Live Long and Well with Dr. Bobby

#52: We can reduce our cancer risk

• Dr. Bobby Dubois • Season 1 • Episode 52

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Cancer is the second leading cause of death, and while it sparks fear for good reason, 40% of cases are preventable. In this episode, I outline six practical, evidence-based steps that can help reduce your risk.

We begin by understanding which cancers are most common based on gender—breast, colon, and lung in women; prostate, colon, and lung in men. While some rare cancers (like pancreatic or ovarian) evoke greater fear, the focus here is on the ones we’re more likely to face and can meaningfully act on.

Next, I break down risk factors into two categories. Some are unavoidable—your sex, age, or family history. For example, if a close relative had breast or colon cancer, early screening or genetic testing may be warranted. However, only about 5–10% of cancers are directly linked to inherited genetic mutations (American Cancer Society
).

The more empowering list? Avoidable risk factors—where our actions matter most. Smoking remains the leading modifiable cause of cancer, responsible for about 19% of all cases. Excess weight and obesity account for another 8% and are especially tied to hard-to-treat cancers like pancreatic and ovarian (ScienceDirect
) and PubMed
). Visceral fat appears more predictive than BMI alone. Alcohol, especially in large quantities, is also linked to liver, GI, and breast cancers.

Some risks are cancer-specific. HPV causes nearly all cervical cancers, and melanoma is largely driven by UV exposure. Air pollution, especially particulate matter, may slightly increase lung cancer risk (ASCO Global Oncology
).

Step three is to act on what you can. Quit smoking, aim for a healthy weight, wear sun protection, and ensure your kids get their routine HPV and Hepatitis B vaccines
. Exercise plays a major role too—high activity levels correlate with 10–20% lower risk of several major cancers (JAMA
). In colon cancer survivors, regular exercise reduced recurrence by 30% (PubMed
).

Step four is awareness: don’t ignore new symptoms like unexplained bleeding or lumps. Early detection can be life-saving.

Step five is screening. If you're 45 or older, colonoscopy is now recommended. Women should get regular mammograms and PAP smears, and individuals with smoking history may benefit from lung CT scans. For rarer cancers with family history, targeted screenings may apply. I also address why whole-body MRIs
 and liquid biopsies
 aren’t ready for routine use.

Step six? Don’t put your hope in supplements. Large trials show omega-3s, vitamin D, beta carotene, and vitamin C offer no real protective benefit (NEJM VITAL Study
, Meta-analysis on Vitamin C
, JNCI on aspirin
).

Takeaways:
You can reduce your cancer risk by modifying lifestyle factors like smoking, weight, and activity. Don’t delay screenings—they catch cancers early when treatment is most effective. And remember: no supplement replaces proven preventive strategies.

Visit drbobbylivelongandwell.com
 for more evidence-based tools, and listen to the full episode for actionable steps to help you live long and well.

SPEAKER_00:

