Trends in primary endocrine therapy utilization among patients with early-stage ER+/HER2− breast cancer who do not undergo surgery: A National Cancer Database analysis.

Abstract

44 Background: Primary endocrine therapy (pET) is a mainstay of cancer treatment for patients with estrogen receptor-positive (ER+) breast cancer who are unfit for surgery. As the multidisciplinary breast oncology teams continue to personalize cancer therapies for patients, we have noticed pET being expanded to other groups. Thus, we sought to characterize pET utilization over time, defined by endocrine therapy use as the first cancer-directed therapy, in the absence of surgical intervention during their cancer care. Methods: The National Cancer Database was used to identify female patients with ER+HER2- clinical T1-2N0M0 breast cancer diagnosed from 2019-2022 who did not undergo definitive surgery. The proportion of patients receiving pET as their first oncologic therapy and its utilization over time were catalogued. Comparisons in pET utilization across study years, and within Charlson-Deyo (CD) comorbidity groups were assessed using chi-square tests. Results: Overall, 17,552 patients (median age 75) met the inclusion criteria. The study cohort was predominantly White (77.3%) and Black patients (12.5%). Implementation of pET in patients with early-stage, ER+ HER2- breast cancer stayed relatively consistent throughout 2019-2022, with rates of 34.7%, 38.3%, 37.1% and 36.8% respectively. However, these patterns varied significantly according to the CD comorbidity score (p<0.001). Among patients with no comorbidities (CD score 0), pET use rose significantly from 29.7% in 2019 to 32.3% in 2022 (p=0.002). In contrast, patients with a CD score of 1 to 3+ demonstrated consistent pET utilization rates throughout the study period (Table). Conclusions: Overall, pET without definitive surgery remained consistent from 2019-2022 among patients with early-stage (T1-2N0M0) ER+ HER2- breast cancer, particularly among those with significant comorbidity burden. Notably, nearly one-third of patients without documented comorbidities also received pET, with utilization increasing from 2019-2022. Whether the COMET trial, similar de-escalation initiatives, or COVID-19 related changes have influenced this expanded utilization in surgically fit candidates is unknown. Future work aims to better characterize additional patient, disease, and clinical factors associated with this treatment approach. pET utilization by Charlson-Deyo score and year. 2019 2020 2021 2022 0 29.7% 34.2% 32.6% 32.3% 1 49.4% 49.1% 51.1% 50.4% 2 59.0% 57.4% 58.0% 57.4% 3+ 53.8% 55.9% 54.5% 53.0%