The Biggest Myth About Cancer: That It Just “Happens”

There are many persistent myths about cancer and cancer prevention, but central among them is the assumption that cancer “just happens”. This is fallacious. How you live and what you choose to put in your body has a direct – and significant – causative relationship to whether or not your risk for cancer will be elevated.

Cancer isn’t an overnight event – it develops most frequently over many years due to a range of factors. A fascinating review of over 7,000 studies (talk about thorough) finds that what you eat and how fast you grow are perhaps most significant. I’ve long said that the fuel you serve your body impacts 70% of your health (the rest is exercise and stress management). But it’s interesting, especially in light of our Primal Health explorations, to consider the role of growth – and by growth researchers are talking about hormones.

The surest way to minimize your risk for all cancers is to practice a healthy lifestyle:

– do not smoke

– drink alcohol in moderation

– eat copious produce (this should be the “bulk” of your diet)

– do not eat processed, fried, junk, or refined carbohydrate/grain foods

– absolutely avoid sodas and sweetened drinks

– avoid corn syrup, cured and/or heavily processed meats, and corn oil

– do not eat trans fat or canola oil

– eat “clean”, lean protein  (organic, grass-fed, free-range, etc.)

– eat “smart” fats (wild fatty fish, fish oil pills, avocados, nuts, olive oil, purslane)

– mothers, breast-feed your baby if possible

– exercise

– get daily sunlight exposure!

– get plenty of antioxidants from your diet and supplements

– avoid hormone therapy unless medically necessary

– manage stress to regulate hormones appropriately

Further reading:

16 Ultimate Super Foods

Smartest Foods to Boost Your Brain

44 Amazingly Healthy and Delicious Naturally Low-Carb Recipes

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About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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33 thoughts on “The Biggest Myth About Cancer: That It Just “Happens””

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  1. Great post, as unfortunate as cancer is and ever growing number of people are affected…people need to realize they have total control of their health. Otherwise what kind of life is that destined to be sick by our own genes? I don’t choose that road as much as modern “sick”care would have me believe. Cancer is a gigantic industry…as there are billions of dollars to be made through drugs and treatments. I would also add above periods of fasting (cell cleansing and rebuilding) and plenty of raw fruits and vegetables (enzymes). Also removal of as many toxins from our environment as possible.

    1. You’re surely not serious!??? By saying this you are implying that if you have cancer it’s your own fault, which is not true. Yes your chances of avoiding cancer are improved by leading a healthy lifestyle, but the truth is that there is chance involved. The most health-conscious person can still get cancer if they are unlucky, despite their best efforts.

      1. you are what you eat drink and do. genes load the gun. it does not pull the trigger thats yourself.

        if you eat crap all day. and drink sodas (liquid candy) your risk is 50% that you agree to develop a decease.
        genes load the gun. but the environment pulls the trigger

        1. Yes you are what you eat. However you can still be paleo for 10+ years, eat only organic, exercise regularly and still get cancer. Happened to me and I’m only 27. Not always your fault.

  2. Maybe this is a bit of a semantics exercise, but I question the often repeated advice to avoid “fried” foods. Am I wrong in thinking that there’s noting wrong with the method of cooking, but rather with the oil used to do the frying? I “fry” a lot of meals but I use olive oil exclusively to do so.

    1. too much olive oil has also a negative effect. a person only needs a lil bit.
      once in a gray while it doesnt hurt tho

  3. Canola and Corn oil… I thought they were neutral–not especially good for you but not especially bad. What makes them something to avoid?

    1. These oils are high in Omega-6 fatty acids which, in excess, promote inflammation, which in turn spurs cancer growth and spread. For some reason, corn oil is particularly bad in terms of cancer. I believe I read this inNatural Strategies for Cancer Patients by Dr. Russell Blaylock, but I am fairly certain I recall getting literature from a hospital nutritionist after my cancer diagnosis about this. It compared tumors in mice fed corn oil vs. walnuts and showed much faster rate of tumor growth in the corn oil mice, as I recall.

