Physical activity, diet, adiposity and female breast cancer prognosis: a review of the epidemiologic literature

Given the increasing numbers of long-term survivors of breast cancer, research specific to prevention of recurrence, new breast cancer events, and mortality is of considerable public health importance. The objective of this report is to present a review of the published epidemiologic research on lifestyle and breast cancer outcomes among women with a history of breast cancer. This review focused on physical activity, diet, and adiposity; and the primary outcomes were additional breast cancer events and mortality. The most consistent finding from observational studies was that adiposity was associated with a 30% increased risk of mortality. Although the observational data were not as consistent (or abundant), physical activity appeared to be associated with a 30% decreased risk of mortality. These data do not indicate that alcoholic drinks are a risk factor. Based only on the observational studies, total dietary fat appeared to be a risk factor, fiber was protective, and information on micronutrients and specific foods was sparse. However, the null results of 2 dietary intervention trials in survivors suggests that lowering fat intake or increasing consumption of fruits, vegetables, and fiber will not lead to improved prognosis in breast cancer survivors. Given that a high proportion of breast cancer patients appear to be both sedentary and obese/overweight, clinical trials are needed to investigate whether the combination of increased physical activity and reduced adiposity can improve breast cancer prognosis.