Regular Exercise Lowers Breast Cancer Risk

Obesity has been associated with increased risk for postmenopausal breast cancer, with a number of published studies assessing with body mass index (BMI) which does not distinguish between fat and lean mass.  Tim Key, from the Cancer Epidemiology Unit at Oxford University (United Kingdom), and colleagues assessed data collected in the UKL Biobank study, involving 125,788 postmenopausal women followed for five years, during which time 1,122 cases of invasive breast cancers occurred.  During the study, researchers tracked body fat percentage while subjects self-reported physical activity and other lifestyle activities.  The data revealed that vigorous physical activity reduced breast cancer risk by one-fifth, as compared to sedentary counterparts.  Also, women with the most body fat were 55% more likely to develop breast cancer, as compared to leaner subjects.  The study authors conclude that: “Our results show that women with a high percentage of body fat have a high risk for breast cancer, and suggest that vigorous physical activity protects against breast cancer, beyond its role in decreasing body fat percentage.”