Sedentary time and postmenopausal breast cancer incidence. 

 -  2017 
<br/><br/> CONCLUSIONS: Results from this study do not support an association between sedentary time and breast cancer incidence.  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.  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.  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. 
<br/><br/><br/>English 
<br/><br/><label>ISSN: </label>0957-5243 
<br/><br/><label>Subjects--Topical Terms: </label><br/>*Breast Neoplasms/ep [Epidemiology]<br/>*Postmenopause<br/>*Sedentary Lifestyle<br/>Aged<br/>Breast Neoplasms/eh [Ethnology]<br/>Continental Population Groups<br/>Ethnic Groups<br/>Exercise<br/>Female<br/>Humans<br/>Incidence<br/>Middle Aged<br/>Proportional Hazards Models<br/>Prospective Studies<br/>Surveys and Questionnaires
<br/><br/><label>Subjects--Geographic Terms: </label><br/>MedStar Health Research Institute
<br/><br/><label>Index Terms--Function: </label><br/>Journal Article