Brisk walking for just an hour or two weekly can help older women reduce their risk of breast cancer by nearly 20%, even if they have used hormone pills for symptoms of menopause, according to a new study in the September 10 edition of the Journal of the American Medical Association. The findings are based on data from a landmark study that linked hormone use to breast cancer, heart attacks, and strokes. They suggest that exercise may help counteract--but not cancel out--the increased risk of breast cancer faced by longtime hormone users, said lead researcher Anne McTiernan of the Fred Hutchinson Cancer Research Center in Seattle. "We thought it important to determine if moderate-intensity physical activities, such as walking, biking outdoors, or easy swimming, when initiated later in life, can reduce the risk of breast cancer since these types of activities are achievable for most women," McTiernan said.
The researchers analyzed data on 74,171 women ages 50 to 79 who participated in the government's Women's Health Initiative study from 1993 to 1998. Women who said they engaged in about 1.25 to 2.5 hours of moderate exercise weekly had an 18% lower risk of breast cancer than inactive women. A separate study in JAMA found that moderate exercise combined with dieting is about as effective as intense exercise in helping younger women lose weight and improve cardiovascular fitness.
The Women's Health Initiative study made headlines last summer when it was halted after finding that the risks of hormone pills containing estrogen and progestin outweighed the benefits for postmenopausal women.