of these cancers. Now, I wanted to talk a little bit about sunscreen because I don't know if everyone knows how sunscreen actually works. Ooh, I'm so glad you're talking about this. There's two different major forms of sunscreen. There's physical sunscreens that provide a physical barrier, and there's chemical sunscreens.

All of sunscreens essentially blunds, block UV radiation so that they don't cause damage to our skin. So sunscreens prevent photo aging, and that's like a whole other podcast topic, as well as the actual DNA damage that puts people at risk of the development of skin cancer. Chemical sunscreens, which if you read the back of your sunscreen label, are things like oxybenzone or avobenzones, these compounds essentially absorb the high-intensity UV radiation UVA and UVB, and then convert that energy into lower energy wavelengths like infrared radiation or heat, which when I read that, I was like, is that why you get so sweaty

when you wear sunscreen or is that just me? I mean, I think if I'm like wearing sunscreen, I'm likely to be outside. Fair enough. In the summer. Although it's true that I do wear it in the winter here too because it's always sunny. It's always sunny in Denver. I love it. Physical sunscreens, these are things like zinc oxide, titanium dioxide.

They mostly reflect and refract the UV radiation, just like bounce it off your bod. Or there is also like micronized zinc oxide that can absorb the UV light and it behaves like a semiconductor and like shooge it away so that it doesn't cause damage. Yeah. That's the technical word? Uh-huh. That's the real. I love it. And so what is the actual evidence?

Because I think that it's important to kind of put this sunscreen in context. There is very good evidence that sunscreen protects against a lot of different forms of sun damage. It protects against forms of photo aging like wrinkles. It protects against telangetaceas, which is when you get little tiny blood vessels that form in response to this UV radiation. It protects against other pigmentary changes like solar lentigos and all of these things. And there's very good evidence in the prevention of squamous cell carcinoma with the use of sunscreen and some evidence for the prevention of melanoma, which like all of those is enough for me. The data is not as strong, interestingly, for basal cell carcinoma, the

prevention of basal cell carcinoma. It's unclear why. But something that I think is important when we look at the data, because there are a lot of studies that are not hard to find that, like, rail against sunscreen for some reason. Yeah. Like, there's no data for it, which just, like, is not true. Right. But this is difficult data to gather. So let's talk about the data that does exist. There is copious amounts of data to show that sunscreens of all of the various kinds prevent all of this sequelae of UV radiation exposure in human skin under laboratory conditions when you're using it exactly the way it's supposed to be used. There's also a ton of mouse model data that shows the slowing down of development

or the prevention entirely of things like melanoma in mice models of skin cancers. There is, as far as I could tell, only one randomized control trial that was done in Australia to actually, under real-world conditions, try and say, does the regular use of sunscreen prevent melanoma? And these are really hard studies to do. But in this study, people that were assigned to, quote, daily sunscreen use had significantly lower incidence of melanoma than those who were assigned to, quote, discretionary use. So like just use however you use sunscreen.

Mm-hmm. Melanomas, squamous cell carcinomas, and basal cell carcinomas, like most cancers, take a long time to develop. So to do a study to look at the prevention of a cancer like this by the use of sunscreen takes a very long time. And we know that sun exposure during childhood and adolescence is when you're at highest risk. So it's really difficult to be able to have studies that gather enough data to say that using sunscreen, like on a population level, prevents cancers. That doesn't mean that we don't have a ton of data to show that sunscreen and other sun protective methods do help reduce the risk of UV radiation, and UV radiation is the

major risk factor for all these skin cancers. I think it's really important and most, most, if not always overlooked in like popular media representations of science is data quality and what those data look like. And so if you come to the conclusion based on a study that's like, oh, we found, you know, pretty decent, moderate support that sunscreen use reduces the risk of developing squamous cell carcinoma. and you'd be like what moderate support, like that only it kind of does. But then considering just like you said, how difficult it is to get these data and how they are often not as, you know, certain data sets are beautiful. And some are just a little messier. Then that's just the nature of humans.

I mean, don't get us started on like nutritional epidemiology and remembering what you ate and so on 10 years ago. Give you started on that because it's my favorite thing to talk about. But yes, sunscreens protect against UV damage. And UV damage is the primary and really the only preventable risk factor for skin cancer. That's like period of the end. When it comes to like future directions of research, there's a few areas that I think are really interesting and that have a lot of promise. Of course, there's a lot of research to be done and being done on treatments for skin cancers, especially when it comes to melanoma and metastatic melanoma. That's a whole field of research in itself.

