Sedentary time and postmenopausal breast cancer incidence.

ABSTRACT: PURPOSE:The objective of this study was to evaluate the prospective association between sedentary time and postmenopausal breast cancer incidence, and whether associations differ by race/ethnicity, physical activity levels, and body measurements. METHODS:The Women's Health Initiative Observational Study is a prospective cohort among women ages 50-79 years at baseline (1994-1998) (analytic cohort?=?70,233). Baseline questionnaire data were used to estimate time spent sitting and total sedentary time. Associations between time spent sitting and invasive breast cancer incidence overall (n?=?4,115 cases through September 2015), and by hormone receptor subtypes, were investigated using Cox proportional hazards regression. Analyses were replicated stratified by race/ethnicity, body measurements, and physical activity. RESULTS:Among women in this study, 34.5% reported???5 h/day sitting, 40.9% reported 6-9 h/day and 24.7% reported???10 h/day. Time spent sitting (??10 vs. ?5 h/day adjusted HR?=?1.00, 95% CI 0.92-1.09) was not associated with breast cancer incidence, regardless of hormone receptor subtype. Associations did not differ by race/ethnicity, physical activity, or body measurements. CONCLUSIONS:Results from this study do not support an association between sedentary time and breast cancer incidence.

SUBMITTER: Nomura SJO 

PROVIDER: S-EPMC5687985 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature