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Key points
- Roughly two-thirds of all cancers are caused by naturally occurring DNA mutations accumulating as we age.
- Most people believe, however, that most cancer is caused by things "out there" in the environment.
- Risks that feel imposed, like environmental carcinogens, worry us more than those we engage in voluntarily.
- Excessive fear of external causes of cancer harms our health and society.
Part of a series on cancer phobia.
As fearful of cancer as we are, we are curiously selective about how we try to reduce that risk. We overreact about some potential causes of cancer while engaging in a range of behaviors that increase that possibility far more. Understanding this apparent irrationality is the first step toward reducing its hidden harms.
A recent report from the International Agency for Cancer Research (IARC) reinforces what we've known for a long time: Reducing or eliminating alcohol consumption decreases your risk of developing several kinds of cancer vastly more than many of the things we do to reduce that risk.
The benefit is enormous. After eliminating alcohol consumption for five to nine years, people enjoyed a 34 percent relative risk reduction for oral cancer and 55 percent after quitting for 10-19 years. For esophageal cancer, ceasing alcohol consumption for five to 15 years provided a 15 percent relative risk reduction, and quitting for 15 years or more yielded a 65 percent relative risk reduction. That's a similar magnitude of risk reduction to what smokers enjoy when they quit.
And it's not just oral and esophageal cancer. The study, a meta-analysis of dozens of individual pieces of research, found limited evidence that the same is true for the larynx, colorectum, and breast cancer.
Some may not take that advice, even though it comes from the International Agency for Research on Cancer (IARC). The same organization rates cancer risk from all sorts of things. When they even hint there may be a risk from some industrial chemical—glyphosate, PFAS, artificial sweeteners—we can overreact.
It is no surprise, really, this gap between our fears and the facts. Many like liquor, beer, and wine. Many also like fattening foods and sedentary lifestyles, too. However, reducing obesity can also cut your risk of developing cancer far more than avoiding "chemicals," "pesticides," and "radiation." These fear-inducing trigger words many associate with cancer risk automatically.
The IARC says red and processed meat is carcinogenic. That coffee (any beverage above 149 F), naturally occurring chemicals in the cooking of bread and cookies and french fries, and radiation from cell phone towers probably are. (A ton of evidence has disproved concern about cell phone radiation.) But many like bacon, coffee, cookies, chips, and fries, and we can be attached to our phones.
Why these selective fears? The research of Paul Slovic and others has found that we generally worry less about any risk that also provides a benefit and that we worry less about risks we take voluntarily than risks we feel are imposed on us. That may not be the most objective way to maximize our health and safety, but that's how the psychology of risk perception works.
This helps explain the findings of a 2015 public opinion survey by the American Society of Clinical Oncologists (ASCO) that asked people to rank the causes of cancer. Ten of the top 16 are imposed on us;
3. Radiation—89 percent (not including the natural kind from the sun)
4. Industrial pollution—88 percent
6. Asbestos—83 percent
7. Pesticides on produce—74 percent
8. Nuclear power—68 percent
9. Food additives—62 percent
10. Radon—59 percent
11. Genetically modified food—56 percent
16. Artificial sweeteners—51 percent
The voluntary lifestyle and diet choices that elevate our cancer risk far more showed up far down the list.
15. Being overweight or obese—52 percent
19. Alcohol use—43 percent
20. Lack of exercise—42 percent
21. Diet low in fruits and vegetables—42 percent
24. Diets high in red meats—35 percent
In a 2017 ASCO survey, 53 percent of people said "pollutants" were a risk factor for cancer, only 38 percent said "food choice," 31 percent said "obesity," 30 percent said "alcohol," and 25 percent said "lack of exercise."
These beliefs are the product of both our instinctive risk perception and magnification by the media. We waste money on products that promise to protect us from cancer but don't—more expensive organic fruits and vegetables (Cancer U.K.) or vitamins and supplements (World Cancer Research Fund International). We avoid artificial sweeteners or fret about cell phone radiation. We resist fluoridating our water or using non-greenhouse gas-emitting nuclear power to help fight climate change.
Yet many people eat bacon and chips, drink beer, and slouch on the sofa, binging on the latest popular show rather than walking around the neighborhood. This is curious, given that cancer has been our most feared disease since the early 1900s. Increasing lifespans finally helped us live long enough for the naturally occurring DNA mutations that allow uncontrolled cell growth to build up in our cells, which most cancer biologists say is the principal cause of the disease. Our diet and exercise contribute mightily to those mutations, far more than environmental carcinogens.
We can't entirely cure the fear of this disease any more than we can cure the entire disease itself. But we need to combat both because both are harmful. Knowing where our fear of cancer comes from can help.
References
This is part of a series of posts based on Curing Cancer-Phobia: How Risk, Fear, and Worry Mislead Us.
