Abstract
Introduction: Neoadjuvant hormonal therapy (NHT) is a potential treatment strategy for estrogen receptor-positive (ER+) breast cancer (BC) in postmenopausal women. Despite its clinical benefits, utilization of NHT varies significantly and anecdotal experience suggests that treatment responses may vary across different patient populations. Methods: This is an IRB approved retrospective cohort study of 170 consecutive postmenopausal patients with ER+/HER-2 negative BC who received neoadjuvant hormonal therapy (NHT) at a single institution from 1/2005 to 6/2018. All subjects were treated with anastrozole 1 mg daily until maximal clinical response. In a subset of 96 patients with surgical pathology available for review by a single pathologist, quantitative ER and PR were measured by decile and Ki67 was categorized as low (0-15%), intermediate (16-30%) and high (>30%). BMI was classified as <18.5 (underweight), 18.5-24.9 (normal), 25-29.9 (overweight), and ≥30 (obese). Comparative analyses assessed the correlation between race, ethnicity, BMI, and clinical outcomes. Results: The median age at diagnosis was 62 (range 46-91), and median size of the breast mass was 5.3 cm (range 1.5-19.0 cm). At start of treatment, 27% of patients were stage IIA, 29% IIB, 22% IIIA, and 18% IIIB. The majority of patients were White (77%) and Hispanic (71%). 23% of patients were Black. Regarding BMI, 37% were in the normal range, 38% were overweight, and 25% obese. Pathology review showed that the large majority of tumors had 91-100% ER positivity (66%) or 81-90% ER positivity (19%). PR positivity was more variable with only 21% at 91-100% PR positivity and 35% of patients with <50% PR positivity on IHC. The largest amount of patients (48%) were Ki67 low, 17% were intermediate, and 34% were Ki67 high. Higher BMI was associated with higher ER expression (p=0.007) and higher Ki67 (p=0.042). There was no association between ER/PR expression and race or ethnicity. The median duration of NHT was 6 months, with treatment durations extending up to 28 months. Pathological complete response (PCR) was observed in 3 tumors. All patients with a PCR were stage IIB at diagnosis, White, Hispanic, and overweight. Progression of disease occurred in 10 patients of which 40% were Black, 60% were Hispanic, 30% were overweight, and 40% were obese. Although pCR can be used as a surrogate endpoint for response to neoadjuvant therapy, there is no standard method of determining a significant response to NHT. In our cohort, the decision to give adjuvant chemotherapy was individualized for each patient based on the perceived response to NHT. The patients given adjuvant chemotherapy were felt to be at higher risk of relapse than those who received adjuvant hormonal therapy alone. Overall, 61% of patients required adjuvant chemotherapy after NHT. White women were more likely to receive adjuvant chemotherapy than Black women 66% vs 45% (p=0.019). There was a significant correlation between higher Ki67% and the need for adjuvant chemotherapy (p=0.030), but not between degree of ER positivity, PR positivity, or BMI. Conclusion: The use of NHT potentially prevented adjuvant chemotherapy use in 39% of postmenopausal women with ER+/HER-2 negative BC. There appear to be disparities in response to NHT based on race but not on BMI or ethnic group. Additional research is needed to investigate molecular underpinnings between race/ethnicity/BMI and response to NHT.
Citation Format: Traci King, Priscila Barreto Coelho, Youley Tjendra, Judith Hurley, Sofia George. Exploring the Impact of Race, Ethnicity, and BMI on Neoadjuvant Hormonal Treatment Outcomes [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P3-01-15.