Dr. Rhonda Patrick: What is the single best lifestyle shift that someone can do right now to positively, you know, affect their lifetime cancer risk?

Dr. Kerry Courneya: So every year in the US, about 2 million Americans are diagnosed with cancer, and the American Cancer Society estimates that about 40% of those cancers could be prevented if everybody followed sort of the optimal lifestyle, suggestions that they make. So we could reduce those 2 million diagnoses every year to about 1.2 million. So they're not all preventable, but we could certainly prevent a bunch of them. So number one on the list, I'm sure everyone will know, is smoking.

That's the biggest risk factor for cancer, and it's the one that many of the public health people have focused on for many years, reducing cancer rates, making great gains in cancer reductions, in cancer rates because of reductions in smoking. Assuming you're not smoking, which is 80% to 85% of the American population, obesity is actually the second on the list of risk factors for developing cancer. Unfortunately, obesity is going in the other direction. As smoking rates go down, obesity rates are going up. So we're starting to see more obesity-related cancers. Assuming you're not smoking and you're not obese, next on the list is actually alcohol consumption.

You might have heard of the Surgeon General's warning recently about the link between alcohol and cancer that many people are not aware of. So there's a lot of alcohol-related cancers as well. After those sort of big 3 lifestyle changes, yes, exercise and diet are important. And exercise has been shown to reduce the risk of, you know, maybe 8 to 10 of those cancers. There's over 100 different types of cancer. So it's a very complicated disease, all different cancer types. But we now have evidence suggesting that exercise will lower the risk of getting some of those cancers, particularly colon cancer, breast cancer, endometrial cancer, and several other cancers as well, such as stomach cancer, esophageal cancer, and a few others.

So yes, some evidence that these lifestyle changes really can reduce your risk of getting cancer.

Dr. Rhonda Patrick: If someone had limited time and resources in the sort of 80/20 sense, so if you were going to put in 20% of your effort to kind of get 80% of the reward. Do you think that, you know, what are some of the prevention strategies that would give you the biggest bang for your buck, like cancer screenings, exercise, things like that?

Dr. Kerry Courneya: So for sure, if you're a smoker, that's absolutely the best thing you can do is quit smoking, and you can really substantially reduce your risk by quitting smoking, and it has fairly quick benefits in terms of lowering cancer rates. If you're obese, then yes, going on a weight loss program and reducing obesity would be the biggest thing.

If you're a heavy drinker, then that's going to be a key thing. Assuming you're none of the above, you're not particularly overweight or smoking or drinking heavily, then I think exercise really is next on the list. And, you know, the general recommendation is the public health guidelines of about 150 minutes per week of moderate-to-vigorous-intensity aerobic exercise. Some evidence has suggested muscular strength training can lower the risk of some of these cancers as well, but most of the recommendations are really around sort of, um, moderate-to-vigorous-intensity physical activity. I know, I know, um, the major area of focus of your research is looking at how exercise affects cancer treatment, but I, I, there are some interesting questions I have with prevention as well.

Dr. Rhonda Patrick: You're mentioning obesity being a big risk factor for, for a, a variety of different obesity-related cancers, and perhaps there's people that have genetic predispositions. Maybe they have, you know, some of these BRCA1, BRCA2 variants that may increase the risk of breast cancer, for example. Is there any evidence or do you have any opinions on whether someone that may have those risk factors, if they're, if they incorporate, you know, exercise into their personal routine, is that something that can help negate some of that cancer risk, even if they still have the genetic predisposition or even are obese, for example?

Dr. Kerry Courneya: Yeah, there is good evidence on that. So one of the mechanisms how exercise might lower the risk is through managing obesity.

But what we also see is exercise lowers the risk of cancer regardless of your obesity status. So we can do the subgroup analysis of those who are BMI above 30, overweight, category healthy weight, all of them show a reduction. So obesity is not the only mechanism by which exercise is lowering the risk. So even if you're obese and you don't lose weight, exercise can help you lower the risk of developing cancer. We even see this with smokers. So we can break them into sort of the smokers and the non-smokers with lung cancer risk, and even those who are smoking, exercise will help them lower the risk.

Of course, that's small compared to the impact of not smoking, but it shows that exercise works within these groups to lower their risk, whatever is kind of driving your risk, whether it's obesity, whether it's smoking, you can benefit from it. The genetic stuff, we haven't seen quite as much evidence yet. You know, the BRCA genes you talked about there, it's like an 80% chance of getting breast cancer and very high with ovarian and some of these other ones. So you're almost on a kind of genetic trajectory that would be very hard to stop, you know, with a lifestyle change. So I haven't seen as much evidence there suggesting that it can be beneficial for those patients. There's other options for those patients in trying to reduce their risk.

Dr. Rhonda Patrick: Yeah, that was probably the most extreme genetic predisposition case. I mean, there's other genetic predispositions as well, or maybe a family history, if someone's got like a family history.

