Staying active increases the chances of survival in women suffering from breast cancer, regardless of the physical activity before the diagnosis. Previous reports suggest that physical activity may stave off breast cancer, but the beneficial effects after the disease has developed were unclear. Researchers from the Harvard Medical School in Boston investigated whether physical activity lowers the risk of dying from breast cancer. They analyzed the data from 2987 women who were enrolled in the Nurses' Health Study and diagnosed with breast cancer between 1984 and 1998. The subjects were followed until June 2002 or until they died, whichever came first. The risk of death from breast cancer fell as physical activity increased. Women who engaged in more than 3 MET-hours (metabolic equivalent task) of activity per week, were able to reduce their risk of breast cancer mortality by 20% - 50%. Three MET - hours is equal to walking at an average pace (2 to 3 m.p.h.) for 1 hour. Nine or more MET-hours per week of physical activity was associated with a 6 percent reduced risk of death from breast cancer over a 10-year period, compared with less than 3 MET-hours per week. The findings suggest that women with breast cancer who exercise at moderate intensity for 30 or more minutes per day for 5 or more days per week may survive longer.
Journal of the American Medical Association,
May 2005