I have railed against pseudoscientific charlatans who claim that they have the easy method for cancer prevention. Generally, these snake oil salesmen try to convince you that they have some magical food, supplement, or lifestyle change that can either kill cancer in its tracks or keep them from even growing in your body.
Of course, none of their claims are actually supported by robust science. On the other hand, real science has 12 evidence-based methods actually to prevent cancer.
But what about those memes that say that supplements prevent cancer? Nope, they don’t. And that’s been shown in study after study after study after study (yeah, I could go on for a while).
How about avoiding GMO foods because they cause cancer? Again, studies show that GMO foods have no effect on cancers. Oh, one more thing – bananas don’t have tumor necrosis factor, and the yellow fruit can’t prevent or cure cancer (but that doesn’t mean that they aren’t delicious).
Despite the absolute lack of evidence that supplements, kale, bananas, or drinking the pure waters of a glacial-fed stream (which may not be an option with climate change) are important to cancer prevention, there are science-based methods that I am going to discuss.
How to prevent cancer has been codified by the World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) into 12 steps (no, not that debunked one) that are called the European Code Against Cancer.
Let’s look at cancer and how to prevent cancer.

What is cancer?
There are so many myths about cancer – I have dispelled many of these myths. However, let’s discuss some science-based basics about cancer.
Simply, cancer is a disease in which cells of the body grow in an uncontrolled way, forming a tumor that may spread to different parts of the body. There are around 200 types of cancer, though the exact number is not precisely known, since some cancers may be related to others, or may not be cancers at all.
The National Cancer Institute states that there are over 100 types of cancer. Cancer Research UK states that there are over 200 types of cancer. The American Cancer Society lists over 70 types of cancer (although some are more classes of cancer rather than a single type). Wikipedia lists over 180 different cancers.
I need to make this clear because too many people think that “cancer” is one disease with one cure. In fact, each cancer has a different etiology (cause), pathophysiology (development), prognosis, and treatment. There will never be one cure to cure all cancers, but there will be thousands of treatments for hundreds of different cancers.
All cancers are caused by mutations in the DNA of cells in the body. Most of the time, cells deal with these mutations by “fixing” the DNA. Or the mutation is so serious that the cell simply dies (it’s really one cell, and cells die in your body constantly). If the mutated cell lives and divides, the body has immune defenses against most mutations — so it’s gone before you would even know that it’s there.
For cancer to survive from a single cell to a mass of cells, requires nutrition (forcing the body to feed it with blood vessels). To do that, it needs another mutation of the cell. Then it needs to grow unrestricted by the normal growth control systems of the body–another couple of specific mutations. Cancer also needs to hide from the immune system and more mutations.
Cancer usually requires numerous, possibly up to 10, independent genetic mutations in a population of cells before it can become a growing, metastatic cancer. Each mutation is selected, as in what we call natural selection because it provides some benefit to the cancer cell, such as causing blood vessels to supply the cells for nutrition and oxygen, or the ability to divide rapidly, whatever the feature is.
Again, with trillions of cells, it becomes mathematically possible but very hard to do. Let’s look at cancer from a strictly mathematical point of view – it’s really really really really really rare. To pile up that many mutations that all are advantageous to the cancer cell are almost unimaginable.
These mutations can have a lot of different causes. The environment (like smoking or UV radiation), viruses (hepatitis B and human papillomavirus are the most common), and genetics all can contribute to an increased risk of cancer. However, about 67% of all cancers have no cause and result from random mutations in the genome of a cell.
Technically, with 46-68 trillion cells in the average human body, even if a cell mutation is extraordinarily rare, the law of large numbers means that you could have literally hundreds of thousands of cancer cells living in your body, dying naturally, or being destroyed by the immune system, or not causing any problems at all. There are just so many cells in the body, and because the cellular replication mechanism is slightly less than perfect, mutations will happen.
And there is nothing you can do about these random mutations. You can drink your blueberry-kale smoothie every single day of the week, and these mutations will happen.

Just to make it perfectly clear, outside agents, like infections, tobacco smoke, radiation (more broadly than just radioactive energy, but ultraviolet and other types of radiation), and human physiology can cause (or allow to cause) so many mutations that eventually one leads to an increase in the number of mutated cells, then a growing viable cancer.
