Occupational physical activity and the risk of breast cancer

The association between occupational and the risk of breast cancer was analyzed using data from a case-control study of 257 women with breast cancer and 565 control women. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for occupations having light and medium activity compared with sedentary ones. After adjusted for potential confounders, women in sedentary occupations had a 29% higher risk, compared to those with the physically medium demanding jobs. For women at age greater than or equal to55 years higher occupational physical levels were associated with 53-60% reduction in the risk. There was a significant decreasing trend in the ORs from sedentary to medium work (P = 0.001); while no association emerged in younger women. These findings demonstrate that the protective effect of higher levels activity in occupations on breast cancer appears to be confined to older women. (C) 2003 International Society for Preventive Oncology. Published by Elsevier Science Ltd. All rights reserved.