Preventing Cancer Through Good Food and Exercise

A new report shows that three of the top preventable risk factors for cancer have to do with what we eat and how often we move.

In the American Association for Cancer Research's mammoth new cancer progress report lies the sad fact that about half of the 585,720 cancer deaths expected to occur in the United States this year are related to preventable behaviors. For a disease that often seems (and is) so senseless, it turns out that many cases can be avoided with lifestyle tweaks.

Smoking is the biggest one, associated with nearly 33 percent of preventable cancer diagnoses:

Top Preventable Causes of Cancer
American Association for Cancer Research

But as this graph shows, a combination of weight problems, poor diet, and exercise account for another third of all preventable cancers. Being overweight or obese is linked to colorectal, endometrial, gallbladder, kidney, pancreatic, and postmenopausal breast cancer.

The good news is that some kinds of cancer—like lung cancer—are on the decline. Others, though—like those of the pancreas, kidney, thyroid, and liver—are rising steadily.

"The cancers that are increasing are the ones that are associated with obesity," said AACR spokesman and University of Pennsylvania cancer epidemiologist Timothy Rebbeck.

Americans might be smoking less than ever, but obesity rates keep on climbing.

"These things are not independent of one another, so if you smoke and are overweight and are physically inactive, you have multiple hits," Rebbeck added.

The mechanism by which weight influences cancer varies by the type of cancer, but it has to do with the way a skewed body mass index disrupts the body's hormones, which then go on to disrupt DNA. "Obesity is also associated with inflammation, and cancer is a disease of inflammation," Rebbeck aid.

It would appear, then, that diet and exercise are nearly as important as not smoking when it comes to preventing cancer.

In light of that, it seems strange that this isn't more of a public-health message. Usually the warnings around obesity center on heart disease and diabetes—two scary diseases that are nevertheless far less scary than cancer.

Rebbeck confirmed that so far, the public-health message on obesity has tended to sidestep the cancer risk.

"There's been more education in the population about the link between obesity and diabetes," Rebbeck said. "In the cancer community, we've focused on things like smoking and going out in the sun."

But that could start to change, he said, "because people fear cancer in ways that they don't fear other diseases."

In that case, we might soon see the rise of extremely graphic PSAs featuring people whose cancer could be attributed to their junk-food habits.