Is neoadjuvant chemotherapy necessary for T2N0-1M0 hormone receptor-positive/HER2-negative breast cancer patients undergoing breast-conserving surgery?

Introduction: For HR-positive/HER2-negative patients who can undergo breast-conserving surgery (BCS) but have a tumor size of 2–5 cm or 1–3 lymph node metastases, neoadjuvant chemotherapy (NAC) is still controversial. Methods: Patients with T2N0-1M0 HR-positive/HER2-negative BC who underwent BCS between 2010 and 2017 were selected from the SEER database. Propensity score matching (PSM) was used to minimize the influence of confounding factors. The overall survival (OS) and breast cancer-specific survival (BCSS) of patients were estimated by Kaplan‒Meier curves and Cox proportional hazard models. Independent prognostic factors were included to construct a nomogram prediction model. Results: A total of 6475 BC patients were enrolled, of whom 553 received NAC and 5922 received adjuvant chemotherapy (AC). In the T2N0-1M0 population and T2N1M0 subgroup, AC patients before PSM had better OS and BCSS than NAC patients. After PSM, there was no significant difference in OS or BCSS between the two groups. However, in the T2N0M0 subgroup, there was no difference in survival between the AC and NAC groups before and after PSM. Stratified analysis revealed that for complete response (CR) patients, survival was roughly equivalent between the NAC and AC groups. However, the survival of no response (NR) and partial response (PR) patients was significantly worse than that of AC patients. Cox analysis revealed that radiotherapy after BCS was an independent protective factor for OS. NAC is an independent risk factor for NR and PR patients. The nomogram has good prediction efficiency. Conclusion: NAC before BCS is not necessary for T2N0-1M0 HR-positive/HER2-negative BC patients.