Abstract 3488: Associations of circulating hormones with mammographic density in postmenopausal women referred to diagnostic breast biopsy
Authors: Fan Shaoqi , Pfeiffer Ruth M. , Hada Manila , Falk Roni T. , Mullooly Maeve , Oh Hannah , Geller Berta , Vacek Pamela , Weave Donald , Shepherd John , Wang Jeff , Herschorn Sally , Brinton Louise A. , Xu Xia , Sherman Mark E. , Trabert Britton , Gierach Gretchen L. 
Published: September 2020

Abstract
Introduction Elevated mammographic density (MD) is a strong and independent risk factor for breast cancer, though underlying mechanisms are unclear. Prior studies have suggested that increased cumulative exposure to sex-steroid hormones and growth factors may impact both MD and MD-related breast cancer risk; however, most studies have only evaluated individual hormones. In this study, we simultaneously explored the relationship between 29 circulating hormones and growth factors with MD among postmenopausal women undergoing diagnostic breast biopsy.
Methods We used data from 89 postmenopausal women, aged 44-65, who had complete measurements of 29 serum hormones from a single pre-biopsy blood draw (i.e., sex-steroid hormones: 15 estrogen/estrogen metabolites, 7 progesterone/progesterone metabolites; and non-sex hormones: insulin-like growth factor I and binding proteins (IGFBPs) 2-7). Volumetric MD (% fibroglandular volume) was assessed in pre-biopsy digital mammograms using single X-ray absorptiometry. Sufficient dimension reduction methods were used to compute a composite marker score that accommodates correlations among hormones and their relationship to MD. Backward elimination was applied to select log-transformed hormones contributing to the score at α=0.05; multivariable linear regression was used to further examine associations between selected hormones and MD within a single model, adjusting for age and BMI.
Results Pearson correlations between hormones were moderate-to-strong. Dimension reduction methods identified 6 hormones as associated with MD (p&lt;0.05): estradiol, 2-hydroxyestradiol, 2-methoxyestrone, 16-ketoestradiol, IGFBP-2, and 17α-hydroxyprogesterone, in models that considered MD as either continuous or dichotomous (&gt;median vs. ≤median); BMI was consistently identified as the most significant predictor of MD (P &lt;0.0001). In a multivariable linear regression model that included these 6 hormones, in addition to age and BMI, higher levels of 2-methoxyestrone, IGFBP-2, and 17α-hydroxyprogesterone were significantly associated with increased MD, whereas higher levels of age and BMI were significantly associated with lower MD.
Conclusions We identified 6 out of 29 correlated hormones that were significantly associated with MD among postmenopausal women. For several, the directions of their associations with MD were comparable to those observed in prior studies that have separately evaluated these hormones in relation to breast cancer risk. We plan to further explore how circulating hormones concurrently affect MD in premenopausal women, accounting for menstrual cycle phase. Incorporation of dimension reduction methods in studies of multiple correlated hormones can help uncover new etiologic insights into the role of hormones and growth factors in MD and breast carcinogenesis and inform strategies for prevention.
Citation Format: Shaoqi Fan, Ruth M. Pfeiffer, Manila Hada, Roni T. Falk, Maeve Mullooly, Hannah Oh, Berta Geller, Pamela Vacek, Donald Weave, John Shepherd, Jeff Wang, Sally Herschorn, Louise A. Brinton, Xia Xu, Mark E. Sherman, Britton Trabert, Gretchen L. Gierach. Associations of circulating hormones with mammographic density in postmenopausal women referred to diagnostic breast biopsy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3488.