  4. Dave, I was thinking the same thing. I hope someone can share some more information on this. I mean if you were to fry something in coconut oil for example would that truly be bad for you? If your talking vegetable oil though then yes that is awful for the body. Hope someone has more info regarding fried foods.

  5. I saw you on know the cause. I learned alot about your master formula. My husband just had surgery and they found cancer. The cancer has spread to 70% of his liver. He now wears a bag on his stomach to bypass his liver till he heals. They just started chimo today. The doctor put him on a low fiber diet, the opposite of what he need to fight the cancer. He could have this low fiber diet for up to six months, as long as he has the bag. What can I do to help him health wise.I can’t feed him a raw vege. diet or even whole grains at all. I’m at wits end. He’s been given a 30-40% chance of living. I know we have a big God and I know he’s healed but seeing him 60 lbs. down in weight and so yellow, I just want to help nutrition wise. Can you give me some advise? God bless you, Tamela Johnson

    1. I know this is a bit late, but here is my recommendation.
      Milk Thistle, Raw Liver Powder, buy a juicer and start juicing raw vegetables, don’t worry about the plant toxins at this point, the alkalinity of the plants will fight cancer, also some people inject Baking Soda into themselves (which is a bit extreme), eat glands, especially the liver of animals. Garlic and onion cleanses blood.
      Drink pure, clean mineralized spring water with all minerals and trace minerals.

      The cure for cancer was found in 1928 by Dr. Max Gerson. His clinic is located in Mexico now because the United States banned his alternative 100% success rate method.
      The Gerson Clinic cures ALL forms of cancer, even in its latest stages. People come from all over the world, hanging onto their last thin line of life, to get help there.
      He wrote a book and a documentary exists, also online you can read up on how to do it at home.

      One of my meat suppliers had stage 3 prostate cancer and cured the cancer within a few months.

      Good Luck!

  6. This is a worthless and disingenuous “study”. It follows the same patterns of poor practice that so many seem to do nowadays. It reviews only epidemiology, and unscientifically attaches cause to association. It vastly over inflates non-significant associations, based on the modern obsession with being more concerned with needing to make a clear and simple public message. They decide on significance, not on anything compelling but on “probability” estimations, which are subject to current fashions about what is likely to be true. In fact, cancer triggers, even strong ones such as pollution and cancer, are much less significant than factors such as immune sufficiency. A diet that promotes high immune function – such as the high animal fat, low carb Paleo/traditional whole food diet – will protect against all cancers because it make the body strong. Any diet that weakens the body (most easily seen in symptoms such as obesity and its related syndrome – x complexes) is going to promote cancer. More to the point, the study avoids any discussion about the growing evidence that vegetable oils, promoted to replace saturated fats, are cancer promoting – because they depress the immune system and are prone to oxidisation.

  7. OK, lets get one thing clear right from the start, correlation (association), never implies causation, ever. It doesn’t matter how much the media and other people with vested political interest’s wish to make it causative, it isn’t. Secondly, lets add a little perspective, according to the latest data from the CDC colon cancer affects 51.2 out of 100,000 people in the U.S.. So pardon me while I enjoy my slim jim and raise my probability of getting colon cancer from 0.05% to 0.0575%.

  8. When I first read that WCR/AICR press release I worried it was going to end in a flurry of blame-the-victim thinking wrt cancer. I’ve known a number of young and clean-living people who’ve gotten cancer over the years and I hate the thought of people looking at kids and young adults like that and thinking there must’ve been something they did to deserve it.

  9. Moe and Jerry-I avoid canola and corn oil and other poly-unsaturated fats. Canola is made from the rape seed and is highly refined and cheap. Corn is just wrong. I don’t see the health benefits. Coconut oil is 100% saturated fat and is healthy. Eat away. I sometimes cook with olive oil but try to eat it unheated like on my salad.
    Kim- Nobody deserves cancer.

  10. Lots of great comments here and several directions to go in. I’ll briefly address what I can and we can hopefully keep exploring this issue in this thread.

    Mike OD, your comment about genes strikes a chord.

    Dave C, nothing necessarily wrong with frying; I’m talking about deep-fried, breaded junk and should have been a bit more clear on that. I often pan fry fish and chicken.

