Abstract

Relatively consistent findings about the relationships between body size and shape and breast cancer risk have been emerging in recent years. Adult height is predictive of breast cancer risk, even in populations with no evidence of energy or nutrient deficiency. A complex relationship with adiposity has been observed. The dominant pattern is increasing risk with increasing adiposity except in younger, premenopausal women from countries with high breast cancer rates, in whom an inverse association is noted. When adult weight is evaluated as a dynamic measurement rather than a constant one, excess weight in the years preceding breast cancer diagnosis seems especially critical, consistent with the substantial evidence that adiposity at the time of breast cancer diagnosis is associated with an increased probability of recurrence and a decreased survival time. Adult weight gain has consistently predicted increased risk of breast cancer in older, postmenopausal women, even in some studies in which adult adiposity was only weakly associated with risk. In several studies, women with increased abdominal fat deposition, or central adiposity, also had an elevated risk of postmenopausal, though not necessarily premenopausal, breast cancer, independent of their adult adiposity. These patterns suggest that lifestyles leading to a positive energy balance are involved in the etiology of this disease and that energy intake and physical activity may be especially influential. The hormonal and metabolic mechanisms that account for these relationships between body size and shape and breast cancer risk are not adequately understood and merit further study.