Short Wave - The Evolution Of Cancer Treatment

Episode Date: March 4, 2024

Recently, the US Food and Drug Administration approved a first-of-its-kind cancer therapy to treat aggresive forms of skin cancer. It has us thinking of the long history of cancer. One of the first recorded mentions of cancer appears in an ancient Egyptian text from around 3000 B.C. And although we now know much more about how cancer begins — as a series of mutations in someone's DNA — it's a disease people are still grappling with how to cure cancers today. This episode, cancer epidemiologist Mariana Stern talks about cancer history and treatment today — plus, why some people are more prone to certain cancers and why that might matter for curing them.Want to hear about advances in medicine? Email the show at [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hi, Shortwavers, Aaron Scott here. And today we're exploring a disease that is plagued humans since, well, the evolution of humans, cancer. Which cancer epidemiologist Mariana Stern says at its core is caused by mutations in our DNA. What typically happens is that one mutation happens and it stays there and then another one happens. and then those cells start to acquire certain characteristics that allow them to proliferate more than they should. And that's how we end up having a mass of cells,

which is what we call a tumor. And as long as the disease has been in recorded history, people have been trying to treat it. From the first description of cancer in an Egyptian text thousands of years ago, humans have tried using paste, salts, teas, and cauterization to care cancer, just to name a few. One milestone came in the 1700s when an English surgeon connected cancer

to a clear environmental cause. In this case, chimney sweeps, who developed cancer after being exposed to soot. The revelation led to a minimum age for chimney sweeps. And although avoiding the hazard might prevent cancer, if you got it, the options for actually treating cancer were pretty minimal.

Cancer was a death sentence. People would not be given a long time to live. Mariana is a professor in population in public health sciences at the University of Southern California. And she says that for a long time, cancer was often treated with surgery. So the idea was let's remove the cancer and that will take care of it. But then it was recognized that just removing the cancer often did not cure people because cancer cells were being left behind. Left behind to potentially grow back. Then around the turn of the 19th century, physicians discovered that radiation could treat cancer, but in some cases, it could also cause it. Chemotherapy

came several decades later in the mid-1900s. It gave doctors a way to kill cancer cells that surgery or radiation couldn't reach. The idea was that certain drugs targeted dividing cells. And since by definition, cancer is cells that don't stop dividing... If we give somebody this drug, all the cells are actively dividing are going to die. With all these advances in treatment, life expectancy for those. with cancer went up. Today, cancer survival is much higher than it was even a few decades ago. But that success is not across the board, because cancers don't affect everyone in the same way. And cancer treatments are not one-size-fits-all.

To address that, the new approach is evolving to a personalized approach. Today on the show, cancer, a single word for a complex sea of diseases. We take a look at all the ways the singular. idea of cancer is being unraveled by modern research, from the causes to why the disease hits populations differently, and how treatments are getting more and more personalized. You're listening to Shortwave, the science podcast from NPR. Okay, so Mariana, there are so many different types of cancer, lung cancer, brain cancer, different types of leukemia.

But for all that nuance, I understand that they can generally be boiled down to a handful of characteristics. Like, for one, they grow out of control by basically ignoring the signals that tell other cells to stop growing or to die. What are some of the other characteristics? Another important feature of cancer cells is that they have the ability to induce what is called angiogenesis, which means the creation of new blood vessels. So if you can imagine a cell, like the blood vessels being like a highway that, you know, with trucks bringing all the nutrients and the cancer cell is far away from the highway, they basically create new roads that go to the highways so that they can get nutrients much faster. And the final one is that they

have the ability to invade other tissues and migrate to other parts of the body where they sort of adapt to that environment and start growing there. People talk about finding a cure to cancer, but is it even something that can be cured or is it just something that we need to learn to treat? Yeah, so I think there are different elements in your question that deserve different answers. So one is that even though we conveniently group cancer as one disease, it's actually hundreds of diseases together. So I think the chances of finding one treatment or one way to cure what we call cancer, is impossible. And this idea that there are many cancers that is not just one disease makes me think about how there are also many things that can cause cancer. I mean, I know that a

small percentage of cancer is actually genetic, somewhere around like 5%. But for cancers that aren't genetic, can you talk about some of the things that cause them? So one is through the exposure to what we call carcinogens or cancer-causing agents. So we have learned that There are multiple environmental and even internal carcinogens that we're exposed to that can increase the amount of mutations that we accumulate. So some of the most common ones that we're exposed to is the sun, right? Sunburns, where your sunscreen. Exactly.

