Neoadjuvant endocrine therapy often leads to breast and axilla‐conserving surgery in stages II and III hormone receptor‐positive breast cancer patients: A registry study

In stages II and III hormone receptor positive (HR+) breast cancer, selecting patients for primary surgery (PS) or neoadjuvant therapy remains challenging. This study assessed the occurrence of minimally invasive surgery in the case of PS, neoadjuvant endocrine therapy (NET), and neoadjuvant chemotherapy (NACT). This cohort study included women diagnosed with stages II and III, HR+ breast cancer in 2020-2022 in the Netherlands. Women with positive human epidermal growth factor receptor 2 (HER2+) cancer were excluded. Outcomes focused on surgical techniques and additional treatment. Of the 7809 patients, 4046 (51.8%) underwent PS, 956 (12.2%) received NET and 2807 (35.9%) NACT. NET patients were older (median: 71 years [33-94]), while NACT patients had larger tumors and more lymph node involvement (p < .001). Breast-conserving surgery (BCS) was the first procedure in 2153 (53.2%) PS women, in 694 (72.6%) NET women and 1564 (55.7%) NACT cases. There was no difference regarding free surgical margins in NET versus NACT patients (p = .421). After adjusting for T-stage, BCS occurred significantly more frequently after NET (p < .001). Minimal invasive surgery on the axilla was common after NET (83.9%) and NACT (81.5%). In the PS group, 85% received adjuvant systemic therapy. Optimizing patient selection for neoadjuvant strategies could reduce surgical morbidity. NET was frequently associated with BCS, showed comparable surgical margin outcomes to NACT, and contributed to reduced axillary surgery. These findings suggest that NET is an effective strategy, compared to PS, to facilitate less invasive surgery on the breast and axilla, in HR+/HER2-, stages II and III breast cancer.