You may not be able to prevent all cancers, but you can reduce your risk of cancer. When a scientist states that something is linked to cancer, we need to refrain from considering it an on/off switch. For example, there are people who smoke cigarettes their whole life and never get lung cancer (see Note 1).
Whenever I read some internet pseudoscientists claiming that there is a cure for all of the different forms of cancer, I laugh because I know that they actually don’t understand the nature of cancer. Maybe someday, well into the future, we might have some scientific “ah-ha” moment, and we find a common link between all cancers, but that seems implausible. Until there is overwhelming evidence that there is one cure to cure all cancer (and there isn’t any), you should know that we wage war on cancer, one at a time.

Cancer prevention in not-so-easy 12 steps
- Stop smoking tobacco. This is the number one way to reduce your risk of cancer–smoking causes lung cancer, which is the #1 cancer killer in the US and Europe. Smokers are 15-30X more likely to contract and die of lung cancer than non-smokers. This isn’t something that we’ve known just for a couple of years, but since before the 1950s. And it’s not just smoking tobacco that increases the risk of cancer–using it in other forms, such as smokeless tobacco can contribute to significantly higher risks of cancer. But the good news is that the sooner one quits using tobacco products the better the long-term prognosis. Studies have shown that smokers who quit at about age 30 reduce their chance of dying prematurely from smoking-related diseases by more than 90 percent.
- Avoid second-hand smoke. Even if you avoid smoking personally, second-hand smoke has nearly the same health risk, depending on the frequency of encountering smoke. In the USA, inhaling cigarette smoke, unless one is a smoker, has become relatively rare. But in Europe, even with official bans on smoking, the risk of encountering second-hand smoke can vary by country and location from 31-90%.
- Maintain a healthy weight. Keeping one’s BMI between 18.5 and 24.9 kg/sq m can lead to an 18% lower cancer risk. Scientifically, it is possible that other confounding factors, for example, a high-fat diet or smoking, may lead to a higher risk of cancer being associated with obesity. Still, the evidence seems to show a possible causal relationship. Besides, obesity leads to a much higher risk of heart disease, joint problems, and other medical issues, so being thin has a lot of health benefits.
- Be physically active. Closely related to #3. Being physically active helps maintain a healthy weight, but it may have other benefits with respect to cancer risks.
- Eat a healthy diet. No, this does not mean that consuming blueberry-kale soy milk smoothies reduces the risk of cancer. However, as IARC states, eating a diet filled with whole grains, fruits, and vegetables while avoiding high-fat and high-sugar foods will help with #3. There’s no solid evidence that a particular diet will reduce the risk of cancer, BUT a healthy diet can lead to weight loss and maintaining the appropriate BMI. I think there is growing evidence that the Mediterranean diet has a direct link to longer lifespans so it might be a good choice.

- Avoiding alcohol. Alcohol, even in moderate amounts, can lead to a significant increase in the risk of certain cancers. In fact, alcohol consumption causes around 3% of cancer deaths in the USA. And not to repeat a point – reduced alcohol consumption could lead to weight loss and a healthy BMI.
- Avoid the sun (and UV tanning beds). Ultraviolet (UV) light, usually sunlight, can damage surface skin cells leading to some severe cancers. Although one form of UV light, UVB, is necessary for the production of vitamin D, an essential nutrient, excessive UVB can permanently damage cells. Getting vitamin D through supplements or foods is probably healthier than sunlight (yes, I recommended a supplement, because I always make an exception for valid medical reasons like chronic disease or malnutrition).
- Avoid pollutants. Some believe that all “chemicals” are bad, even though there really are just a few that are known carcinogens and should be avoided. The current “chemophobia” of many people is borderline ridiculous because even known carcinogenic chemicals can only increase the risk of cancer at certain levels, meaning they could be safe in meager amounts (dose makes the poison in toxicology). It’s all about the dose. It’s impossible to avoid all man-made and natural chemicals (there are more so-called natural substances that are carcinogenic than humans could possibly invent), but avoiding polluted water and air, or being careful in a workplace that has a lot of chemicals, will help manage the risk. Remember, the theory (from a scientific perspective) that cancers arise from frequent mutations means that the risk increases as the number of mutations increases. The world isn’t perfect, but it’s not either no chemicals or “we’re all going to die of cancer” type of false dichotomy.
- Avoid radiation. This risk is just radon gas, an invisible radioactive gas found in many homes in certain geological formations. There are other risks to some people who may be exposed to radiation in specific careers. Radon can be easily detected and easily removed from the air, but it does require testing. Many people would not rent or buy a home without thoroughly testing it for radon gas – I wouldn’t buy a home without testing for radon.
