How Physical Activity Helps Prevent Cancer
Previous studies provide evidence that exercise can help prevent a variety of cancers; data suggests that the link between exercise and colon cancer may be particularly strong.
A study involving 63 men and women (42-78 years of age) with a history of colonic polyps (a potential precursor to colon cancer) investigated the potential influence of leisure-time physical activity and low body mass index (BMI) on levels of prostaglandin E2 in rectal mucosa.
High prostaglandin levels have been shown to be associated with the development of colon cancer.
Self-administered questionnaires assessed leisure-time physical activity per week, and levels of prostaglandin E2 were measured by examining rectal biopsy tissue samples taken eight weeks apart.
Prostaglandin levels increased with higher weight, higher BMI, and lower levels of leisure-time physical activity. An increase in BMI from 24.2 to 28.8 kg/m2 resulted in a 27% increase in prostaglandin levels, whereas an increase in physical activity from 5.2 to 27.7 MET-hours per week (one MET-hour being roughly equivalent to an oxygen uptake of 3.5ml/kg of body weight per minute) decreased prostaglandin levels by 28%.
Increasing physical activity and reducing body mass index may decrease the risk of colon cancer. These findings add support to previous evidence suggesting the protective value of physical activity against cancer and other chronic diseases.
Martinez ME, Heddens D, Earnest DL, et al. Physical activity, body mass index, and prostaglandin E2 levels in rectal mucosa. Journal of the National Cancer Institute
, June 2, 1999:91(11), pp950-53.