CALGARY, CANADA. Canadian researchers have released the results of a major study evaluating the effect of lifetime physical activity on breast cancer risk. The study included 1233 women with breast cancer and 1237 controls and was conducted in Alberta during the period 1995-97. All study participants underwent comprehensive interviews to determine their lifetime physical activity level, diet, smoking status, alcohol consumption, reproductive history, and body measurements. The researchers found no correlation between lifetime physical activity level and breast cancer risk in premenopausal women. Among postmenopausal women, however, they observed a clear risk reduction with increased household and occupational physical activity, but not with increased recreational physical activity. Women who had been most active during their lifetime (household and occupational) had an almost 40 per cent lower risk of breast cancer than did less active women. Active women who did not consume alcohol had a 61 per cent lower risk and active women who had not had any children (nulliparous) had a 78 per cent risk reduction. The researchers conclude that a high level of physical activity over a lifetime reduces the risk of breast cancer in postmenopausal women.
Friedenreich, C.M., et al. Case-control study of lifetime physical activity and breast cancer risk. American Journal of Epidemiology, Vol. 154, August 15, 2001, pp. 336-47