Assessment of Radiotherapy as a Standalone Treatment Following Neoadjuvant Chemotherapy in Nonmetastatic Breast Cancer: A SEER Database Analysis.

Objectives: Traditional breast cancer management involves surgery followed by systemic therapies. However, advancements in neoadjuvant chemotherapy (NACT) raise questions about the necessity of surgery in cases with an excellent response to NACT. This study investigates the outcomes of radiotherapy without surgery in selected patients with nonmetastatic breast cancer after a complete or substantial response to NACT.

Methods: A retrospective study was conducted using the SEER database, reviewing records from 2010 to 2020 for patients with nonmetastatic breast cancer who received NACT, associated with a clinical response, followed by radiotherapy alone. The population included 123 patients, stratified into complete clinical response (cCR) and non-cCR (partial or unspecified clinical response) cohorts. Overall survival (OS) and cancer-specific survival (CSS) were analyzed using Kaplan-Meier and Cox proportional hazards models.

Results: The median follow-up was 41 months. Among the patients, 17 (13.82%) achieved cCR. The 5-year OS and CSS for the entire cohort were 65.8% and 71%, respectively, with the cCR group achieving 100% rates for both. Age above 60 and larger tumor size (T3 to T4) were associated with lower OS. The non-cCR group showed a 5-year OS of 61.5% and CSS of 67.1%.

Conclusions: This study indicates that omitting surgery in patients with a cCR to NACT may be feasible, as evidenced by this subgroup's 100% OS and CSS rates at 5 and 10 years. These promising results support further research into less invasive breast cancer management. However, prospective studies must validate these findings and identify suitable patients for nonsurgical approaches.