A new study, published online in the International Journal of Cancer on February 17, 2006 tries to throw some light on the link between colon cancer and the level of physical activity in women. The prospective cohort study of 31,783 American women has found no such link.

Experts felt that since exercise is known to alter the production of prostaglandins and insulin besides increasing the gastrointestinal transit time, it might also play a constructive role in reducing the incidence of colon cancer. A team of researchers led by Brook A. Calton, M.H.S. formerly at the National Cancer Institute and now at the University of California-San Francisco, looked into the relation if any between colon cancer and the level of physical activity in women.

They collected information about the level of physical activity and the incidence of colon cancer in the 31,783 women from the Breast Cancer Detection Demonstration Project Follow-up Study. They found 243 cases of colon cancer between 1989 to 1998. However, they were unable to find any link between exercise and 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 incidence of colon cancer," the authors said. They acknowledge that there might have been several imperfections in the analysis, but this could only confer a marginal benefit if any, "Our results do not support the hypothesis that physical activity confers significant protection against the overall development of colon cancer in women.

Our findings point towards the need for conducting further research, particularly among women, that uses well-formulated, accurate measures of physical activity and distinguishes between different types of physical activity (i.e. recreational, occupational, and household activity) in relation to colon cancer risk," they conclude.