Abstract P4-10-08: Family history of breast cancer and mammographic density in premenopausal women
Authors: Han Y , Zong X , Colditz GA , Toriola AT 
Published: May 2019

Abstract
Introduction: Mammographic density and family history of breast cancer (FHBC) are independent risk factors for breast cancer. Women with dense breasts have a 4-6-fold increased risk of breast cancer and women with FHBC have a 1.5-3-fold increased risk of breast cancer. However, there is little data on the associations of FHBC with mammographic density, especially in premenopausal women. To address this, we investigated the associations of FHBC in first-degree relatives with mammographic density in premenopausal women.
Methods: We used data from 375 cancer-free premenopausal women who were during routine screening mammography at Washington University in St. Louis in 2016. We used Volpara to measure volumetric measures of density including volumetric percent density, dense volume, and non-dense volume. We collected data on first-degree relatives (mother, sister) and numbers of first degree relatives (0, 1, ≥2) with a positive FHBC. We used multivariable linear regression model, adjusted for age, BMI, parity, race, age at menarche, and alcohol consumption, to determine the associations of FHBC and log-transformed volumetric percent density, dense volume, and non-dense volume. Beta coefficients (β) were evaluated and back transformed for easier interpretation.
Results: The mean age of participants was 47.5 years (range=32-58). The mean BMI was 30.8 kg/m2 (range =17.9-63.1). Volumetric percent density was 25% (p-value&lt;0.001) higher in women who had a FHBC compared with women who had no FHBC. The associations appeared confined to women with a positive family history in mothers but not those with a positive family history in sisters. Volumetric percent density was 31% higher (p-value&lt;0.001) among women with a positive FHBC in mothers compared to those without a positive FHBC in mothers, but 8% higher (p-value=0.45) among women with a positive FHBC in sisters compared to those without a positive FHBC in sisters. The associations of FHBC with dense volume were similar to those of volumetric percent density in all the analyses. For instance, dense volume was 16% (p-value=0.006) higher in women who had a FHBC compared with women who had no FHBC.
Table 1.Associations of family history of breast cancer (FHBC) and volumetric percent density (VPD), and dense volume (DV) in 375 premenopausal women*.FHBCNVPD (%) DV (cm3 ) Beta (95% CI)P-valueBeta (95% CI)P-valueNo275Ref Ref Yes871.25 (1.12,1.41)&lt;0.0011.16 (1.04,1.29)0.007Unknown131.00 (0.76,1.30)0.990.74 (0.58,0.95)0.017*Adjusted for age, BMI, parity, race, age at menarche, and alcohol consumption.
Conclusions: Premenopausal women with a first-degree FHBC have higher volumetric percent density. Our findings could help identify high-risk women who may benefit from targeted screening.
Citation Format: Han Y, Zong X, Colditz GA, Toriola AT. Family history of breast cancer and mammographic density in premenopausal women [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-10-08.