Increase Your Activity to Decrease Cancer Risk
Scientists have long known that regular physical activity reduces the risk of colon, breast, and endometrial cancer. But a new study* out of the National Cancer Institute and the American Cancer Society has revealed that exercise has bigger muscle in battling The Big C than anyone had previously even hoped to imagine.
In a study* that pooled 11 years of data on nearly 1.5 million people ages 19 to 98, investigators found that regular physical activity was linked to a lower risk of those three cancers—plus an astonishing 10 others. The greatest reductions in risk were for esophageal adenocarcinoma, liver cancer, cancer of the gastric cardia, kidney cancer, and myeloid leukemia, but myeloma and cancers of the head and neck, rectum, and bladder also showed reduced risks that were significant, just not as strong. Plus, risk was reduced for lung cancer—but only for current and former smokers; the scientists aren’t yet sure why.
“Prior studies had examined physical activity in relation to risk of many of the cancers we examined, and results were suggestive but not definitive,” says cancer epidemiologist and lead study author Steven Moore, Ph.D., an Earl Stadtman Investigator in the Metabolic Epidemiology Branch of the National Cancer Institute’s division of Cancer Epidemiology and Genetics. “We thought we’d be able to confirm some of the associations in our own study. But even we were surprised to confirm as many of the associations as we did.”
In Moore’s research, physical activity was defined as moderate-to-vigorous-intensity exercise done at one’s own discretion, often to improve or maintain fitness or health—exactly like your time at Curves. And the median level of activity in the study was about 150 minutes of moderate-intensity per week, or, about the current recommended minimum level of physical activity in the US.
“Ours was an observational study,” cautions Moore, “so we can draw no conclusions about cause and effect from it.” Still, the scientists speculate that cancer growth could be initiated or abetted by three metabolic pathways that are also affected by exercise: sex steroids (estrogens and androgens); insulin and insulin-like growth factors; and proteins involved with both insulin metabolism and with inflammation.
What they do know definitively: Their results applied to everyone. In other words, they found no difference in the effect on cancer risk between men and women. No significant difference in people who were slim and those who were overweight or even obese. And no difference in those who had a history of smoking and those who did not.
“Physical inactivity has become a major public health concern, across all populations,” says Moore, who points out that cancer, of course, is no boon to the public health, either. “Our study results strongly suggest that exercise should be a key component of population-wide, every-person-out-there cancer prevention and control efforts.”
“While our study does not specifically address physical activity in people after a cancer diagnosis,” he says, “it does seem likely that the benefits of regular physical activity would be similar for that group as for others.”
Ready, set, move!
*Moore SC, et al. Leisure-time physical activity and risk of 26 types of cancer in 1.44 million adults. JAMA Internal Medicine. May 16, 2016. DOI:10.1001/jamainternmed.2016.1548.
