Abstract B122: Differential response to neoadjuvant endocrine therapy for Black and White women in NCDB

Abstract Introduction: Black/African American (BAA) women have 4x higher mortality from hormone receptor positive breast cancer (HR+BC) than White women. Despite this disparity, HR+BC across races is treated with relative uniformity: endocrine therapy. Previous studies have focused on the adjuvant setting. We examined use of neoadjuvant endocrine therapy (NET) in BAA and White women in the National Cancer Database (NCDB) and assessed treatment response by race. Methods: We queried the NCDB for women with clinical stage I-III HR+BC treated between the years 2004-2017 with NET. Patients receiving neoadjuvant chemotherapy and with unknown surgery or race were excluded. Time between initiation of NET and date of first operation was used to proxy duration of NET. Our primary objective was to compare in BAA and White women changes in tumor size and nodal status after NET, considering duration of treatment. Univariate and multivariable logistic regression was performed. Results: The final sample included 9,864 White and 1,090 BAA women. BAA women were disproportionately excluded for receipt of neoadjuvant chemotherapy (OR=1.8, 95%CI 1.6-1.9). Sociodemographic variables differed between the two groups with p<0.001, including payor status (12.8% BAA with Medicaid vs 5.2% White), income (33.8% BAA with <$38000 median household income vs 11.9% White), location (73.4% BAA living in metropolitan areas vs 55.4% White), and treatment facility (45.7% and 28.3% BAA at an academic center and community hospital respectively vs 32.7% and 37% White, respectively). Median duration of NET was higher in BAA (128 days) than Whites (114 days), p<0.001. After excluding those with unknown pT/N/M, 3,521 White and 365 BAA women were evaluated for NET response. Overall, 0.8% downstaged to pT0 or pTis and 0.9% upstaged to Stage IV disease. Women downstaged from only Clinical Stage I-II disease whereas all but 2 women upstaged from Stage II or higher. Compared to White women, BAA women were more likely to present as node positive (OR=1.6, 95%CI 1.3-2.1) or Stage III (OR=1.5, 95%CI 1.1-2.0) and be treated with NET for >24 weeks (OR=1.5, 95%CI 1.2-1.8). On multivariate analyses, compared to White women, BAA women were more likely to downstage to pT0/Tis. BAA women who downstaged to pT0/Tis had longer duration of NET than their White counterparts (median 241 vs 167.5 days, respectively); race was a significant predictor of downstaging on multivariate analysis adjusting for duration of NET and clinical stage (OR=2.85, p=0.016 for BAA). Compared to White women, BAA women were more likely to upstage to Stage IV on multivariate analysis despite being treated longer with NET and controlling for stage at presentation. Conclusion: This study offers important insight into the heterogeneity of HR+BC biology across races in response to NET. While longer duration of NET appears beneficial for BAA women presenting with lower stage clinical disease, it did not demonstrate benefit in BAA women with higher clinical stage. These findings suggest a dichotomous presentation of HR+BC biology in BAA women. Citation Format: Veronica Jones, Mary Schroeder, Mya Roberson, James De Andrade, Ingrid Lizarraga. Differential response to neoadjuvant endocrine therapy for Black and White women in NCDB [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr B122.