ASPO Abstracts
Longitudinal changes in volumetric breast density in healthy women across the menopausal transition.
Category: Lifestyles Behavior, Energy Balance & Chemoprevention, Molecular Epidemiology & Environment
Conference Year: 2018
Abstract Body:
Purpose: Many women experience declines in mammographic breast density during menopause, with some women experiencing greater reductions than others. We assessed changes in volumetric breast density across the menopausal transition and factors that influence these changes. Methods: Women without a history of breast cancer, mastectomy or implants who had full field digital mammograms during both pre- and postmenopausal periods, at least 2 years apart, were sampled from 4 facilities within the San Francisco Mammography Registry from 2007 to 2013 Volumetric percent density (VPD) and dense volume (DV) were assessed using VolparaTM on all available digital mammograms across the time period. Risk factors (body mass index (BMI), alcohol use, parity, age at first birth, race, hormone therapy and family history) were self-reported at each mammogram. Annualized change in volumetric density measures from pre- to post- menopause were estimated using linear mixed models, adjusting for age, density and BMI at baseline, and BMI change from baseline. Multiplicative interactions were evaluated between baseline risk factors and time to determine if these covariates modified the annualized changes. Results: Among the 2587 women who met inclusion criteria, 1767 had two mammograms, 655 had three, and 165 had four. Mean age was 50.5 (range: 35-54) years at premenopausal mammogram, and median time between earliest and latest mammograms was 3.0 (IQR: 2.0, 3.3) years. Women experienced an annualized decrease in both VPD (-0.6%) and DV (-2.2 cm3) over the time period. Annualized declines were greater among women with a baseline VPD above a median VPD of 11.9% vs. below (VPD: -1.0% vs. -0.2%, p<0.0001) and baseline DV above a median DV of 58 cm3 vs. below (DV: -3.4 cm3 vs. -1.0 cm3, p<0.0001). Women with baseline BMI <25 kg/m2 had greater declines in VPD than those with BMI30 kg/m2 (-0.8% vs. -0.1%, p<0.001), though changes in DV by BMI were not significant (-2.0 cm3 vs. -2.5 cm3, p=0.46). Conclusion: High baseline breast density and BMI <25 kg/m2 were predictors of greater reductions in volumetric density across the menopausal transition. Future research should examine if volumetric density declines across the menopausal transition are associated with decreased breast cancer risk.
Keywords: volumetric breast density, menopause, obesity