    Moe and Jerry,

    A bit of clarification on canola oil. While we don’t buy into the urban legends about rapeseed (which are utterly spurious), there are some concerns. That said, by grouping canola oil with trans fat, I was implying the need to avoid fats that can become pro-oxidants and of course to avoid all hydrogenated fats like the plague. Canola oil itself can be healthy and is considered by many health experts to be one of the best fats; then again, the reigning fat researcher, Mary Enig, whom I really respect and admire, does not recommend canola oil. A couple of considerations: canola oil, being so unsaturated, is highly unstable. It can become rancid, and thus a pro-oxidant, very easily (as can any unsaturated oil). That’s the concern. Canola oil needs to be handled very carefully to ensure that this doesn’t happen. Still, some experts, Enig among them, posit that any expeller-pressed oil is not only refined to some extent, but that by exposing an unstable unsaturated fat to high heat during cooking, any purported benefits may become counter-productive. I’m not necessarily “against” canola oil – merely cautious about taking a definitive stance until we know more. Having weighed the evidence, I simply think it’s wise to know what we’re getting into with certain fats, especially vegetable oils. That said, I should have clarified that by “trans fat and canola oil” I had the middle-aisle junk foods and chemically-loaded salad dressings in mind.

    Tamela, my heart goes out to you. There is a wealth of nutrition information here that I hope can be of help to you. Try selecting (clicking) the “Nutrition” category in the right sidebar of this page for more articles. We wish you and your husband all the best. Keep us posted.

    Markus, I agree with much of what you say, particularly with your comments about immunity and the paleo (around here, “primal health”) dietary philosophy. We are being bombarded constantly with all manner of bacteria and viruses, and it is our opinion on this site that the single biggest factor in reducing your cancer risk is to support the immune system. However, I have to defend epidemiology a bit. Epidemiological studies do offer some value – they are not entirely worthless. They are a necessary starting point in many cases. They don’t always “prove” something – they can’t. But they can offer insights that are of merit. Your point is well taken, however, epidemiological studies are about reducing risk, not prevention. There are no guarantees. We have to look at what our lifestyle is, and this really ties back to the Primal Health concept. That is, to look at how we are supposed to live and eat (the original prescription for the human body as revealed by evolutionary biology, genetic research, and so forth) in the context of the modern world, when it is sometimes impossible to make the ideal choices that the human body’s blueprint really requires. The great challenge here, for all of us, is understanding how our choices impact us, what the consequences are, and perhaps most importantly, what the implications of compromises are.

    Kevin, I’d simply reiterate that while correlation isn’t causation, that doesn’t mean there is no value in such an analysis. I subscribe to the concept of following a higher-fat, higher-protein diet than our national guidelines recommend. Though I personally recommend grass-fed (I want those Omega 3’s) and minimally processed meats to get there. A slim jim may not, by itself, be a grave danger, but in the aggregate, we have to at least understand and be aware of the multitude of factors compounding to reduce our immunity and impair our ability to fight disease.

    FWIW, I don’t have a problem with red meat or fatty cuts of meat, but I encourage people to keep it “lean” in the sense that knowing saturated fat is not a death sentence does not give us carte blanche to slap the 48 ounce porterhouse in the grocery cart because it’s on sale.

    Kim, I’m glad you shared your perspective. You make a very important point.

  11. @Dave C:

    As others have noted, the problem with frying is the oil. Besides the damage caused in refining vegetable oil, heating any oil/fat to its smoke point creates harmful oxidized fats. Fats and oils that are high in saturated fats like butter, tallow, lard, coconut oil, and peanut oil withstand heat better than monounsaturated and polyunsaturated vegetable oils. I never cook anything on the stove at a temperature higher than medium heat and saute in water or broth whenever possible. Once a month I toss some soup bones from pastured animals in a slow cooker and store the broth in small glass jars in my freezer.

    Kevin, colon cancer may affect only 51 out of every 100,000 Americans, but all cancers combined will strike one out of every three Americans. Diet is linked not only to colon but also breast, prostate, pancreatic, and even lung cancer. It would be easy enough to say “go ahead, it’s your body,” except for the fact that Americans’ poor health habits are ONE reason my single health insurance costs $400 a month.

