Neoadjuvant Chemotherapy or Endocrine Therapy for Invasive Ductal Carcinoma of the Breast with High Hormone Receptor Positivity and Human Epidermal Growth Factor Receptor 2 Negativity

Abstract

Importance: Although neoadjuvant endocrine therapy (NET) is an alternative to chemotherapy for strongly hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (ERBB2)-negative breast cancer, evidence is currently lacking regarding the probable survival outcomes of NET in comparison with those of neoadjuvant chemotherapy (NACT) for this cancer. Objective: To evaluate all-cause mortality among patients with strongly HR-positive and ERBB2-negative breast cancer treated with NET vs NACT. Design, Setting, and Participants: This cohort study included patients with a diagnosis of invasive ductal carcinoma (IDC) with strong HR positivity and ERBB2 negativity, treated between January 1, 2009, and December 31, 2016, with follow-up from the index date (ie, date of IDC diagnosis) to December 31, 2018. The data came from the Taiwan Cancer Registry Database. Data were analyzed from January to November 2020. Exposures: NET vs NACT for IDC with strong HR positivity and ERBB2 negativity. Main Outcomes and Measures: The primary end point was all-cause mortality. Propensity score matching was performed, and Cox proportional hazard models were used to analyze all-cause mortality among patients undergoing different neoadjuvant treatments. Results: A total of 640 patients (297 [46.4%] aged 20-49 years) undergoing NET (145 patients [22.7%]) or NACT (495 patients [77.3%]) were eligible for further analysis. In the multivariate Cox regression analyses, the adjusted hazard ratio (aHR) for all-cause mortality among the NET cohort compared with the NACT cohort was 2.67 (95% CI, 1.95-3.51; P