Breast cancer

Women who had a family history of breast cancer reduced their risk by one-fourth by doing 20 minutes of moderate or vigorous physical activity at least five times a week, along with maintaining a healthy lifestyle in other ways, according to a study published in October in the journal Breast Cancer Research.

Even ex-couch potatoes can reap immediate anti-cancer rewards: postmenopausal women who gave up their sedentary ways and engaged in a moderate- to vigorous- intensity exercise program showed changes in hormone and protein levels consistent with a reduced risk of breast cancer, according to a study published online in February in the Journal of Clinical Oncology.

Some findings suggest that starting an exercise program during adolescence may delay the onset of breast cancer for women who may carry a mutation in their BRCA genes (which are associated with an increased risk for the disease), but it doesn't prevent the disease from developing, Furth said.