Evaluating the efficacy of preoperative radiotherapy in breast cancer patients non-responsive to neoadjuvant chemotherapy: A clinical trial

Introduction: Neoadjuvant chemotherapy (NACT) is a prevalent treatment strategy for patients with locally advanced breast cancer (LABC). Achieving a pathologic complete response (pCR) is a critical determinant of favorable outcomes. To enhance response rates, some clinicians have incorporated radiotherapy (RT) prior to surgery. Methods: This observational cohort study aimed to investigate the initial outcomes and complication rates of preoperative radiotherapy (PRT) in breast cancer (BC) patients who did not achieve a complete response post-NACT. Between January 2017 and January 2020, 216 patients who were clinical T1-3, lymph node-positive, non-metastatic, and received NACT were analyzed. After the final dose of chemotherapy, patients were evaluated clinically and radiologically. Among them, 123 patients were non-complete responders. Of these, 37 patients received PRT according to the guidelines. Results: Following PRT and surgery, 7 (18.9%) patients showed pCR in the breast and 14 (37.8%) in the axilla. HER2-positive and triple-negative breast cancer (TNBC) patients were significantly associated with complete response following PRT in the breast and axilla (p = 0.029). Post-surgical infection was detected in 11 (29.7%) patients, with factors such as a body mass index greater than 25 kg/m2 significantly affecting surgical site infection rates (p = 0.036). The implant loss rate was 16.7% (n = 2), and there was no grade 3 or higher RT-related skin toxicity. Conclusion: This study demonstrated that PRT for non-complete responder patients improves pCR rates in the breast and axilla, allowing almost 38% of patients to have successful breast-conserving surgery, and lowering axillary lymph-node dissection rates without an increase in major complications. Clinical trials: ClinicalTrials.gov: NCT05274594.