ORIGINAL CONTRIBUTION Physical Activity and Survival After Breast Cancer Diagnosis

PHYSICAL ACTIVITY AFTER A breast cancer diagnosis has been strongly linked to improved quality of life. There is reason to believe that physical activity might extend survival in women with breast cancer. Physical activity also has been linked to a lower risk of breast cancer. An expert panel of the International Agency for Research on Cancer of the World Health Organization estimated a 20% to 40% decrease in the risk of developing breast cancer among the most physically active women, regardless of menopausal status, type, or intensity of activity. Physical activity has been linked to lower levels of circulating ovarian hormones, which may explain the relationship between physical activity and breast cancer. Lower estrogen levels among physically active women with breast cancer could potentially improve survival, although few data exist to support this hypothesis. Lack of physical activity has been shown to be related to weight gain during breast cancer survival. 0 Weight gain after a breast cancer diagnosis is a common adverse effect of treatment. This is important because both being overweight at the time of breast cancer diagnosis and weight gain after diagnosis are linked to poorer survival in many studies. Lack of physical activity is believed to be as important a factor as changes in food intake in the ongoing obesity epidemic. Few have studied associations between physical activity and survival and no studies have assessed physical activity level after diagnosis. Rohan et al found no association between physical activity before diagnosis and survival in a population-based prospective study of 412 women with breast cancer. We hypothesized that higher levels of physical activity after a breast cancer diagnosis would be associated with longer survival.