The Peter Attia Drive - #170 - AMA #25: Navigating the complexities and nuances of cancer screening

Episode Date: July 26, 2021

In this “Ask Me Anything” (AMA) episode, Peter and Bob dive deep into cancer screening, including why it’s important, what you need to know about a test, and Peter’s approach with patients. They specifically discuss various screening methods, explain important terms like sensitivity and specificity, and how layering and stacking different tests in tandem can improve predictive values. They conclude with a discussion on one of the more exciting screening tools, diffusion-weighted MRI, and how it’s changing the cancer screening landscape. If you’re not a subscriber and listening on a podcast player, you’ll only be able to hear a preview of the AMA. If you’re a subscriber, you can now listen to this full episode on your private RSS feed or on our website at the AMA #25 show notes page. If you are not a subscriber, you can learn more about the subscriber benefits here. We discuss: The importance of cancer screening [1:15]; Cancer screening terms: sensitivity, specificity, false positives, and false negatives [8:25]; Cancer screening terms: positive and negative predictive value [17:00]; Improving predictive value by layering tests, and the predictive values of mammograms [25:45]; How smoking impacts the predictive value of cancer screening [30:45]; Liquid biopsies for ruling out cancer and the blind spots of common cancer screening tests [33:00]; The difference between cancer originating from inside versus outside the body [41:15]; How diffusion-weighted MRI is changing cancer screening [45:15]; Summary of Peter’s approach to cancer screening [53:45]; and More. Learn more: https://peterattiamd.com/ Show notes page for this episode: https://peterattiamd.com/ama25  Subscribe to receive exclusive subscriber-only content: https://peterattiamd.com/subscribe/ Sign up to receive Peter's email newsletter: https://peterattiamd.com/newsletter/ Connect with Peter on Facebook | Twitter | Instagram.  

Hey everyone, welcome to a sneak peek, ask me anything, or AMA episode of the Drive Podcast. I'm your host, Peter Atia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created, or you can learn more now by going to peteratia MD dot com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode. Welcome to this week's episode of the drive. Today is an AMA with Bob Kaplan. And in this episode,

we go super deep on cancer screen. And we've had so many questions about this, and we kind of lump them all into one episode. So we get into kind of the what you need to understand, cancer screenings, sensitivity, specificity, positive negative predictive value, all those things, and then kind of go through the different modalities, i.e. how you would actually go about doing these screens, and how you can improve their predictive value by stacking them on top of each other. So hopefully you enjoy this one and check it out. This is probably a really good one to check out on video because we use a lot of visuals including a spreadsheet that you can manipulate to better understand the concepts. So if you're a subscriber and you want to watch the full video of those podcasts

remember you'll want to see it on the show notes page and if you're not subscriber and you want to watch the full video of those podcasts, remember you'll want to see it on the show notes page, and if you're not a subscriber, you can at least watch the first part of this video on our YouTube page. So without further delay, please enjoy AMA number 25. Hey Bob, that's a lot of books behind you, man. Have you read all of them or most of them? Thanks for noticing, Peter. I'm a voracious reader. Sometimes my appetite is too big.

I have to admit, I haven't read all of them. Maybe 90%. I think at this point. It's impressive. Everything, the classics, literature, science. Mostly the classics, you can probably tell by the book binding on some of those. Yeah, hard to get them out of the shelf, to be honest,

to pull those things out. They're in there so tight. Yeah, hard to get them out of the shelf, to be honest, to pull those things out. They're in there so tight. Yeah. And it's good, too. Your kids can do little projects, flattening leaves and stuff like that. Yes. We've got more of those going on. This is fun for the whole family.

All right. Well, what do we have on the docket today for AMA number 20 something 25? 25. 25. In a similar vein as some of the previous AMAs, I consolidated a bunch of questions around a particular topic, and this one is cancer screening. We've gotten a bunch of different questions related to cancer and cancer screening, so you've got maybe a flavor of some of the questions that we've received.

How do you think about cancer screening? Why and or when should I be screened? Which tests are worth getting? What do you think of liquid biopsies? How do you interpret sensitivity and specificity of tests? What are those actually mean? What are some screening tools for cancer you use in your practice? It was another one. I don't know if this was a question from someone,

but I found this very interesting. And this question is, can you discuss how you categorize cancers and how you screen for each? So I remember you told me this too, and it was pretty interesting. I this question is, can you discuss how you categorize cancers and how you screen for each? So I remember you told me this too, and it was pretty interesting. I don't know if everybody would suspect this answer, but cancers outside the body versus cancers inside the body. So we'll get into that a little bit,

but I think it probably makes sense to start off with sort of in general. I know you're a strategy person. I know you'll have tactics too. Now, just to be clear, Bob, do we have three or four hours set aside for this podcast? Hopefully it's the latter. Yeah, I think this could be a long one.

Where would you like to begin? I think we should begin from the top. The first question was, how do you think about cancer screening? I guess putting this in the context of what we're interested in clinically probably sounds repetitive, but longevity has these two components, and they're not independent, but sometimes it's helpful to think about them in isolation. Lifespan, health span, how do you live longer,

and then how do you live better? In many ways, cancer versus the other major chronic diseases that rob a person of lifespan, namely the atherosclerotic diseases, and the diseases of dementia and neurocognitive decline. The latter two tend to go more hand in hand with the reduction in health span. In other words, by definition, when a person has Alzheimer's disease, their quality of

life by either cognition is also deteriorating, so they're experiencing both the slide in quality of life and eventually length of life. And similarly, in people that have advanced atherosclerosis, while of course it's true that people die suddenly of heart attacks who are otherwise totally healthy, a lot of times the reduction in the ability to carry out activities of daily living kind of moves more hand in hand with that. I would say that's a little less the case with cancer. Obviously cancer is still a disease whose primary risk factor is age. So age is the greatest risk factor for cancer just as it is for the other two diseases. But it's also in some ways a little

bit easier to think of cancer in isolation from the health span stuff that decline in physical and mental and emotional state. So if you're trying to imagine a world in which you can live longer, as we've discussed many times previously, that means living in a world where we delay the onset of chronic disease and or have better tools to live longer with chronic disease.

But you know that I much favor the former option because we've basically spend most of the history of modern medicine working on the latter option with very, very limited success. Let's now pause it for a moment that one of the pillars of longevity is minimizing mortality from cancer. So where does screening fit into this?

Well screening is one of three pieces that you would envision, right? The first piece would be how do you prevent cancer? The second thing would be how do you screen for cancer and detect it early? And I'll explain why I think that's necessary. And the third is how do you treat it when you have it? We can talk a lot about the former,

how do you prevent cancer? We've had many podcasts and we have many podcasts coming up where we're going to get into the treatments of cancer. But I want to focus this one on the prevention piece. So why do I believe that? Well, this is a controversial topic. I want to say first, so not all people believe that screening matters. But I think the simplest explanation for why screening matters is the evidence that suggests that a cancer that is caught earlier is easier to treat than a cancer that is caught later. In other words, if you catch a breast cancer or a colon cancer when there are tens of millions

or hundreds of millions of cancer cells, Your odds of treating that successfully are better than if you catch the same cancer years later when there are billions of cells. And the evidence for that basically comes from examining how patients respond to the exact same drugs in the adjuvant setting versus in the metastatic setting. What does that mean? So the adjuvant setting versus in the metastatic setting. What does that mean? So the adjuvant setting is when a drug is given to a patient

who has no visible cancer. So these are patients that may have had the visible cancer removed. You believe that they have microscopic disease that remains and you give them a drug like herceptin for a hertunous positive breast cancer. And if you compare the outcomes of those patients to the outcomes of patients who were given the exact same drug

for the exact same phenotype and genotype of the cancer, but in the metastatic setting, there's no comparison in the outcomes. And one explanation for that may be that the more mature cancers, the ones that have been around longer have developed more mutations, they are more difficult to treat. So it is therefore my belief that the more we can do to screen

for cancer and catch it earlier, the better we will be. But we do pay a price for that. We pay a financial price for that. In other words, it costs money to screen early. And we pay potentially an emotional price from that because as we'll get to, and you alluded to, we have to now get into false positives and false negatives. But at a high level, Bob, that's how I think about this topic around cancer screening. Yeah, it's telling to, if you look at statistics on five-year survival. So what are the odds of you surviving a cancer? And then if you look at specific cancers like breast cancer, you're talking about you catch it early and it's a local cancer. It hasn't metastasized and the statistics on that is the five-year survival rates are 99% and then you

go to a like a distant cancer, so a metastatic breast cancer, and it's closer to about 25% in terms of the five-year survival. Also, what you alluded to as well, the false positives, false negatives, I said I alluded to that. So that gets into sensitivity, specificity, and I didn't mention this, but positive predictive value, negative predictive value. And I think it probably would be helpful to go into that. And I think pictures are probably worth a thousand words in this, in terms of looking at how good a screening tool is and determining that stuff, sensitivity, specificity, et cetera.

We want to just start explaining those things. Sure. We've got some slides that we use with our patients, so go ahead and pull these up and we'll walk through that because I think if you want to take ownership over your own understanding of cancer screening, you'll definitely want to get to a point where you're really fast-out with these terms. Thank you for listening to today's Sneak Peak AMA episode of the Drive. If you're interested in hearing the complete version of this AMA, you'll want to become a member.

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