PHYSICAL-ACTIVITY AND RISK OF BREAST-CANCER

The association between recreational physical activity and breast canc er risk was examined in a population-based case-control study in Adela ide, Australia between 1982 and 1984, There were 451 incident, histolo gically confirmed cases of breast cancer, identified through the South Australian Central Cancer Registry, which were each age-matched to on e control selected at random from the electoral register. These women, aged 20-74 years at diagnosis, reported their level of weekly recreat ional physical activity in a self-administered questionnaire, The ques tionnaire reports of light, moderate and vigorous physical activity we re converted into total kilocalories per week of energy expenditure, A decrease in risk of breast cancer was found with increasing levels of total recreational physical activity (P (trend) = 0.09), The adjusted odds ratio for those women who expended more than 4,000 kcal/week was 0.73 (95% confidence interval (CI) 0.51-1.05) compared with women who undertook no physical activity, The reduction in risk with recreation al physical activity was most evident for women who undertook any vigo rous activity, These results provide some support for the hypothesis t hat physical activity may decrease the risk of developing breast cance r.