ASPO Abstracts

Breast density and risk of invasive breast cancer among older women undergoing mammography: The Breast Cancer Surveillance Consortium cohort study

Authors: Braithwaite D, Miglioretti DL, Zhu W, Demb J, Trentham-Dietz A, Sprague B, Tice JA, Onega T, Henderson LM, Buist DSM, Walter LC, Kerlikowske K

Category: Early Detection & Risk Prediction, Survivorship & Health Outcomes/Comparative Effectiveness Research
Conference Year: 2018

Abstract Body:
Objective: This study examined whether breast density is associated with risk of breast cancer in women age 65 years undergoing screening mammography in community practice. Methods: We used prospective cohort data between 1996 and 2012 from the Breast Cancer Surveillance Consortium (BCSC). We calculated separate cumulative incidence models for breast cancer incidence according to Breast Imaging Reporting and Data System (BI-RADS) breast density for women ages 65-74 and ages 75. Multivariable Cox proportional hazards regression models were fitted to determine the risk of invasive breast cancer adjusted for BCSC registry, race/ethnicity, BMI, hormone therapy use and benign breast disease. Results: Among the 403,268 women included in the study, approximately 40% were ages 75. The annual incidence rate of invasive breast cancer increased with increasing breast density among women ages 65-74 [BI- RADS fatty breasts: 2.2% (95% CI, 2.1-2.4%) vs. heterogeneously or extremely dense breasts: 4.7% (95%CI, 4.6- 4.9%)] and women ages 75+ [BI-RADS fatty breasts: 2.3% (95% CI, 2.1-2.5%) vs. heterogeneously or extremely dense: 4.3% (95% CI, 4.1-4.5%)]. Women with BI-RADS fatty breasts had a decreased risk of breast cancer among women ages 65-74 [HR: 0.66 (95% CI: 0.58-0.78%) and women ages 75 [HR: 0.73 (95% CI: 0.62- 0.87%). Women with BI-RADS heterogeneously or extremely dense breasts were found to have increased risk of breast cancer among women ages 65-74 [HR: 1.39 (95% CI: 1.28-1.51%)] and women ages 75 [HR: 1.23 (95% CI: 1.10-1.37%)]. Conclusions: Older women with higher BI-RADS density had a significantly increased risk of breast cancer. These findings add further evidence that breast density continues to be associated with an increased risk of breast cancer, even among women age 75 years.

Keywords: breast density breast cancer aging older women mammography