Cancer is probably the most feared diagnosis that your doctor could tell you. And it's common. It's the number two cause of death. Are there evidence-based ways to lower that risk? The answer is definitely yes. Listen for six practical steps that may save you from this tragedy. Hi, I'm Dr. Bobby Du Bois, and welcome to Live Long and Well, a podcast where we will talk about what you can do to live as long as possible and with as much energy and figure that you wish. Together we will explore what practical and evidence-supported steps you can take. Come join me on this very important journey, and I hope that you feel empowered along the way. I'm a physician, Iron Man triathlete, and have published several hundred scientific studies. I'm honored to be your guide. Now, this is the fourth in the series of Can You Reduce Your Risk? We did heart disease, cognitive decline, and stroke. And here is the fourth. If there are other categories or diseases you'd like to understand about lowering risk, send it my way. Love to get feedback and suggestions. About one in three people in the United States will develop cancer during their lifetime. And hearing that word brings fear and tears to most of us. We all have loved ones or ourselves that have received the diagnosis of cancer. You may have also heard that there's a rising number of colon cancer cases, even and especially in people under the age of 50. Before diving in, I wanted to share that I've tried to create a safe space for you with this podcast, where I'm not selling anything. There's no ads, there's no subscriptions, there's no companies I own. There's no hidden agenda, just evidence-based insights. I hope you can trust. Look, I at times I may be wrong, but I'm certainly not being driven by any profit motive. I just wanted you to know that. On to our cancer story. It's a good news, bad news story, as like many of the topics we discuss here on this podcast. 40% of cancer cases are preventable. And it's been estimated we've lowered the number of cancer deaths over the last 50 years by 5 million. Now, 80% of that is better prevention and better screening. 20% of that is our treatments have gotten better. That's the good news. Now the bad news is 60% are not preventable. But that doesn't mean we should give up thought and hope. If we can find those cancers early, we will be much better off. So I've put together a six-step framework, six steps you can take to reduce your cancer risk, all built around evidence. And I hope you'll listen carefully and I hope you will take them to heart and try them. Okay, step one, determine which cancers are more common or most commonly might affect you. And then, of course, we're going to focus on ways to prevent those. So the most common cancers differ between men and women. For women, it's breast cancer, colon cancer, and lung cancer. Now, uterine cancer, ovarian cancer, very worrisome, but somewhat less common. Men, it's prostate cancer, colon cancer, and once again, lung cancer. Now, we all think lung cancer due to smoking, and that's true for most cases. But 10 to 20% of lung cancer cases are in non-smokers. So we do need to think about those as well. Now you may be thinking, well, what about skin cancer? That's very common. Well, if we get rid of the non-malignant ones and focus on uh like melanoma, then it's not that common overall, but we will talk about ways to prevent that as well. Obviously, there are cancers that we fear that aren't in that top list, like pancreatic cancer or ovarian cancer, because it's really hard to treat them, and so we fear them. Of course, there's leukemias and myelomas and brain cancer and kidney cancer. But right now we're going to try to focus on the most common ones and the ones where we think, I think you can have the best impact. Now, even if uh cancers do crop up, basically we want to get to that cancer as early as possible, and that is one of the steps. All right, step two, define your risk factors for cancer. Now, some of those are going to be unavoidable. So if you're a woman, you're at increased risk for breast cancer. If you're a man, you're going to have an increased risk of prostate cancer. And as you get older, cancers are more commonly going to happen. So those are what I call the an unavoidable set of factors. There's also your family history. Do you have a family history of breast cancer that happened in a mom or a sister or an aunt? If so, you might want to undergo some genetic counseling and testing, like the BRCA gene that you might want to know about. If colon cancer runs in your family at young ages, you might need earlier screening. But let's also keep in mind that only 5 to 10% of all cancers are known to be strongly linked to a gene defect, a mutation that came from a parent. Cancers in general do have mutations, but I'm talking about the ones that come from your parents that are truly inherited. That's a pretty small number. So obviously, you want to be aware of it and do what you can, but it's not, for most people, it will not impact their risk of cancer. Okay, now we get to the all-important avoidable risk factors. These are risk factors that we can do something about. The number one risk factor for preventable cancer is smoking. It still is smoking, even though fewer people in the United States smoke. It's been estimated that about a 19% of all cancer cases are due to smoking. Here's another one. We understand being overweight as it affects our heart, it affects our brain, but it is truly a risk factor for cancer. And it isn't just for people who are obese, you know, a BMI above 30. People who are overweight, which is typically referred to as BMI of 25 to 30, they are also at risk for cancer and an increased risk at that. We haven't really talked too much about sort of general fat and visceral fat, the fat that's around your organs and in your muscles and such. That fat is at an increased risk for