Survival outcomes of neoadjuvant endocrine therapy versus chemotherapy in hormone receptor–positive breast cancer: An NCDB analysis.

Abstract

e12669 Background: Neoadjuvant endocrine therapy (NET) and neoadjuvant chemotherapy (NCT) are accepted treatment strategies for postmenopausal women with hormone receptor–positive (HR+), HER2-negative invasive breast cancer (IBC). Contemporary comparisons of surgical outcomes and survival remain limited. Methods: Women aged ≥50 years with stage II–III, HER2-negative (IHC 0–1+ or 2+/FISH-negative), HR+ IBC diagnosed from 2010–2017 were identified from the NCDB. Patients received NET or NCT followed by surgery and adjuvant endocrine therapy were included. Overall survival (OS) was analyzed using Kaplan–Meier methods and multivariable Cox regression Results: Among 6,857 patients, 1,619 (23.6%) received NET and 5,238 (76.4%) received NCT. NET was independently associated with older age, higher comorbidity burden, government insurance, greater travel distance ( > 200 miles), and T2 tumors, while NCT was associated with community facility treatment, higher tumor grade, and greater nodal involvement. NET was associated with lower odds of mastectomy compared with NCT (19.4% vs 80.6%; adjusted odds ratio [aOR] 0.63, 95% CI 0.53–0.75). Adjuvant radiation use did not differ after adjustment. NET was associated with lower odds of achieving at least a partial response (aOR 0.58, 95% CI 0.44–0.76), although longer NET duration ( > 115 days) was associated with reduced mastectomy rates. Median follow-up was 178 months with similar median OS; 5 yr survival at 94.6% vs 95.2%, 9 yr survival at 48.6% vs 52.1% for NET vs NCT respectively. NCT conferred a modest survival advantage in the full cohort (adjusted hazard ratio [HR] 0.89, 95% CI 0.81–0.98; p = 0.016) and in ER+/PR+ tumors (HR 0.85, 95% CI 0.77–0.94; p = 0.002), with no difference in single HR-positive disease. Conclusions: NET is preferentially used in older, more comorbid patients and those with geographic or socioeconomic barriers and is associated with lower mastectomy rates and largely comparable survival to NCT. Interpretation is limited by the retrospective design, potential selection bias, availability of Oncotype DX only in subset of pts, and lack of specific therapy used.