Science Friday - Why Cancer Death Rates Have Decreased Over The Last 30 Years

Episode Date: August 5, 2024

“Cancer” is a dreaded word in the doctor’s office. But about 40% of us will be diagnosed with cancer at some point during our lives, the most common being breast, prostate, and lung cancer, according to the National Institutes of Health.But in the last few decades, major progress has been made in the world of cancer treatment and prevention. Cancer death rates have decreased by about 30% over the last quarter century, with some of the largest decreases seen in lung, melanoma, and myeloma cancers. The Biden administration’s Cancer Moonshot program aims to reduce the number of cancer deaths by at least 50% by 2050.Early detection methods like mammograms and colonoscopies have improved outcomes for many types of cancer, and new treatment options, like cancer vaccines, immunotherapy, and targeted genetic therapies, have shown promising early results. And the breakthroughs made from the development of the mRNA covid vaccines are bringing even more promise for hard-to-treat cancers.Dr. Siddhartha Mukherjee, assistant professor of medicine at Columbia University and author of the Pulitzer Prize-winning book The Emperor of all Maladies: The Biography of Cancer, joins guest host John Dankosky to give a broad update on the progress made in cancer treatment and prevention. They also discuss the role AI can play in new breakthroughs, and why some cancers are still particularly difficult to treat.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Why have cancer deaths decreased so much over the last few decades? That's a 25 to 30 percent decrease in mortality from cancer over the last 25 to 30 years. That's a big number. That's a big leap. It's Monday, August 5th, and you're listening to Science Friday. I'm Cyfry producer D. Peter Schmidt. There's a word that you never want to hear in the doctor's office. It's cancer. About 40% of us, though, will be diagnosed with cancer at some point during our lives.

That's according to the National Institutes of Health. But just in the last few decades, major progress has been made in the world of cancer treatment and prevention. And the breakthroughs made from the development of the mRNA COVID vaccines are bringing even more promise for hard to treat cancers. Here's guest host John Dankoski with a broad update about the progress that cancer researchers have been making and what's on the horizon. Dr. Siddhartha Mukherjee is an assistant professor of medicine at Columbia University. He's also the author of the Pulitzer Prize winning book, The Emperor of All Malady, the biography of cancer. Dr. Mokkerjee, welcome back to Science Friday. So good to have you. My pleasure. Thank you for

having me. So I'm sure that you get this question a lot, but to kick off our conversation, why exactly are cancers so hard to treat compared to other diseases? Well, cancers are, as you just pointed out, is a word in the plural. There's not one cancer, but many cancer. Many cancers. In fact, even if you look within one subtype of breast cancer, you'll find many, many, many sub-types of breast cancer. And each one demands a different kind of treatment because they're genetically different. Cancer is not one disease, but many diseases. And in each case, we're trying to figure out what the commonalities and what the differences are. And that's made it a very different problem than, for instance, you know, another disease like diabetes, where,

for the most part, it's a problem with insulin and insulin signaling. And that's where you have the central conundrum, which is that it's not one disease, but many diseases. And each disease has its own solution and its own problem. When exactly did we start to realize just how complicated a problem this is, that you have all of these different types of diseases that behave in different ways? Well, there was an inkling quite early on when physiologists in the 1940s and 50s began to realize that the same therapy applied to the same cancer could lead to different, very, very different results. Take childhood acute leukemia. By the 1960s, 60% to 70% of children were being cured

using intensive chemotherapy, but 30 to 40% were not being cured. So there was a question already, you know, what was different about those children? The cells look the same, as far as we can tell under the microscope, but there's something different. And then since the 1970s, 80s, and 90s, when cancer genetics became more and more predominant and understood, it became quite obvious that the genetics of cancers, even within a particular subtype, let's say leukemia, are very different from each other. And so I think it was a gradual dawning of the idea that there's not one, but there are many kinds of cancer even within a particular subtype. I think many of us grew up with the idea that we had a few major types of cancer treatments.

There's surgery, there's radiation, and there's chemotherapy. Talk, if you would, about some of the new approaches that have come on the scene in just the last couple of decades. Well, so let's begin with the most important ones, which is cancer prevention. You have to think about cancer as a disease that can be prevented, detected, and treated. And it's a pyramid. The pyramid, the bottom of the pyramid is prevention. The middle of the pyramid is detection. The trouble pyramid is treatment. In cancer prevention, we've had a small revolution of sorts in understanding the role of inflammation and a very particular kind of inflammation. People often say, you know,

what does inflammation mean? Inflammation means many different things to have different people. But a particular kind of inflammation seems to be able to incite cancer cells to grow. And so, you know, a lot of effort is being put into figuring out what that inflammation is, how to prevent it, what causes it. For instance, we now know that air pollution of all things is a strong inflammatory signal for the growth of particular kinds of cancer. We now know that most likely agents that we knew as potently cancer causes,

causing carcinogenic, such asbestos, may have a very inflammatory component. So identifying that inflammation has become a very important part of cancer prevention. The second piece is early detection. These trials are still in progress. I'm optimistic about them, but they're still in progress. Can we detect cancer early in its earliest phases. Some of them have been phenomenally successful, colonoscopy. Great example.