  12. You can read the report here:

    It’s over 100 pages long, but it’s broken up into chapters, so you don’t have to view the whole thing. The chapter on food and drink is definitely worth a look. The authors compiled the data into easy-to-read charts classifying foodstuffs into columns labeled “decreased risk” and “increased risk” and further classifying by strength of evidence, “probable,” “suggested,” or “unlikely.” The specific types of cancers were also listed in the charts. In a nutshell, non-starch vegetables generally confer a decreased risk and red meats an increased risk. Dairy studies are mixed while there is limited/suggested evidence of increased risk of a few cancers with fats and sugars.

  13. Sorry to contradict you but indeed frying is unhealthy per se. Only fried veggies are not that unhealthy but esecially with meat frying with whatever oil form cancerogenous substances and destroys the highest amount of nutrients.
    Grilling and frying are the worst cooking method that form toxic substances into food.
    Oil has nothing to do with it.
    Besides the oil with the highest smoke point is olive oil while butter has one of the lowest smoke point of all the fact and is therefore together with coconut oil the worst choice for frying.

  14. I agree that frying is unhealthy, and I don’t do it, but your smoke point information is incorrect. According to the website Cooking for Engineers, extra virgin olive oil has a smoke point of 320 F, lower than butter and coconut oil at 350 F. I’m not going to post a link because it will flag my comment into the spam trap, but you can find the page listing smoke points of various fats by googling “cooking for engineers” and “smoke point.” A quick scan of the page shows that unrefined oils with low saturated fat content have lower smoke points than oils high in saturated fats, which in turn have lower smoke points than refined oils,which are unhealthy period.

  15. And as for the comment that “oil has nothing to do with it,” please read this from the Cooking for Engineers webpage on oil smoke points:

    The smoke point of various fats is important to note because a fat is no longer good for consumption after it has exceeded its smoke point and has begun to break down. Once a fat starts to smoke, it usually will emit a harsh smell and fill the air with smoke. In addition it is believed that fats that have gone past their smoke points contain a large quantity of free radicals which contibute to risk of cancer.

  16. Still not buying it. The two biggest factors to cancer are still age and genetics. If you have a family history, then fine, maybe diet should be a consideration. For the rest of us, the individual risks are so incredibly small, that you’ll get better odds in Vegas. This type of research is useful for generating hypothesis’, but thats about it. In the case of red meat, the number of potential confounds is enormous. n-3 to n-6 ratio, sugar consumption, and refined flour consumption to name a few. It makes no distinction between a mcfatty burger , and a grass fed sirloin. IS it really red meat or just the source of the meat many people eat?

    A slim jim may not, by itself, be a grave danger, but in the aggregate, we have to at least understand and be aware of the multitude of factors compounding to reduce our immunity and impair our ability to fight disease.

    1. the source of meat definitly plays a role. like i always say genes load the gun but yourself pulls the trigger. and a lot of common sense. and you are what you eat plays a big role. if

  17. Corn, soy, canola, and cottonseed. The preponderance of these crops grown in the US are genetically modified.

  18. This is blaming the victim. The study is fundamentally flawed – it examined only (quote from Chapter 3 of the report)
    “evidence that aspects of food, nutrition, physical activity, and body fatness can modify the risk of cancer”.

    Since they did not control for the rest of the environmental factors, and ignore the differences between the US ‘red meat’ that contains a cocktail of antibiotics, hormones, steroids, and other chemicals: and let us say organic grass-fed beef: I really can’t put much faith in their conclusions.

    In fact that’s all they do – from the mission statement on their website,
    “Since 1990, World Cancer Research Fund has been supporting research into the role of diet and nutrition in the prevention of cancer.” Certainly diet and nutrition may play a role, but to suggest attention to these alone can prevent cancer, is an insult to all the cancer sufferers who have lived a healthy life. I knew three people who never smoked, ate well and exercised, yet died of lung cancer.

