Because exercise has been shown to accelerate gastrointestinal transit time, upregulate immune function, and alter the production of prostaglandins and insulin, experts have theorized that it might also inhibit colon cancer. Over forty epidemiologic studies have examined the association with varying results. Many observed a reduction in colon cancer risk for people reporting high levels of activity, compared to those who did not. Several studies have shown a stronger inverse relationship for men, compared to women. Other studies have found no association at all for women.
To better understand the relationship between physical activity and colon cancer risk in women, researchers led by Brook A. Calton, M.H.S. formerly at the National Cancer Institute and now at the University of California-San Francisco, conducted a prospective study of a large cohort of post-menopausal women in the United States. Using the Breast Cancer Detection Demonstration Project Follow-up Study, they collected information about physical activity and colon cancer cases for 31,783 women. There were 243 cases of colon cancer during the ten-year study period from 1989 to 1998.
The researchers analyzed reported physical activity for all women in the cohort using a Cox proportional hazards regression, and observed no association between physical activity and the subsequent risk of colon cancer. "The results of this large prospective cohort study among women do not support the hypothesis that physical activity is related to a lower
Contact: David Greenberg
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