Dr. Kerry Courneya: And we've seen some of the studies look at that, trying to look at kind of, and just do it as you say, by family history, a very simple way of looking at it. And we do find that exercise lowers the risk of developing some of these cancers, even in those who have a family history.

Dr. Rhonda Patrick: There's, it seems like it's really just a panacea. I mean, in some regards, obviously, you know, if you're a smoker, you don't want the take-home message to be, I'm gonna exercise but still smoke, right? Like, no, like you should, you should quit smoking, right? That's like the number one thing.

But, but the fact of the matter is, and, and we'll, I'd love to get into some of these mechanisms in a minute about how exercise is, you know, how it's playing a role in cancer prevention and, you know, affecting tumor biology through metabolic signals. I mean, glucose regulation being a big one, right? I mean, even if you're someone who is obese and you're exercising and you're increasing glucose uptake into your muscle, I mean, that's very beneficial to not have it then available for a lot of cancer cells, you know, which, you know, primarily do use glucose for fuel. So, what about someone who is, let's say, not obese, they're healthy, maybe they're in their 40s, and they're someone that's more like a weekend warrior, maybe. I don't even know if that would be the term.

Maybe they're someone that just goes for a jog on the weekends only. Would there, would there be a case to make for those people to maybe push a little bit higher intensity than just going for your, your jog on the weekends in terms of like making an impact on their cancer prevention?

Dr. Kerry Courneya: Yeah. So what we see in the cancer prevention literature is there is a dose-response association, as we say. So that means the more exercise you do, the greater the risk reduction. So even though we can kind of look at different cut points and say, here's kind of an amount of exercise that will give you a benefit, we know that more is better. And there's various ways of getting that more.

One of it, as you've pointed out, is increasing the intensity, but also increasing the frequency or increasing the duration. And what you see with the exercise guidelines nowadays, they've almost backed off any recommendations in terms of the frequency-duration component. It doesn't really matter how you slice dice that exercise. So this guideline of 150 minutes per week, we used to say 5 days per week for 30 minutes. And then we used to say, okay, well, spread it out over at least 3 days and in minimum durations of 10 minutes. And now they're not even saying to spread it out over multiple days, and they're not even saying it needs to be a minimum of 10 minutes at once.

So the whole weekend warrior thing brought— well, you can probably go on a Saturday and Sunday and do 50 minutes, you know, if you're out doing hiking or some other activity, and that might be just as beneficial as spreading it out over different days. Now, that's on the prevention side of things. Things get trickier, I think, on treatment side of things where maybe more frequent bouts are important because you're looking at the acute effects of exercise accumulating acute effects. But in terms of the general prevention strategy, the— The more you do, the better. And it doesn't really matter how you slice it up over the course of a week, as long as you get to that 150 minutes.

Dr. Rhonda Patrick: Is there a limit on that?

So we're saying 150 minutes of moderate-intensity exercise, you know, depending on where you, what journal you read for the definition of moderate-intensity exercise, you'll find it's, you know, your heart rate max is going to like, what, 70%, 75% of maximum heart rate. So, I mean, you're, you're getting some sweat on your brow there. If you were to do, let's say, 300 minutes a week, you were to double that of moderate intensity, or you were gonna also increase the intensity, right? So you're doing more vigorous types of exercise, you're going above that 70, 75%, you're going to 80% of maximum heart rate. Would you continue to see decreases in cancer risk in that? I mean, is there, is there a limit? Like, does it—

Dr. Kerry Courneya: Yeah, it's a good, it's a good question.

So the general recommendation is actually 150 to 300 minutes. So, you know, 150, we kind of use the minimum to getting these benefits, and then those benefits will continue to accrue up to about 300 minutes, and then the curves kind of plateau after that. You know, you can certainly do more than that, but in terms of bang for your buck and really getting the benefits is getting up to that 150 minutes and then further increases as you get to 300 minutes, but it does kind of plateau after that.

Dr. Rhonda Patrick: Okay, so really, it's better to be on the higher end of the recommendations, whether that's, you know, the moderate-intensity exercise, 300 minutes a week, or vigorous-intensity exercise, the higher end being, what, 150 minutes?

Dr. Kerry Courneya: That's right.

Dr. Rhonda Patrick: Okay, yeah.

Dr. Kerry Courneya: so it is viewed more as the minimum of achieving that, and all these guidelines note that further benefits can be gained by doing more. So we set that guideline around 150, and additionally, getting up to 300 can be more. And generally, the guidelines just sort of double weight vigorous minutes. So when we say it can be 150 minutes of moderate or 75 minutes of vigorous, you kind of get double credit for the vigorous intensity exercise or any combination of the two. It doesn't have to be all moderate or all vigorous. You can mix it up as well. But that's roughly the extra benefit of the vigorous is this kind of double weighting that you're probably getting about twice the benefit as you might get with moderate intensity exercise.