    How much of cancer is due to the quantities of chemicals in our environment ?,1,1963966.story?coll=la-headlines-health
    Maybe it’s melatonin deficiency ?,1,6192729.column
    Look at the list of factors here,
    Diet and exercise alone aren’t going to do it. Offering this as a panacea is dangerously wrong. You want to eat well and exercise because this improves the quality of your life, not because it will prevent cancer: it won’t.

  19. Olive oil should have the lowest “smoke point” of all publicly available oils because it contains the highest amounts of unsaturated fatty acids. Unsaturated fatty acids have less van der waals forces with each other due to the kinks in their chains caused by the double bonds that are responsible for “unsaturation” While saturated fats like butter have no kinks in their chains and so they can line up with each other and maximize the van der waals forces between each other and therefore have higher boiling points or smoke points.

    It is true that rancidity is a cause for concern and can cause problems in the body in large doses.

    Saturated fats are not better for you than unsaturated fats, saturated fats have a higher melting point and can aggregate in the blood vessels.

    Cancer is an incredibly complex illness that does have a lot to do with your genes. However cancer also has a lot to do with the things you put in your body. It would only make sense that in order to avoid cancer or to reap the benefits of being in good health would be to eat healthy, and exercise.

    Some of you are being way to polar on your view of clinical studies. Double blind clinical studies are a great resource, they can tell you whether something works or not, or things that are correlated to one another. Double blind studies have their own limitations, and as many have said, correlation is NOT causation.

    Statistics are important and they really do reflect the real world quite accurately, unfortunately some statistics are misrepresented, either purposefully or not it is each individuals job to do their own research on dubious statistics. We are lied to all the time it is our responsibility as intelligent individuals to check the facts and call people out on their lies.

  20. I get so angry when I see this type of drivel.
    It leads to the mistaken belief that illness is ‘deserved’ to some extent.

    It is well established that there is a causative link between tobacco smoke and cancer. This doesn’t mean all smokers will get cancer. Nor does it mean that avoiding cigarettes will guarantee being cancer free.

    There are many causes and risk factors involved in the many types of cancer which we simply aren’t aware of. Of those we know, not all are within our control.
    Cancer is not judgmental. It doesn’t care if you have done “everything right”. It’s a horrible disease which nobody deserves no matter what they have or haven’t done. This isn’t a good reason to not strive to avoid the risk factors you can but it is a good reason to stop judging cancer. Disease is amoral. People get cancer. They deserve compassion from themselves and everyone else.

    1. smokers and smoking. ofcourse your not developing cancer overnight. but you know very well you have yourself on the list. and if you do get cancer. do you blame something else or its someone elses fault?

  21. It is a great list of anti-cancer properties – however if you look here:

    You will see that cancer is actually caused from free radicals – free radicals is what mutates the DNA and causes cells to not function as they would normally – a large amount of mutated cells = cancer!

    To get rid of those mutations (which are in everyone to an extent!) you need super-antioxidants – not just any!

    The article above explains this in details and I hope this contributes to creating awareness of people who do not know this.

  22. I don’t smoke, but I’d rather die at 60 from a life of cigarettes and whiskey than worry every second of my life about dying early from cancer.

    The purpose of life is not life piled on life.

  23. Dear Mark, I have been on paleo for over a year, trying to get keto a few times, without success, unfortunately… I have seen the benefits of not eating grains and sugar even on my children, suffering from allergies before..
    The world nowadays is not paleo oriented, rather its all crazy about vegan… it is everywhere around us…. not that I would intend to turn to vegan, however, recently I have read som history books, about WW2, hitler and co., and I ve come across a few articles about a doctor of his era, Otto Warburg, thanks to whom hitler turned to vegan, the doctor came to the conclusion that meat eating leads to cancer, together with excessive CO2 exposure, which Is a well known fact… I have read a lot about this link btw cancer and meat, but reading literature on paleo eating has opened my eyes… it is just, that it is so in contrary to the theories about the dark side of paleo, that I am getting scared again, which is, what the world want us to be, scared… have you read any literature which would be contrary to the theory of cancer exposure eating too much meat, please?! thanks so much, Maria

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