Helpless to Prevent Cancer? Actually, Quite a Bit Is in Your Control
Americans seem very afraid of cancer, with good reason. Unlike other things that kill us, it often seems to come out of nowhere.
But evidence has increasingly accumulated that cancer may be preventable, too. Unfortunately, this has inflamed as much as it has assuaged people’s fears.
As a physician, I have encountered many people who believe that heart disease, which is the single biggest cause of death among Americans, is largely controllable. After all, if people ate better, were physically active and stopped smoking, then lots of them would get better. This ignores the fact that people can’t change many risk factors of heart disease like age, race and family genetics.
People don’t often seem to feel the same way about cancer. They think it’s out of their control. A study published in Science in January 2015 seemed to support that view. It attempted to explain why some tissues lead to cancer more often than others. It found a strong correlation between the number of times a cell divides in the course of a lifetime and the risk of developing cancer.
In other words, this study argued that the more times D.N.A. replicates, the more often something can go wrong. Some took this to mean that cancer is much more because of “bad luck” than because of other factors that people could control.
Unfortunately, this simple explanation is not really what the study showed. Lung cells, for instance, divide quite rarely, and still account for a significant amount of cancer. Cells in the gastrointestinal tract divide all the time and account for many fewer cancers. Some cancers, like melanoma, were found to be in the group of cancers influenced more by intrinsic factors (or those we can’t control), when we clearly know that extrinsic factors, like sun exposure, are a major cause.
Further, this study was focused more on the relative risks of cancer in one type of tissue versus another. What we really care about is how much we can reduce our own risk of cancer by changing our behavior.
A more recent study published in Nature argues that there is a lot we can do. Many studies have shown that environmental risk factors and exposures contribute greatly to many cancers. Diet is related to colorectal cancer. Alcohol and tobacco are related to esophageal cancer. HPV is related to cervical cancer, and hepatitis C is related to liver cancer
And you’d have to be living under a rock not to know that smoking causes lung cancer and that too much sun can lead to skin cancerUsing sophisticated modeling techniques, the researchers argued that less than 30 percent of the lifetime risk of getting many common cancers was because of intrinsic risk factors, or the “bad luck.” The rest were things you can change.
