The Impact of Regional Nodal Irradiation on the Outcomes After Neoadjuvant Chemotherapy in Node Positive Breast Cancer Patients With ypN0: Interim Analysis of a Prospective Randomized Trial.

Abstract

PURPOSE/OBJECTIVE(S)\nTo evaluate the impact of regional nodal irradiation (RNI) on the loco-regional recurrence free survival (LRFS), distant metastases free survival (DMFS) and overall survival (OS) in breast cancer patients with node positive disease who received neoadjuvant chemotherapy (NAC) and became ypN0.\n\n\nMATERIALS/METHODS\nFrom January 1st 2016 till December 31st 2019, 231 patients with node positive breast cancer who received NAC and became ypN0 were randomized to receive whole breast irradiation/post mastectomy irradiation with or without RNI. One hundred and twelve patients were included in the regional nodal irradiation arm (RNI+) and 119 patients were included in the no regional nodal irradiation arm (RNI-).\n\n\nRESULTS\nMedian follow up was 24 months (range, 1-55 months). No regional nodal failures were recorded in both groups. The actuarial LRFS was 98.2% in the RNI+ arm and 100% in the RNI- arm (P 0.28). The actuarial DMFS was 93.6% in the RNI+ arm and 97.4% in the RNI- arm (P 0.93). The actuarial OS was 96.3% in the RNI+ arm and 99.1% in the RNI- arm (P 0.75). Cox univariate regression analysis revealed initial tumor size > 5 cm (HR 1.276, CI 1.054-1.543, P 0.012) was the only factor associated with increased incidence of distant metastases. Age younger than 35 years was associated with worsened survival (HR 0.866, CI 0.760-0.986, P 0.03).\n\n\nCONCLUSION\nIn the current interim analysis, omission of regional nodal irradiation did not compromise the outcomes in clinically node positive patients who received NAC and had ypN0 disease.