So we're sunscreen because sun causes mutations in our cells. Smoking, right, is one of the top ones that can cause cancer. other things that are known to cause mutations are alcohol, diets high in processed meats and red meats, being obese, being physically inactive. There are viruses that can cause mutations and other organisms like Helicopacter pylori is a bacteria that can cause stomach cancer. And it's very common in many Asian countries and Latin American countries. But I would like to mention that probably the most potent carcinogen that we have that we cannot do anything about yet is aging. So as we age, our cells deteriorate and accumulate more mutations. And that's why over time, if we look at the probability of getting cancer over a lifetime because we live so long nowadays,

pretty much one in two people are going to get cancer across their lifetime. One more reason to be afraid of getting old. Yeah, but I don't want the message to sound so gloomy because it's not like we're doomed, just because you get old, you will have cancer. I think a lot of it can be modified by paying attention to these other factors that we now cause cancer and are correlated with age because they accumulate over time. One big area of your research is studying differences in cancer rates and outcomes in Hispanic populations. And I know other researchers have also looked into other minority populations.

Can you talk about some of the things you all have found? Yes. So research among Hispanic communities here in the U.S. really lags compared to other communities, and that is a big disparity in itself. But there are some interesting findings. So in lung cancer, we see that among Hispanic patients, there are some unique mutations in those tumors that actually make them more likely to respond. to some therapies. So it gives them an advantage compared to other patients. We also have disparities

for other minority populations like American Indian, Alaska natives, African-American populations. They are not well represented in studies of cancer characterization. And this introduces a disparity because a lot of the drug therapies have been designed among patients of European background. And what we be learning is that tumors from minority patients, often they look different. They have a different landscape. So if we don't consider that, we may not be treating them with the best drug that those tumors are going to respond to. So this is what we call precision oncology. We are not delivering good precision oncology to our minority populations because of this lack of knowledge.

And we use this term Hispanic populations like it's a monolith, but it's not. It's a really diverse group of people. How do you define who's in this community? Yes, I think for a long time, Hispanic populations in the U.S. were studied as one large group. And it became very clear to many of us, myself included, that that was not going to really give us a good understanding of what was happening because of the big heterogeneity within these groups. So we have seen there are differences. So what we have learned is that Hispanic populations in the U.S. and across Latin America, they're really the resultant of the mixing of three different background populations.

The indigenous American populations who were throughout the American continent, who were admixed by the colonization of the Spanish and other European countries that came to the Americas. and then the African slave trade. And there are very interesting studies that show, for example, that Latina women who have more Native American ancestry, they have less chance of getting breast cancer than Latino women who have more European ancestry. And that's the interesting thing about capturing some of these genetic measures of ancestry,

that they not only capture genetics, they also are capturing other things that correlate with genetic. ancestry because, for example, if a Hispanic person has more indigenous American ancestry, that might be also telling us something about the communities that those people come from, the traditions that they have, the food that they eat. Right. And so to zoom out and kind of bring this back around to where we began, all of these differences make it even more pressing to lean into this idea of precision oncology and tailoring the approach for a specific cancer to a specific patient. Can you give us a sense of

treatment today and kind of what's on the horizon? Yes. So nowadays, for many cancers, it's no longer a death sentence, particularly if detected early, but cancer patients can live a long life and can live with cancer as a chronic disease, the same way that you can live with diabetes or heart disease. One of the ways in which the approach has changed over the past, decade or so is that not treating cancer based on the type of cancer, which has been the traditional way, but more and more the approach is changing to a more precision oncology approach, where the tumor is considered with its own characteristics and a cocktail of drugs or therapies will be designed to treat that particular tumor.

Yeah, and I've also heard of new treatments involving the immune system. Yes, so novel therapies are trying to leverage our own immune system so that we can attack cells by using, you know, immunological components, and this has proven to be extremely effective because our own immune system has a mechanism by which they can surveil our body, and when they see a cell that looks a little weird, they will kill that cell. So scientists have figured out clever ways to leverage, understand those mechanisms, and leverage them so that we can target cancer cells with immune molecules, which is called immunotherapy.

We know that cancer treatment is enormously expensive. It's not accessible to a lot of people. What sort of scientific innovations need to happen to make cancer treatment much more accessible to all people, given that we are all prone to these mutations and developing cancer. I don't think we need scientific innovations to make things work for everyone or to be accessible to everyone. I think we need innovations in how we provide health care to people in our country. So I think the main innovation that needs to happen is that there needs to be a commitment that every single cancer patient will get access to the best treatments that are

available to them. And that's not happening now. Mariana, it's been a pleasure talking with you. Thank you for sharing your time with us. Thank you, Ion. Before we head out, I want to do a quick thank you to all of our Shortwave Plus listeners. We are eternally grateful to you. Your support makes this show possible. If you're a regular listener and you've not yet subscribed, we'd love for you to join.

You'll get the show without sponsor interruptions. You can find out more at plus.mpr.org slash shortwave. This episode was produced by Burley McCoy and edited by our showrunner Rebecca Ramirez. Britt Hansen checked the facts. Gilly Moon was the audio engineer. I'm Aaron Scott. Thanks for listening to Shortwave from NPR.