Abstract P5-08-01: Breast cancer risk thresholds as a predictor of chemoprevention uptake in the Athena Breast Health Network
Authors: Huilgol Yash S , Keane Holly , Shieh Yiwey , Tice Jeffrey , Ziv Elad , Madlensky Lisa , Sabacan Leah , Acerbi Irene , Che Mandy , Fiscalini Allison Stover , Anton-Culver Hoda , Borowsky Alexander D , Hunt Sharon , Naeim Arash , Parker Barbara , van 't Veer Laura J ,   Athena Breast Health Network Investigators and Advocate Partners and Laura J Esserman
Published: March 2020

Abstract
Background: Large-scale chemoprevention trials validated endocrine risk reduction strategies to lower breast cancer risk. We sought to understand the risk at which women are likely to adopt chemoprevention. A 5-year Gail risk of 1.67% or above is considered elevated risk, and the FDA indication for prescribing chemoprevention. We examined chemoprevention use in the Athena Breast Health Network (Athena), which includes approximately 100,000 women who are screened by mammography at Sanford Health, UC Davis, UC Irvine, UC Los Angeles, UC San Diego, and UC San Francisco.
Methods: We calculated the Gail risk score for women who had completed an Athena online intake survey distributed before being seen at screening centers; this survey included questions about chemoprevention usage. First, we analyzed 16,518 surveys of 9,318 unique women without breast cancer or DCIS who received breast cancer screening at UCSF from 2011- 2018 and who consented to research. These women also self-reported use of chemoprevention. We stratified Gail risk scores by a threshold of 1.67%, and by percentiles to identify those women in the top 2.5% by age. We compared current chemoprevention use in these different breast cancer risk strata, and factors associated with its use. An analysis including all 100,000 women in the Athena Network will be presented at SABCS.
Results: Overall, at UCSF, 48 of 9,318 women (0.51%) reported current chemoprevention use. The 5-year Gail risk was greater than 1.66% in 3,675 of 9,318 women (39%), of whom 205 (2.2%) were in the top 2.5% of risk by age. Chemoprevention use was reported by 13 of 205 (6.3%) women in the top 2.5% of risk by age (mean Gail risk 5.6%), as compared to 41 of 3,675 (1.1%) who were at Gail above 1.66% (mean Gail = 3.9%). Women in the top 2.5% and those with Gail risk &gt;1.66% were significantly more likely to be using chemoprevention p&lt; 0.01 for each respectively). Chemoprevention uptake was correlated with the joint effect of the top 2.5% of risk by age and increasing Gail score (OR = 10.25; P = 0.009). Preliminary results were consistent among the 100,000 women in the Athena registry (analysis ongoing). In addition, chemoprevention use was more likely in older women (OR = 1.10; P &lt; 0.01, for every year of age) and in those women with Ashkenazi ancestry on both sides of the family compared to none (OR = 2.32; P = 0.02). Race and education were not associated with use of chemoprevention.
Discussion: Women with higher Gail scores in the top 2.5% of risk by age are positively associated with current chemoprevention use (6.34%). Importantly, this analysis presents a risk-stratified, population-level risk reduction strategy, using the top 2.5% risk threshold by age. It provides an opportunity to specifically target chemoprevention to women at highest need to reduce their breast cancer risk. In the WISDOM Study (NCT02620852), we are prospectively testing active outreach based on breast cancer risk in the top 2.5% of risk by age, and have developed a breast health decisions aid to standardize communication of risk-reducing options.
Citation Format: Yash S Huilgol, Holly Keane, Yiwey Shieh, Jeffrey Tice, Elad Ziv, Lisa Madlensky, Leah Sabacan, Irene Acerbi, Mandy Che, Allison Stover Fiscalini, Hoda Anton-Culver, Alexander D Borowsky, Sharon Hunt, Arash Naeim, Barbara Parker, Laura J van 't Veer, Athena Breast Health Network Investigators and Advocate Partners and Laura J Esserman. Breast cancer risk thresholds as a predictor of chemoprevention uptake in the Athena Breast Health Network [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-08-01.