cancer, more so than just cosmetic fat. And I may do a podcast episode if you want on visceral fat. How do you measure it? What does it mean? What can we do about it? Well, also, alcohol is a modifiable risk factor for cancer. Now, for cancers like liver cancer or GI cancer, generally the amount of alcohol that people have been drinking is a fair bit. But I did talk in my episode on alcohol that there can be a slight increase in cancer, even for fairly small amounts of alcohol intake. So listen to that episode if it's of interest. So those are general causes that are modifiable. But there's also some cancer-specific things that are also preventable. So most cervical cancers in women are due to HPV virus infection, human papilloma virus, almost 100%. So if you can stop the infection from happening, your risk of cervical cancer may fall close to zero. Melanoma, the skin cancer, the malignant thing that we all fear, that's pretty much driven by UV radiation. Obviously, there are some cases unrelated, but generally it's felt to be due to sun exposure. And lung cancer. Lung cancer, of course, smoking is a critical one, but there's also some data about air pollution. Air pollution in a meta-analysis of 61 studies, now these were observational studies, they found that tiny particulate matter in air pollution may increase your risk of lung cancer. And you know, if you're sitting in a city that has pop pollution, I'll come in just a few minutes on maybe what you want to consider. It's not clear if air pollution uh increases your risk of other cancers, but it does seem to affect that uh lung cancer. Colon cancer, there's data that suggests that your diet is influential. People talk about fiber. I talked in my bacon episode number 41 about processed meats. In that episode, I netted out to if there's any increase, it's a tiny, tiny increase. So if you enjoy your bacon like I do, I still eat my bacon. Okay, so now we have figured out which cancers we might focus on. We figured out what our risk factors are, some avoidable, some not. Now we're going to get to part three, step three. Avoid what you can. Get rid of the risk factors, reduce the risk factors if you can. Smoking, obviously. If you are able to cut back on smoking, please do so. Visit your doctor, find out all the different ways they might support you in that. If you don't smoke, wonderful. All right, obesity, even being overweight. Look, it's hard, it's hard to deal with weight issues. I've talked about it multiple times, but if there's another reason to think carefully about losing the weight, maybe uh trying an Ozempic or a Monjar or one of those, avoidance of cancer might be a key one. And being overweight or obese is related to some of the cancers that are really hard to avoid and treat, like pancreas and ovary. So, yes, being obese or overweight affects lots of cancers, but particularly those two, which are quite worrisome. All right, try to reduce your exposure to the sun. Now, that doesn't mean don't get your early morning sun to help your circadian rhythms and your sleep at night, but wear a long-sleeve shirt, put sunscreen on regularly throughout the day, and that can help reduce your risk of skin cancer. I mentioned certain viruses like the HPV virus and cervical cancer. Get the vaccines to prevent those infections. So HPV and hepatitis B vaccines are part of the routine kids' immunization schedule. So make sure that your kids, grandkids are getting those. And here's one of my favorite ones: exercise. As we know, exercise helps prevent stroke, it helps prevent heart attack, it helps prevent cognitive decline. Guess what? It has an apparent uh connection to cancer as well. In a large study where they combined a bunch of smaller studies, they had over a million people and they looked at how much they exercised and the risk of 26 different cancers. And when they compared the people who did a lot of exercise versus very low exercise, the high exercise people had a 10 to 20 percent lower risk of colon cancer, lung cancer, breast cancer, and other cancers. Now, like a lot of observational studies, they didn't adjust for everything. So maybe the exercise people were skinnier. And as we've talked about, being overweight is related to cancer. So it's possible it's not just the exercise solving the problem or helping the problem. It may be mediated through weight loss. If you can exercise, if you can get your weight under control. But here's a really neat study that was done in colon cancer patients. So these people already had colon cancer, but they got treated and they were in full remission. They followed these people for eight years and they divided them in a randomized way into an exercise group or a not no additional exercise group. And what they found was a 30% reduction in recurrence of the colon cancer in patients who underwent the exercise regimen. That's amazing. Now, obviously, we don't all have colon cancer, but I believe it says something about cancer in general, and I'm obviously very bullish on that in terms of exercise. Okay, number six here, you might consider dietary changes. In my episode number 47 about organic foods, I described some studies that compared people who ate five servings of fruits and vegetables a day versus two servings. And guess what? The people who had the more fruits and vegetables, they had a one-third reduction in cancer. Of course, this is confounded. We don't know did they fully adjust for, you know, people who eat a lot of fruit and vegetables might be eating fewer Twinkies and croissants, and therefore those people might have been skinnier. So we can't disentangle that, but more fruits and vegetables seems like a thing we should try to do, and the data supports it. There's also data on your diet related to fiber and colon cancer. There's a large meta-analysis done in the journal Lancet that looked at a whole bunch of observational studies, but