Data from 90,509 women participating in the E3N cohort study suggest that regular, vigorous physical activity may be associated with a lower risk of breast cancer. The findings were published in Cancer Epidemiology, Biomarkers & Prevention (2006; 15(1):57–64). Women aged 40 to 65 at baseline were followed for 12 years, during which time 3,424 cases of breast cancer were diagnosed. Physical activity frequency and intensity were assessed, and an inverse relationship was observed between activity level and breast cancer incidence. Women who reported more than five hours per week of vigorous recreational activity had a relative risk of 0.62 compared with women who reported no recreational physical activity.