Physical Activity Cuts Polyp Risk

The reason that regular exercise reduces risk of getting colon cancer may be because it also reduces polyps.

An analysis of 20 studies of adenomas — precancerous polyps that raise risk for colon cancer –  found that regular physical exercise reduced polyp risk by 16 percent.  More important, exercise cut back the number of the most dangerous large and advanced polyps by almost a third.

It didn’t matter whether exercise was recreational or job-related. Jogging, biking, and swimming helped, but so did walking  on the job, lifting, and digging.

The analyzed studies focused on colon cancer, which exercise has been shown to prevent.  There hasn’t been a similar exercise reduction in rectal cancer.

Lead study author Kathleen Y. Wolin, Sc.D., assistant professor of surgery at Washington University School of Medicine said,

What’s really compelling is that we see the association between exercise and lower colon cancer risk regardless of how physical activity was measured in the studies.,That indicates that this is a robust association and gives all the more evidence that physical activity is truly protective against colon cancer.

A previous meta-analysis of 52 studies by Dr. Wolin found that exercise reduced colon cancer by about 25 percent, with similar effects in both men and women.

Several ways that exercise might affect polyps and the development of cancer include reducing inflammation, enhancing immune function, increasing vitamin D levels, and reducing insulin levels and insulin resistance.

Dr. Wolin and her team concluded,

This study confirms previous reports of a significant inverse association of physical activity and colon adenoma, and suggests that physical activity can have an important role in colon cancer prevention.

SOURCE: Wolin et al., British Journal of Cancer,Volume 104, pages 882-885, March 1, 2011.