Evidence Mounts That Diet, Exercise Help Survivors Cut Cancer Risk

Eat right and exercise is about as basic as medical advice gets.

Follow it, and you’ll benefit from better overall fitness, improved quality of life, and a reduced risk for chronic conditions, such as heart disease and diabetes.

The American Cancer Society now says the evidence has piled up that diet and exercise can help cancer survivors manage, beat, and stay free of their disease, too.

“There’s just been an explosion of research in this area that gives us the confidence that these things matter,” Colleen Doyle, director of nutrition and physical activity for ACS, tells Shots.

Doyle is a co-author of the Nutrition and Physical Activity Guidelines for Cancer Survivors. Published this morning online by CA: A Cancer Journal for Clinicians, the guidelines are based on the results of more than 100 studies released since 2006, the last time ACS weighed in on the issue.

Those studies “really spell out the benefits of weight control, of physical activity, and of healthy diet in terms of recurrence of cancer and surviving cancer,” Doyle says.

They key recommendations are:

  • Get regular aerobic and resistance exercise;
  • Eat a diet low in red meat and saturated fats, and high in fruits, vegetables and whole grains;
  • Use other weight-management strategies, such as portion control, to reach and maintain a healthy weight.

It’s not rocket science. After all, these are the same things healthy people are told to do to maintain overall fitness. But for cancer survivors, the stakes are even higher: in addition to the risk of recurrence, they also tend to be at increased risk of developing a second primary cancer.

So one might think they would be more inclined to take care of their overall health. But, in fact, Doyle says, “cancer survivors are no more likely to meet recommendations” than anybody else. She says the strength of the current evidence should be “a call to action” for the growing millions of cancer survivors.

There are some caveats, of course. Different types of cancer, and different types of treatment, can change a patient’s nutritional needs or make it more difficult to exercise. The guidelines acknowledge that it can be hard to make substantial changes in diet and lifestyle while undergoing the turmoil of cancer treatment, but recommend starting as soon as possible.

Nutritional supplements are one area where the new guidelines may surprise cancer survivors, who report using supplements at higher rates than the general population. Basically, the ACS says, don’t use them. Doyle says there is almost no evidence that supplements help cancer survivors, and there is mounting evidence that some supplements can actually promote cancer growth or interfere with treatment.

Antioxidants, for instance, which repair cell damage, are thought to be helpful when absorbed in normal amounts through food. But some research suggests that the megadoses of many antioxidant supplements might counteract the effects of chemo- or radiation therapy. There’s also some evidence that nutrients like folate, calcium, and beta-carotene may interfere with treatment or promote the growth of certain cancers.

In the absence of clear scientific answers, ACS recommends erring on the side of caution. So unless a doctor recommends them to address a specific dietary deficiency, supplements should be avoided.

Instead, Doyle says, survivors should try to eat a more nutritious diet in the first place. “Bottom line, consider what you’re eating,” she says. “Get your nutrients, as best you can, from food.”

For a summary of the new guidelines, or to view the full report, visit the website of CA: A Cancer Journal for Clinicians.

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.