Increased physical activity decreases risk of colorectal cancer

Dec 15 2009

Increased physical activity appears to be associated with a lower risk of cancer-specific and overall death in men with a history of colorectal cancer that has not spread to other parts of the body, according to a report in the December 14/28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

Approximately 150,000 Americans are newly diagnosed with colon cancer each year and almost 50,000 die of the disease annually, according to background information in the article. Although physical activity is known to help prevent the development of colon cancer, few studies have examined its effect on colon cancer survivors.

Jeffrey A. Meyerhardt, M.D., M.P.H., of Dana-Farber Cancer Institute, Boston, and colleagues studied the association of physical activity with colon cancer-specific and overall death in a group of 668 men with a history of stage I, stage II and stage III nonmetastatic (cancer that has not spread) colon cancer. Participants received follow-up questionnaires every two years to report new cancer and disease diagnoses as well as any leisure-time physical activity including walking, bicycling and other aerobic exercises; yoga, stretching and other lower-intensity exercise; or other vigorous activities. Each physical activity was assigned a metabolic equivalent task (MET) score. Activities that required more energy were assigned higher MET scores.

There were 258 deaths in the group of study participants, of which 88 were due to colon cancer. "Men who were physically active after diagnosis of nonmetastatic colorectal cancer experienced a significantly decreased risk of colorectal cancer-specific death, as well as death from any cause," the authors write. "Men who engaged in more than 27 MET hours per week had more than 50 percent lower risk of colorectal cancer-specific mortality compared with inactive men. This association was consistently detected regardless of age, disease stage, body mass index, diagnosis year, tumor location and prediagnosis physical activity."

"These results provide further support that physical activity after colorectal cancer diagnosis may lower the risk of death from that disease," the authors conclude. "A randomized study among high-risk stage II and stage III colon cancer survivors that will compare the use of general education materials with a program that includes supervised physical activity sessions and behavioral support delivered over three years will soon open; the primary end point is disease-free survival. The findings from the present study further support that effort."
(Arch Intern Med. 2009;169[22]:2102-2108. Available pre-embargo to the media at www.jamamedia.org.)