Mammography, less obvious an example, but also has had impact. Papp smearing. And of course, you know, again, in the prevention realm, cancer vaccines, such as vaccines against human papillomavirus, which causes cervical cancer. Finally, treatment. Treatment, it gets a lot of attention. In treatment, we have the first use of rational or targeted immunotherapy, the use of the body's own immune system to go and kill cancer cells within the body.

And to that, if you add new forms of therapy, such as targeted therapy, again, that disabled particular genetic mutations that goad the cancer cells to divide. We have a whole new range of cancer treatments. So again, to summarize, a lot more going on in prevention with the identification of new states such as inflammatory states that guide or goad cancer cells to divide and grow and understanding of how to prevent that. In early detection, new vaccines and the possibility of detecting cancer early to the out early, still in the middle of trials, still undergoing evaluation. And in cancer treatment,

new targeted therapies, and most importantly, immunological therapy against cancer. I guess I'm wondering if these three pillars here, the prevention, the detection, the treatment that you've talked about, if you view these as all equally important toward these declining numbers that we're seeing, because we have seen cancer death rates go down in general, is there one of these three that has been. more important in your mind than the others? Almost certainly prevention has been important. Virtually every disease that we know about in medicine has been most impacted by prevention. Cardiovascular disease, great example, you know, changes in diet lifestyle,

changes in, you know, blood pressure management, changes in management of cholesterol, etc. Are all preventative measures. They prevent heart attacks before they happen. And that's been the driver of the decline in cardiac death. And so by the same logic, almost certainly prevention has been the major driver in the decline in cancer-related deaths from various kinds of cancer, including most importantly lung cancer, prevention of smoking, other cancers, cervical cancer, the vaccine against human papillomavirus. And, you know, changes in diet, lifestyle, and others caused a decrease in cancer deaths by preventing cancer from coming. up overall. How big has this drop in?

How to summarize, lung cancer and cancers related to smoking, massive decrease over the years. Other cancers, pancreatic cancer, much less so. But overall, I would say that the numbers released annually by the various institutions, including the National Institute of Health, I've shown about a 1% to 2% decrease in mortality every year, which would sound small, but over 25-odd years, that's a 25 to 30 percent decrease in mortality from cancer over the last 25 to 30 years. That's a big number. That's a big leap. Speaking of big leaps, as I mentioned in the introduction, the Biden administration has a goal of reducing the death rate by at least 50 percent over the next 25 years. Is that an achievable goal in your mind? If we keep on that 2 percent

trajectory, which we can by doing more research, by funding more research, by undisputed, by undisputable, standing of prevention in particular, but also treatment. I think that a 2% decrease per year is a reasonable goal and a 2% decrease every year will actually cause a 50% decrease over 25 odd years. So I don't think it's unreasonable. It just means that the momentum has to be kept up. It's not an unreasonable goal. People say, oh, you know, it's a pipe dream. It's not. We've been seeing a 2% 1% to 2% decrease every year across cancers. Some would need more attention than others. I gave you some examples. Gliblastoma, brain cancer, pancreatic cancers, and others need more attention. But overall, I think that a to 1 to 2% decrease every year is a reasonable goal and has been

achieved over the last few years. Because there's such a disparity in the types of cancers and how we're able to treat them and prevent them, I guess I'm wondering if you can give us an example of a type of cancer that didn't have a lot of treatment options available. But nowadays, if you were diagnosed, it really wouldn't be as big a deal. It would be something that you could probably tackle in some way. There are several examples. I'll give you a couple. The most striking one is a kind of leukemia called chronic myelogynist leukemia CML. It used to really be a death sentence 30-odd years ago. Very bad treatment and transplant. It is highly manageable. Most patients now take a single pill and they're basically on that pill for life. And as far as everything is concerned, their cancer is

in a protracted remission. In the middle ground would be a cancer like multiple myeloma. Multiple myeloma is a cancer of blood cells. It lives in the bone marrow. Rapid advances over many years have caused that cancer year after year to have a greater and greater response rate to these medicines. So much so that we can now see that over the last 10 odd years, there's been an incredible improvement in the treatment of multi-old.

It's still an incurable cancer, but it's a chronic disease. Many patients have lived 10 years, 15 years, 20 years with multiple myeloma. On the far end of the spectrum, you know, of course you have metastatic pancreatic cancer, metastatic gallbladder cancer and other forms of cancer where we haven't seen much of improvement in the last decade or so. And those remain real mysteries and frontiers in cancer therapy. You've mentioned this and the mysteries involved. What can you tell us, and let's just take pancreatic cancer, for instance, what can you tell us

about why there's such a mystery. What is it that's so particularly difficult or troubling in terms of how we treat pancreatic cancer? Well, there's several reasons and there's several unknown reasons. You know, there's known unknowns and unknown unknowns. So let's talk about the known unknowns. The known unknowns are pancreatic cancer has a set of mutations, genetic changes that drive the cancer that don't seem to have very good drugs against them. So we can't sort of generally apply good drugs against pancreatic cancer. In the unknown, unknown category, for some reason, these tumors, pancreatic tumors, are not very responsive to the immune system. So there's a huge spectrum even within pancreatic cancer. Why that they don't respond to immunotherapy we don't know?

