Abstract 4248: Adiposity, change in adiposity during adulthood and mammographic density in premenopausal women

Abstract Background: Body mass index (BMI) is inversely associated with mammographic density among postmenopausal women, but few studies have evaluated this in premenopausal women. Further, there is limited data on the associations of weight change during adulthood with mammographic density. To address these, we investigated the associations of current adiposity measures, BMI at ages 18, 30, and changes in BMI at these age periods with volumetric mammographic density measures in 314 premenopausal women who underwent screening mammogram at the Breast Health Center, Washington University in St. Louis, MO. Methods: Study participants completed a questionnaire with information on breast cancer risk factors. Weight at ages 18 and 30 were self-reported. Current weight, height, waist, and body fat percent (%), were assessed by trained research personnel. BMIs were calculated as weight at each age/current height squared (kg/m2). We calculated weight change from; (i) age 18 to 30, (ii) age 18 to current age, (iii) age 30 to current age. Volpara was used to determine volumetric mammographic density measures. We investigated age-adjusted correlations between adiposity measures and mammographic density measures using Pearson correlation coefficients. We used multivariable linear regression models (adjusted for age, age at menarche, parity, age at each birth, family history of breast cancer, race, and education) to evaluate the associations of adiposity measures with mammographic density measures. Results: All adiposity and weight change measures were significantly inversely associated with percent density (PD), and positively associated with breast volume (BV). The strongest inverse correlations with PD were observed for body fat % (r= -0.68, P<0.001), and waist (r= -62, P<0.001). For BV, the strongest positive correlations were observed for waist r=0.75, P<0.001) and current BMI (r=0.76, P<0.001). In multivariable regression models, body fat % had the strongest association with PD (beta coefficient (ß)= -0.50, P<0.001). BMI during the three time points were each inversely associated with PD, with BMI at age 18 having the largest beta coefficient (ß= - 0.50, P<0.001) compared with current BMI (ß= -0.45, P<0.001) and BMI at age 30 (ß= - 40, P<0.001). After controlling for BMI at age 18, weight gain at all time periods was associated with a decrease in PD and an increase in BV. The largest decrease in PD was observed for weight gain from age 18 to current age (ß= - 8.5, P<0.001) comparing women who gained >25kg to those who had stable weight (gained between 0-5kg) during this period. Conclusions: Weight gain in early adulthood is associated with reductions in PD and increases in BV in premenopausal women. Our findings highlight the need for mechanistic studies focusing on early adulthood to provide a better understanding of how adiposity relates to mammographic density, and possibly breast cancer development in premenopausal women. Citation Format: Aliya Alimujiang, Graham Colditz, Catherine Appleton, Adetunji T. Toriola. Adiposity, change in adiposity during adulthood and mammographic density in premenopausal women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4248. doi:10.1158/1538-7445.AM2017-4248