There's also really interesting research being done on AI and using AI to identify skin cancers or like deep learning computer stuff. Cool. All of this is fraught with, again, the knowledge that we are bad in general and we being the medical community and the scientific community at identifying skin lesions in skin of color. That's like across the board of problem. And it leads to, like I already mentioned, not identifying cancers as early in skin of color compared to white skin or light skin. But that, I think, is somewhere where if trained with the right data, AI could potentially be really beneficial in aiding clinicians in identifying skin cancers earlier. There's already some programs out there and some studies that have come out for things like breast cancer, like identifying breast cancers with computers compared to radiologists, which is really interesting. So it's not like this technology exists yet, but it's definitely a realm of future research.

research because skin lesions are things that you can take a photograph of. And if you can take a photograph of it, then you can give it into a computer and teach that computer how to identify things, which is just awesome. That's pretty cool. When you said AI, I thought you were going to say that we're trying to get it to write prompts like public health safety announcements, awareness campaigns for sunscreen and skin cancer. No, I've got nothing about that. Australia, apparently. had one of like the most comprehensive skin cancer prevention like national public health campaigns. Yeah. That was called slip, slop, slap, which I love that. Love that. I know. And then they had after that, this was like the early 1980s and then they had this whole Sun Smart campaign that really focused on like

adolescents and young people and trying to get them to wear sunscreen or sun protection and they went into schools and they did all these things. But I couldn't find a lot of data on like how. effective it's been because the rates of melanoma are still rising. Yeah, I do think it's really interesting to think about targeted campaigns and how different ones work for different people. Because I feel like one thing that we didn't really touch on at all is occupational exposure. Oh my gosh, yeah. For sun damage and skin cancers. It's, that's like one of the biggest areas. Yeah. Yeah. Oh, there's a lot. There's a lot, Erin. There's a lot. There's a lot. that could be done. There's a lot that could be better. We could all wear more sunscreen.

I mean, do you remember that that thing that was circulating in like 1999, wear sunscreen? No. What? What? Okay, I'm going to send it to you. It was like a spoken word essay that was played. I feel like had so many high school graduations in the late 90s, early 2000s. And it's like if I could offer you only one tip for the future, sunscreen would be it. Okay, I'm going to send this to you, and you have to listen to it. Okay, I love it. I feel like all I remember from high school graduations was like vitamin C. Oh, yeah.

I mean, this played right before that. Oh, I see. Okay. Yeah. Oh, well, sources? Sources. I got everything from that essay called Wear Sunscreen. I'm just kidding.

I have many. I'm going to shout out a few. One is a book called Shetting Light on Indoor Tanning by Heckman and Man. Then there was a paper from 2020 by Bennett and Kasha Moon called Dispelling Myths About Sunscreen, which I already mentioned. Then a paper from 2012 by Rebecca at all titled A Brief History of Melanoma from Mummies to Mutations. And then finally by Urbach from 2001, the historical aspects of sunscreens. I had a lot of sources for this episode, many of which have so much more detail about the specific, like, tumor suppressors and proto-oncogenes and all of the, like, very detailed detail about these different types of cancer. So if that is what you're looking for, ooh, I got you. There is a paper in the Lancet, just titled Melanoma from 2018. There's another one called Non-Melanoma Skin Cancer in the Lancet from 2010. And that was really great. I have specific ones on each type of skin cancer, basil cell, squamous cell. We've got more on the current status of sunscreen use and skin cancer and, oh my gosh, everything you could ever want.

On our website, this podcast will kill you.com under the episodes tab. You can find all of these and the sources from every other one of our episodes too. Thank you again so much, Allie, for being willing to share your story with us and with all of our listeners. we really, really appreciate it. Yeah, thank you. Thank you also to Bloodmobile for providing the music for this episode and every one of our episodes.

Thank you to our amazing audio mixers at Exactly Right. And thank you to Exactly Right. And thanks to you, listeners, for listening. This is a long episode, I think. I had fun with it, though. I did too. And a special shout-out, as always,

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