Data on cancer relative to physical activity have been inconsistent and difficult to interpret because cancer represents not one disease, but many distinct, site-specific diseases. To further complicate the situation, risk factors are specific to each disease. Nevertheless, over the past decade, increasing evidence indicates that physical activity is associated with decreased overall cancer mortality and decreased incidence of specific types of cancers (Sternfeld, 1992; Lee, 1995). The cancer site most frequently studied in relation to physical activity is colon cancer, and findings overwhelmingly support an inverse relationship. The two most likely potential mechanisms by which physical activity may be protective of.
