Exploring the impact of race, ethnicity, and BMI on neoadjuvant hormonal treatment outcomes.

e12590 Background: Neoadjuvant hormonal therapy (NHT) is a treatment option for estrogen receptor-positive (ER+) breast cancer (BC) in postmenopausal women. Utilization of NHT varies significantly and treatment responses may vary across different patient populations. This abstract explores a cohort of patients who underwent NHT at our center, delving deeper into patient characteristics and outcomes to enhance the understanding of factors driving disparities. Methods: This is a retrospective, IRB-approved cohort study including 128 patients who received NHT at a single institution from 1/2005 to 1/2020. Inclusion criteria were postmenopausal patients with ER+/HER2 negative breast cancer, NHT treatment with an aromatase inhibitor (AI), and subsequent surgery. BMI was classified into categories (<18.5, 18.5-24.9, 25-29.9, 30-34.9, 35-39.9, and >40 ). Response to treatment was defined as a change in TNM staging after neoadjuvant treatment (stage decrease, no change, stage increase) from initial clinical exam and imaging to post-treatment surgical pathology. Comparative analyses assessed the correlation between race, ethnicity, BMI, and clinical outcomes. Results: The median age at diagnosis was 62 (range 46-91). Stage, BMI, race/ethnicity distributions summarized in table. After NHT, 23.6% were downstage by TNM criteria, 55.9% of patients had no change, and 20.5% had progressed. Of the 55.5% who did not change by TNM criteria, 81% did see a reduction in size of primary tumor by largest dimension by at least 10% from treatment. After surgery, adjuvant chemotherapy was recommended by the treating oncologist in 77% of the patients. Recommendation for chemotherapy correlated with response to treatment (p<0.001) and with initial stage (p<0.001). No statistically significant differences were found between the response to NHT and race or ethnicity. However, there was a correlation with increasing BMI and poorer response NHT (p=0.012). Of the four patients with BMI >40, none saw a positive response to treatment and two of them had progression of disease. Progression on NHT was correlated with worsened five-year survival even if patients received adjuvant chemotherapy (p<0.001). Conclusions: These findings underscore the importance of incorporating patient characteristics into neoadjuvant treatment decisions in ER+ BC. Our findings suggest that NHT may not be effective in patients with higher BMI. Poorer five-year survival in those who responded poorly to NHT was observed, even when controlling for whether adjuvant chemotherapy was given, which may be expected as hormonal therapy is also the crux of the adjuvant treatment for these patients. These data were collected prior to the use of CDK4/6 inhibitors in the adjuvant setting for high risk ER+ BC, but this could serve as a potential adjuvant strategy for those who did not respond to NHT. Additional research into treating patients with ER+ breast cancers with elevated BMI as well as adjuvant treatment for those who do not respond to NHT is recommended. Patient characteristic Percentage Stage at Diagnosis IIA 31.2 IIB 24.0 IIIA 21.6 IIIB 20.8 IIIC 2.4 Race/Ethnicity White, Hispanic 64.1 Black, Nonhispanic 19.5 White, Nonhispanic 14.1 BMI <18.5 0 18.5-24.9 25.0 25-29.9 37.5 30-34.9 22.7 35-39.9 9.4 >40 5.5