Adjuvant radiotherapy may not confer survival benefit for cT1-2N1M0 breast cancer patients who undergo surgical treatment following neoadjuvant chemotherapy: an analysis based on SEER

Abstract

Abstract Background The guidelines for postoperative radiotherapy in breast cancer are mainly based on studies of patients who received initial surgical treatment. However, with the widespread use of neoadjuvant chemotherapy (NAC), the potential benefit of postoperative radiotherapy for patients with cT1-2N1M0 has been a subject of controversy. Therefore, determining whether postoperative radiotherapy provides a survival benefit for this group of patients can guide doctors in their postoperative treatment decisions. Methods Clinical data of 1092 female patients with cT1-2N1M0 breast cancer who received NAC treatment were retrospectively analyzed from the Surveillance, Epidemiology, and End Results (SEER) database. After propensity score matching (PSM), the impact of postoperative radiotherapy on overall survival (OS) and cancer-specific survival (CSS) was compared, and subgroup analysis was performed. Finally, univariate and multivariate Cox regression analysis was used to explore the potential risk factors for OS and CSS in patients with cT1-2N1M0 breast cancer. Results Regardless of PSM status, compared to no postoperative radiotherapy, postoperative radiotherapy was associated with improved OS in cT-2N1MO breast cancer patients who received NAC (10-year OS rate, PSM pre: 78.7% vs. 71.1%, P = 0.015; PSM post: 83.1% vs. 71.1%, P = 0.021). However, postoperative radiotherapy did not confer a benefit in CSS for female cT1-2N1MO breast cancer patients who received NAC, regardless of PSM status (10-year CSS rate, PSM pre: 81.4% vs. 76.2%, P = 0.085; PSM post: 85.8% vs. 76.2%, P = 0.076). Subgroup analyses revealed that radiotherapy improved CSS in the 2010–2012 diagnosis (HR 0.5, 95% CI: 0.25–0.98, P = 0.043) and right-sided (HR 0.42, 95% CI: 0.18–0.98, P = 0.045) subgroups. Univariate Cox regression analysis showed that factors associated with poor OS included ≥ 4 positive lymph nodes, HR-/HER2-, and no postoperative radiotherapy, while in multivariate Cox regression analysis, only ≥ 4 positive lymph nodes and HR-/HER2- were significant independent factors associated with reduced OS. Factors associated with poor CSS in univariate Cox regression analysis included black and other races, 1–3 positive lymph nodes, ≥ 4 positive lymph nodes, and HR-/HER2-. In multivariate Cox regression analysis, these factors remained significant independent factors associated with reduced CSS. Conclusion Our study results suggest that additional postoperative radiotherapy may not confer a survival benefit in cT1-2N1MO patients who received NAC. This still needs to be confirmed by more prospective randomized controlled trials.