The Role of Postmastectomy Radiation Therapy for Clinical Stage II-III Breast Cancer Patients With Pathological Complete Remission of Axillary Lymph Nodes After Neoadjuvant Chemotherapy

Abstract

With the increasing use of neoadjuvant chemotherapy (NAC), patients with pathologically involved nodes had a great chance to be found as pathologically node negative at the time of definitive surgery. Several retrospective studies addressed that there were no survival benefits in those patient with pathologically complete remission (pCR) of axillary lymph node who treated with postmastectomy radiotherapy (PMRT) after NAC. We aim to retrospectively evaluate the role of PMRT in clinical stage II-III breast cancer patients with pathological nodes negative (ypN0) after NAC. We retrospectively identified 946 breast cancer patients with clinical stage II-III who underwent NAC in our center between 2003 and 2013. There were 290 patients achieved ypN0 after mastectomy and the clinical outcomes of the patients had been elucidated. The effects of PMRT on locoregional recurrence-free survival (LRRFS), disease-free survival (DFS) and overall survival (OS) were evaluated by Kaplan-Meier method and compared using the log-rank test. Prognostic factors associated with survival were evaluated by univariate and multivariate analysis. The median age was 50 years old (range, 25-80 years). All patients received 2-8 cycles (median, 4 cycles) of preoperative chemotherapy contained with anthracycling and paclitaxel and mastectomy. Of the 290 patients, 217 (74.8%) underwent PMRT and 73 (25.2%) did not. With a median follow-up time of 63 month, 12 patients developed LRR and 39 developed distant metastasis. The 5-year LRRFS, DFS and OS was 94.2%, 79.3% and 91.8% in no-PMRT group and 95.9%, 84.3% and 92.4% in PMRT group, respectively (p=NS). There was no significant difference between the patients with PMRT and without PMRT in terms of survival outcome, even for the subgroup of patients with clinical stage III disease or with residual disease in breast after NAC. On univariate and multivariate analysis, there were no benefits of PMRT on LRRFS (hazard ratio [HR], 0.714; 95% confidence interval [CI], 0.193-2,634; p =0.612), DFS (HR 0.908; 95%[CI], 0.477-1.734; p = 0.773) or OS (HR, 0.829; 95% [CI], 0.291-2.359; p =0.725). Age at diagnosis，ER and LVI status, adjuvant chemotherapy were independent prognostic factors for LRRFS （p＜0.01）, primary tumor response to NAC was marginally significant with poor LRRFS (hazard ratio [HR] 0.109; 95% CI, 0.011-1.098; p=0.06). Advanced Clinical T stage (T3-T4) was independently associated with decreased DFS and OS. Patients who achieved ypN0 after NAC without PMRT had similar outcomes compared with patients treated with PMRT, regardless of clinical stage and primary tumor response. PMRT might not be necessary for ypN0 patients. Prospective randomized study is needed to identify whether it is safe to omit PMRT in patients with clinical stage II-III disease and achieved ypN0 after NAC and mastectomy