Abstract C067: Race and age-related differences in adjuvant chemotherapy use for hormone receptor-positive/HER2-negative breast cancer by genomic risk

Abstract Background: The TAILORx and RxPONDER trials confirmed postmenopausal women with hormone receptor-positive (HR+)/HER2– breast cancer and ≤3 involved lymph nodes can safely omit chemotherapy (CT) with an OncotypeDX recurrence score (RS) of <26. However, these studies showed CT benefit in premenopausal patients, possibly due to effect of CT on ovarian function. This study assessed trends and racial differences in adjuvant CT use for early-stage, HR+/HER2– breast cancer by age, RS, and nodal status in the post-RxPONDER era. Methods: The National Cancer Database (NCDB) was queried for women diagnosed with Stage I-III, HR+/HER2– breast cancer from 2010 to 2022 who had undergone breast surgery, had OncotypeDX testing, and were eligible for endocrine therapy. Patients were stratified by menopausal status (measured by age: ≤50 or >50 years) and lymph node involvement (pN0 or pN1+). RS was categorized as low (RS ≤10), intermediate (RS 11-25), or high (RS ≥26) risk. We performed logistic regression, controlling for RS and sociodemographic and clinical factors. Results: Of 504,937 women (mean age 60.0 years [SD 10.7]), 81.3% were White, 8.1% Black, 5.4% Hispanic, and 4.3% Asian or Pacific Islander (API); 81.4% had pN0 tumors; 78.8% were postmenopausal. 61.0% had intermediate RS, followed by 24.6% low RS and 14.4% high RS. In premenopausal, pN0 women, adjuvant CT use for low RS decreased from 6.5% in 2010 to 0.9% in 2022 and for intermediate RS decreased from 29.6% in 2010 to 11.1% in 2022. However, in premenopausal, pN1+ women, CT use for low RS declined from 33.3% in 2010 to 12.7% in 2019 but has subsequently risen to 25.7% in 2022 following publication of RxPONDER. Similarly, for intermediate RS, adjuvant CT usage declined from 55.8% in 2010 to 38.1% in 2019 but increased to 48.9% in 2022. Among postmenopausal women, CT use for low and intermediate RS continued to decline from 2010 to 2022 in both pN0 and pN1+ disease. Regardless of nodal or menopausal status, adjuvant CT usage for high RS was constant over the study timeframe. Compared to White women, API (adjusted odds ratio [AOR], 0.86; 95% CI, 0.78-0.95) or Black (AOR, 0.90; 95% CI, 0.81-0.98) premenopausal women with pN0 tumors had lower odds of adjuvant CT receipt; Black women with N1+ tumors also had lower odds of CT receipt (AOR, 0.83; 95% CI, 0.72-0.97). In the postmenopausal cohort, API (AOR, 0.86; 95% CI, 0.79-0.94) or Black (AOR, 0.91; 95% CI, 0.86-0.97) pN0 women had lower odds of adjuvant CT receipt than White women; the odds of CT receipt were also lower in Black women with pN1+ tumors (AOR, 0.91; 95% CI, 0.84-0.99). Conclusions: In this NCDB analysis of early-stage, HR+/HER2– breast cancer, adjuvant CT use almost doubled in premenopausal women with pN1+ tumors and a low or intermediate RS from 2019 to 2022 but decreased for those with pN0 tumors, coinciding with TAILORx and RxPONDER trials. Our findings also noted API and Black women were less likely to receive adjuvant CT, even in pN1+ disease, highlighting racial differences in CT utilization in the era of genomically guided care. Citation Format: Jincong Q. Freeman, Daniel S. Peiffer, Nan Chen, Sarah P. Shubeck, Sudha R. Yarlagadda, Rita Nanda, Dezheng Huo, Frederick M. Howard, Poornima Saha. Race and age-related differences in adjuvant chemotherapy use for hormone receptor-positive/HER2-negative breast cancer by genomic risk [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr C067.