Energy balance, body size, and cancer.

Increased energy intake and physical inactivity have been shown to heighten the risk of breast, large bowel, and other cancers. Large body size and fatness, as measured by adult stature, body weight and body mass indices, are positively related to a variety of cancers, including breast, colorectum, prostate, endometrium, kidney, and ovary, as well as to total cancer incidence or mortality in many investigations, although conflicting reports exist. Adult weight gain has also been specifically implicated in a few etiologic studies of breast and large bowel cancer. Furthermore, increased birthweight and childhood stature have been linked to increased risk of leukemia, lymphoma, osteogenic sarcoma, and central nervous system malignancies between infancy and young adulthood. Greater body weight also adversely affects breast cancer survival. These findings are complementary and support a role for positive energy balance in promoting human carcinogenesis. Potential mechanisms are discussed.