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Breast Cancer Population Attributable Risk Proportions Associated with Body Mass Index and Breast Density by Race/Ethnicity and Menopausal Status



Overweight/obesity and dense breasts are strong breast cancer risk factors whose prevalences vary by race/ethnicity. The breast cancer population attributable risk proportions (PARPs) explained by these factors across racial/ethnic groups are unknown.


We analyzed data collected from 3,786,802 mammography examinations (1,071,653 women) in the Breast Cancer Surveillance Consortium, associated with 21,253 invasive breast cancers during a median of 5.2 years follow-up. Hazard ratios (HRs) for body mass index (BMI) and breast density, adjusted for age and registry were estimated using separate Cox regression models by race/ethnicity (white, black, Hispanic/Latina, Asian) and menopausal status. HRs were combined with observed risk-factor proportions to calculate PARPs for shifting overweight/obese to normal BMI and shifting heterogeneously/extremely dense to scattered fibroglandular densities.


The prevalences and HRs for overweight/obesity and heterogeneously/extremely dense breasts varied across races/ethnicities and menopausal status. BMI PARPs were larger for post- vs. premenopausal women (12.0-28.3% vs. 1.0-9.9%) and nearly double among postmenopausal black women (28.3%) than other races/ethnicities (12.0-15.4%). Breast density PARPs were larger for pre- vs. postmenopausal women (23.9-35.0% vs. 13.0-16.7%) and lower among premenopausal black women (23.9%) than other races/ethnicities (30.4-35.0%). Postmenopausal density PARPs were similar across races/ethnicities (13.0-16.7%).


Overweight/obesity and dense breasts account for large proportions of breast cancers in white, black, Hispanic, and Asian women despite large differences in risk-factor distributions.

To read more, see the following article on the PubMed website: PMID: 32727722