It's unlike, for instance, melanoma, which responds very well to immunotherapy. It's unlike, for instance, childhood leukemia's which respond very well to chemotherapy. It's a unique, unique. And in some cases we know the answer and in some cases we don't. We've been talking a lot about death rates from cancer, but it's a bit of a different story for cancer incidence rates, which are actually going up. What can you tell us about that? It's very difficult. Your audience needs to understand that cancer incidence rates are very important to distinguish from death rates. Cancer incidence rates can rise in real terms and can rise in false terms. In real terms, by that I mean, really something is going up because of some reason that we don't understand or we do understand. In false ways,

cancer incidents can seem to rise because we are detecting cancer better. So just to give you an example, if we were to deploy a test, that was to detect cancer early. A great example is in South Korea many years ago. They started, you know, giving ultrasound machines to patients, to doctors' offices. And the incidence, the incidence of thyroid cancer went up dramatically. But the death rate from thyroid cancer didn't go up at all. So that means that we were detecting much, much more because you can put a machine and next to someone's neck and say, oh, you know, you have thyroid cancer. But those cancers are never likely to kill you.

Those cancers are not a problem. So incidents is something we need to be very careful about. They're truly, in some cases, incidences of cancers that are rising. And that's real. But in other cases, there are incidences that are rising that are spurious. So I always say when people say, oh, you know, the incidence of X cancer is increasing, I always say, well, was there a new test? Was there a new way of detecting these cancers that suddenly became available?

And don't be fooled by that because that is just a false, that is just a spurious result. That said, there are some incidences that are truly rising. Colorectal cancer, colon cancer and rectal cancer in young men and women, we don't know why, is rising. Esophageal cancer, cancer of the esophagus in young men and women was rising because of alcohol and cigarette smoking. So there are some true spurious ones and there are some true real ones. We need to distinguish between them, but don't get fooled by the idea that just because an incident rises means that there's more cancer around. It may mean that we're more detecting more of it, but it's actually just been the same.

Before we run out of time, I want to talk a bit more about cancer vaccines, which we've talked about on the show before. Can you tell us a bit about what promise you see in this particular therapy? Cancer vaccines are early in their development. Cancer vaccines are an idea that you could create a personalized immunological way by which the immune system could be incited to attack your particular cancer. And in an early study in pancreatic cancer, with a lot of work, a number of companies have shown that you can create a personalized cancer vaccine. These studies are very early. I would warn people against sort of over interpreting them. They have not been subjected to what would be called the gold standard, a phase three study. There's a lot of promise, but there's a lot to be done before we can make a conclusion about whether these cancer vaccines are real, but they have real benefit and whether they can be really scaled to patients across the board in various forms of cancer.

What is something that is on the near-term horizon you think in cancer treatment that you think will help us get to that big leap? I mean, what are you really excited about right now, said Arthur? I'm excited about ideas that are completely new in cancer therapy. So, you know, can we exploit the metabolism of cancer cells? Cancer cells digest and metabolize nutrients differently from normal cells. Is that a way that we can exploit them such that we can choke off the cancer cells metabolism? I don't know. That would be interesting. AI is very interesting because AI can produce new medicines against cancer that didn't exist before, couldn't exist before. And so we're looking at a number of

AI efforts to understand what's wrong with the cancer cell and can we make new medicines against it. And finally, of course, you know, the enrollment of clinical trials, particularly in prevention trials, we try to see how we can prevent cancer and enroll patients in trials for the early prevention and early detection of cancer, I think are really interesting. Do you feel overall positive about where we are right now in terms of cancer research? I mean, when people get a diagnosis of cancer right now, it's a much different thing than if they'd gotten a diagnosis 20 or 30 years ago. Are you feeling particularly positive about where we are right now in terms of our research

efforts and what you think is coming up next? Look, this is a killer disease. It depends on the kind of cancer. There's a lot of work being done on various kinds of cancer, lots of frontiers, being pushed, lots, everything moving in simultaneously. Do I feel optimistic? Yes, I feel optimistic as long as we sustain the effort, this one to two percent decrease. If we stop the effort, I feel pessimistic. So my optimism is dependent on a, whoever the new administration is, rededicating its life and effort in that direction and increasing the funding for research and development of new cancer

therapies. If that's the case, I feel optimistic. And we'll see if that's the case or not. Dr. Saddam Mukherjee is assistant professor of medicine at Columbia University. Thank you, as always, for speaking with us and lending your expertise. I really appreciate it. My pleasure. Thank you very much. And that's it for today. Lots of folks help make the show happen, including Jordan Smudjik, Charles Bergquist. George Harper. Full of some airs. Next time, we'll preview a satellite under construction by the European Space Agency that aims to search 200,000, stars for signs of planets and measure the age of those stars.

I'm SciFri producer Dee Petersmith. See you then.