Colon cancer risk in women does not seem to be reduced by physical activity.

“Physical activity has frequently been reported to decrease the risk of colon cancer in men, but data on the relation of physical activity to colon cancer risk in women have generally been less consistent. To further investigate the relationship of physical activity with colon cancer risk in women, we studied a cohort of 31,783 U.S. women participating in the Breast Cancer Detection Demonstration Project Follow-up Study,” reported researchers at the U.S. National Cancer Institute.

B.A. Calton and colleagues explained, “Information on daily physical activity over the past year was ascertained using a self-administered questionnaire at study baseline. The Cox proportional hazards model was used to estimate relative risks (RRs) relating physical activity to the risk of incident colon cancer.”

“During 270,325 person-years of follow-up, 243 colon cancer cases were identified,” they reported. “No association was observed between physical activity and the subsequent risk of colon cancer. The multivariable RRs of colon cancer across increasing quintiles of total physical activity were 1.0, 1.45, 1.16, 1.27 and 1.15 (95% CI: 0.76, 1.75; ptrend =0.77). The multivariable RRs comparing women at the extremes of moderate and vigorous physical activity, respectively, were 1.07 (95% CI: 0.70, 1.62) and 1.10 (95% CI: 0.78, 1.55).”

“The relationship between physical activity and colon cancer risk did not vary by anatomic subsite or across subgroups defined by age, body mass, dietary fiber intake, menopausal status, menopausal hormone use or aspirin use,” the authors noted.

They concluded, “The results of this large prospective cohort study among women do not support the hypothesis that physical activity is related to a lower incidence of colon cancer.”

Calton and colleagues published their study in the International Journal of Cancer (Physical activity and the risk of colon cancer among women: A prospective cohort study (United States). Int J Cancer, 2006;119(2):385-391).

For more information, contact B.A. Calton, Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 6120 Executive Boulevard, EPS 3028, Rockville, MD 20852, USA; E-mail: .(JavaScript must be enabled to view this email address).

Publisher contact information for the International Journal of Cancer is: Wiley-Liss, Division of John Wiley & Sons Inc., 111 River Street, Hoboken, NJ 07030, USA.