also 58 randomized trials. And what they found was the cancer rate, the colon cancer rate, was 3% lower for every 15 grams of fiber that people had. So ideally, you'll get something like a cup of lentils a day, or a couple of cups of beans or oatmeal. That kind of amount would be very, very potentially helpful to reduce your risk of colon cancer. Again, confounded by issues of weight, because we know weight is a problem too. I have to at least mention again about the issue of bacon. Do listen to my episode on that, or alcohol, which is my episode 24. What else can you do? Well, if you're in an air pollution-laden area, you're living in a city where that's likely to be the case, you can get a HEPA filter in your home. And it does get rid of some of the particulates in the home. There are no clinical trials showing reduction in cancer, but it's something if you wish you might consider. We don't have HEPA filters here, but then we live on a ranch and uh we're not exposed to too much pollution. And lastly, that one of the things you can do is get your HPV vaccine and your hepatitis B vaccine. All right, step four. Don't ignore new symptoms. If you notice a lymph node or a lump somewhere, if you have blood coming from a place that it shouldn't be, like you're coughing blood, you're peeing blood, you have blood in your stools, there's blood that might be uh coming from your vagina. Even if it's tiny amounts, don't ignore it. Go see your doctor, get checked out, because it could be an early warning sign of cancer. And just because the bleeding stops, oh, I bled for a day or two, but then it went away, that doesn't mean it's not something serious because cancers bleed intermittently. All right, step five, screen. Get your cancer screening for the items that make sense. So for women, obviously a mammogram and a pap smear. For a man, potentially a PSA, but that's a whole nother topic. Talk about that with your doctor. Colonoscopy used to be age 50 or 55, we began. Now the recommendations at now 45. So get your colonoscopy screenings if you're in that age range. If you're a smoker or an ex-smoker, then a periodic CT scan of your lungs has been shown to be beneficial. Screening for other cancers are tough. I mean, ovarian and pancreatic, of course, you want to avoid those. But there's no good screening recommendations for general avoidance. However, if you have a family history of those illnesses, there are special screening protocols that might be appropriate for you. Talk to your doctor. All right, what about that highly advertised total body MRI that will look at you from head to toe and find all those little things that might be cancer? Listen to my episode on number 12 on to test or not to test. I talk about this directly. For a typical person without symptoms, it's likely to cause more problems than it's going to solve. And finally, in the screening world, you hear about these liquid biopsies. Take a blood test. We will determine if you have one of 30 or 40 cancers. You will then catch it early. The promise is there. The idea is wonderful. And these blood tests can be positive when you have cancer. What hasn't been shown is whether it makes a difference in your outcome, in your survival. But there haven't been the studies to say people who did the test compared to people who never did the test. Did the people who had the test live longer, have fewer advanced stage cancers? That's the study we need to see. And in the advance of that, I don't suggest people spend$1,000 on the blood test because it isn't just a once-in-a-lifetime thing. Do you have to do it every year? Do you have to do it every six months? How quickly does the cancer go from not present to present? So I think it's not yet ready for prime time, although I sure hope at some point it is. The final step to reduce your risk of cancer. Be aware of what doesn't reduce your risk. You know, on the radio, on podcasts, in the news media, supplements, supplements, supplements, they will reduce your risk of cancer. Bottom line is the studies don't support that. Omega-3s have been tested a lot in observational studies and in other types of studies, it doesn't seem to help. Antioxidants like beta-carotene. There's been multiple large randomized controlled trials, no benefit. Vitamin D, 25,000-person RCT, the vital study, tested vitamin D, omega-3s, didn't help. I will have the links to these in the show notes, so by all means take a look. Vitamin C was touted as a great preventative for cancer. Meta-analysis of seven RCTs, no benefit. Some people thought aspirin might prevent cancer. Large study in the elderly, no big difference. Sorry about that. I wish it would help. Okay, time to wrap up here. Cancer is a frightening diagnosis, and we want to avoid it if at all possible. As I said at the outset, the good news is 40% of the cases are in fact preventable. So find your risk factors and do what you can. It might be smoking, it may relate to protecting yourself from the sun, it may be weight control as best as you can. Do get appropriate screening absolutely to try to find any of those cancers that you can screen for in an early phase possible. 60% I said are not preventable. Gail, my dear wife, got uterine cancer, metastatic, and she had zero risk factors. So it can happen to you. If it does, I have my episode on navigating a serious illness that might help you kind of work your way through that journey. As always, I hope you live long and well and do what you can to reduce your cancer risk. Thanks so much for listening to Live Long and Well with Dr. Bobby. If you like this episode, please provide a review on Apple or Spotify or wherever you listen. If you want to continue this journey or want to receive my newsletter on practical and scientific ways to improve your health and longevity, please visit me at Dr. Bobby Livelongandwell.com. That's doctor as the dr bobby livelongandwell.com.