Prognostic factors of axillary lymph node-positive patients in clinical stage II and III breast cancer after neoadjuvant chemotherapy

Background: Surgery following neoadjuvant chemotherapy (NAC) is increasingly utilized for breast cancer treatment with respect to downstage and recurrent risk reduction. However, there are some uncertainties about the solutions of adjuvant radiotherapy (design of RT field and indication in low-risk patients) in patients after NAC, especially in clinically node-positive patients. The objective of this study is to identify the risk factors of loco-regional recurrence (LRR), relapse and overall survival (OS) regarding tumor response post-NAC in this institution. Methods: From 2007 to 2015, 90 patients with newly diagnosed clinical stage II (n=44) or III (n=46) breast cancer and pathological positive lymph nodes who received chemotherapy followed by breast conserving surgery or mastectomy, adjuvant radiotherapy, and some with adjuvant systemic therapy were identified. All of them received anthracycline-based or taxane-based chemotherapy, external beam radiotherapy and systemic treatment including target or hormone therapy if indicated. Results: After a median follow-up duration of 62 months (7–125 months), the multivariate analysis for risks of LRR showed that the status of clinical lymph nodes (cN2: HR =6.07, P=0.046; cN3: HR =30.22, P=0.001), response subgroups (stable disease: HR =3.01, P=0.047; progressive disease: HR =10.76, P<0.001), and pLNR (67–100%: HR =4.32, P=0.025) have statistical significance. The multivariate analysis for risks of relapse also showed that the status of clinical lymph nodes (cN1 micro/N1: HR =3.97, P=0.037; cN2: HR =4.06, P=0.053; cN3: HR =10.39, P=0.005), response subgroups (progressive disease: HR =3.73, P=0.008) and pLNR (67–100%: HR =3.02, P=0.032) have statistical significance. The multivariate analysis of OS only showed the tumor biomarker status of triple-negative breast cancer (TNBC) (HR =3.04, P=0.048) has statistical significance. Conclusions: In this study, we recorded poor therapeutic response, advanced clinically positive lymph nodes, and higher proportional positivity of dissected lymph nodes showing poor outcome regarding the loco-regional control and relapse-free survival among patients with positive axillary lymph nodes after NAC.