Recreational physical activity, anthropometric factors, and risk of ductal carcinoma in situ of the breast in a cohort of postmenopausal women

Objective: To assess the association of recreational physical activity and anthropometric factors in relation to risk of ductal carcinoma in situ (DCIS) of the breast. Methods: The association was examined in a cohort of 58,055 postmenopausal women participating in the Women's Health Initiative (WHI) clinical trials, among whom 450 cases of DCIS were ascertained after a median follow-up of 8.0 years. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). Results: After adjustment for covariates, the hazard ratio for DCIS among women with ≥20 metabolic equivalent task-hours per week (MET-h/week) of total recreational physical activity compared to women who did not engage in any recreational physical activity (0 MET-h/week) was 0.97 (95% CI 0.70-1.34). Neither body mass index nor waist circumference was associated with risk. In addition, physical activity and anthropometric factors were not associated with risk of either high-grade or low-/moderate-grade DCIS. Conclusions: Recreational physical activity and anthropometric factors showed no association with risk of DCIS in postmenopausal women in the WHI clinical trial.