Lifetime exercise may cut breast cancer death risk

NEW YORK (Reuters Health) - Women who participate in recreational exercise and sports over their lifetime may be lowering their risk of death from breast cancer and breast cancer recurrence.

Among 1,231 women with breast cancer who were followed for a minimum of 8.3 years, those who obtained about 4 hours or more of weekly moderate-intensity recreational activity over their lifetime had a 44 percent lower risk of death from breast cancer, report Dr. Christine Friedenreich and colleagues.

Risk for recurrence, progression, or new primary breast cancer was likewise reduced by 34 percent among women reporting similar levels of recreational physical activity, note Friendenreich, of Alberta Health Services-Alberta Cancer Board in Calgary, Canada, and colleagues.

These findings suggest "being physically active before a breast cancer diagnosis can improve survival after breast cancer," Friendenreich told Reuters Health.

However, occupational activity and physical household work such as gardening, housework, and do-it-yourself home repair did not confer benefits similar to those from lifetime exercise and sports activities, the investigators report in the International Journal of Cancer.

Friendenreich's team compared the lifetime physical activity reports of 1,231 women, who were 56 years old on average when diagnosed with breast cancer, with their outcomes. Over a minimum of 8.3 years of follow up, 341 women died (223 from breast cancer) and 327 had a recurrence, progressions, or new primary breast cancer diagnoses.

Compared with the least active women (less than 1.4 hours per week of recreational activity), those who engaged in more than 3.9 hours per week of moderate intensity recreational activity had 34 percent decreased risk for the combined outcomes, and 44 percent reduced risk for death from breast cancer.

These effects remained apparent after allowing for other factors potentially associated with survival such as body mass, tumor stage, and age.

Vigorous-intensity recreational activity lowered the risk of breast cancer mortality, but did not appear to reduce the risk of other outcomes.

Friendenreich notes her team continues examinations of "exactly what type and dose of activity is related to improved survival after cancer." Ultimately they hope this research leads to development of clear exercise guidelines for cancer patients.