Exercise linked to reduced risk of several cancers

Physical activity has been associated with lower risk of heart disease and all cause mortality, but its association with risk of cancer is not well understood.

Moore et al research published in JAMA Internal Medicine, suggests that exercise is a powerful cancer-preventive and found that physical activity drove down the rates of a broad array of cancers even among smokers, former smokers, the overweight and obese.

Researchers collected data from 12 prospective studies from the United States and Europe and analyzed associations between self-reported physical activities with the incidence of 26 types of cancer in the study period, which lasted 11 years between 1987 and 2004.

A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High versus low levels of physical activity were associated with lower risk of 13 cancers: esophageal adenocarcinoma, liver, lung, kidney, gastric, endometrial, myeloid leukemia, myeloma, colon, head and neck, rectal, bladder, and breast. The data indicated that a higher level of activity was tied to a 7 percent lower risk of developing any type of cancer. Individuals who were very active had a 20% lower risk of cancers of the esophagus, lung, kidney, stomach, endometrium compared with people who were less active.  The reduction was slightly lower for colon, bladder, and breast cancers.

Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. Leisure-time physical activity was associated with higher risks of malignant melanoma and prostate cancer.  Associations were generally similar between overweight/obese and normal-weight individuals. Smoking status modified the association for lung cancer but not other smoking-related cancers.

Health care professionals should emphasize that physical activity was associated with lower risks of many cancer types and most of these associations were evident regardless of body size or smoking history.