- Breastfeed your baby. Women who breastfeed their babies for extended periods of time reduce their risk of breast cancer in later life when compared to women who do not breastfeed. In fact, the reduction in risk of breast cancer is about 4% for every 12 months of breastfeeding (which can be summed up over more than just one baby). This reduction in risk is above and beyond the reduced risk of breast cancer from having a baby.
- Get your HPV and hepatitis B vaccines. It’s ironic that the pseudoscience pushers are solidly anti-vaccine, yet promote pseudoscientific and unsubstantiated “prevent cancer schemes” that are useless. On the other hand, two vaccines, for hepatitis B and HPV, actually prevent more cancer than drinking 100 blueberry-kale soy milk smoothies. The hepatitis B vaccine has caused a 96% decrease in hepatitis B infections, which are related to over 50% of the cases of a type of liver cancer, hepatocellular carcinoma. The HPV vaccine blocks infection of the human papillomavirus which is linked to several types of terrible cancers. Despite the myths, the HPV vaccine is incredibly safe, possibly the safest vaccine of all vaccines (which are all extremely safe). Seriously, one could swallow hundreds or thousands of supplements, and these vaccines will actually do more to prevent cancer than those overpriced supplements will ever do. And yes, the scientific evidence supports that statement.
- Get screened for cancer. There are diagnostic screenings available for a huge number of cancers. One can get a colonoscopy for hard-to-detect intestinal cancers. There are simple screenings for cervical and prostate cancer. There is imaging for small tumors on internal organs. There are blood tests for others. Yes, getting a colonoscopy, if you’re age-appropriate, is not fun. But it’s not dangerous, and it can detect cancer very early before it kills. Once again, screening is much more effective than the mythical miracle kale smoothie.
Prevent cancer
- Preventing and treating cancer is not as easy as the “natural food and supplement” people claim. It’s because they oversimplify and understate the biology of cancer. They want people to think “take this pill, don’t worry anymore.”
- Cancer incidence and mortality are dropping. Modern, science-based medicine is the cause.
- Stop smoking.
- Lose weight.
- Get out of the sun.
- Don’t drink carcinogens.
- Make sure your house has no radon.
- Breastfeed your baby (if you’re a woman of course) for as long as possible.
- Get the hepatitis B and HPV vaccines.
- Get regular screenings for cancer.
I know. It’s not really that easy, probably not as easy as downing $20 of supplements that will just be passed in the urine. But if any of you really want to reduce your risk of cancer, then you’ll have to do this. Or just drink your kale shakes. At least that will make you lose weight.
Notes
- Just because some people may not get lung cancer from cigarette smoking does not mean I, or anyone with more than three functioning neurons, believe that it is safe. Individuals who smoke are 25X more likely to be diagnosed eventually with lung cancer. Furthermore, smokers are much more likely to contract other deadly types of cancer, to develop long diseases, and to die of cardiovascular disease. It’s a stupid habit that will kill.
Key citations:
- Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years’ observations on male British doctors. BMJ. 2004 Jun 26;328(7455):1519. Epub 2004 Jun 22. PubMed PMID: 15213107; PubMed Central PMCID: PMC437139.
- Edwards BK, Noone AM, Mariotto AB, Simard EP, Boscoe FP, Henley SJ, Jemal A, Cho H, Anderson RN, Kohler BA, Eheman CR, Ward EM. Annual Report to the Nation on the status of cancer, 1975-2010, featuring prevalence of comorbidity and impact on survival among persons with lung, colorectal, breast, or prostate cancer. Cancer. 2014 May 1;120(9):1290-314. doi: 10.1002/cncr.28509. Epub 2013 Dec 16. PubMed PMID: 24343171; PubMed Central PMCID: PMC3999205.
- El-Serag HB, Rudolph KL. Hepatocellular carcinoma: epidemiology and molecular carcinogenesis. Gastroenterology. 2007 Jun;132(7):2557-76. Review. PubMed PMID: 17570226.
- Kort EJ, Paneth N, Vande Woude GF. The decline in U.S. cancer mortality in people born since 1925. Cancer Res. 2009 Aug 15;69(16):6500-5. doi: 10.1158/0008-5472.CAN-09-0357. PubMed PMID: 19679548.
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