Prognostic significance of residual nodal burden using lymph node ratio in locally advanced breast cancer after neoadjuvant chemotherapy.

Abstract

To investigate the prognostic value of lymph node ratio (LNR) after neoadjuvant chemotherapy (NAC) according to breast cancer molecular subtypes. From 2004 to 2014, patients with definitive surgery after NAC were identified. LNR was calculated for node positive patients who underwent axillary dissection and at least 10 nodes (LNT) were removed. Disease free and overall survivals were analysed using Kaplan-Meier test and compared using log rank test for ypN0-3, LNR categories (LNRC) ≤0.2 (low), 0.21-0.65 (intermediate), >0.65 (high), and single LNR cut-off value. Of 224 analysed patients: ypN0 72 (32.1%), ypN+ 152 (67.9%). Of 118 LNT ≥10 ypN+ patients LNRC: Low risk 48 (40.7%), intermediate risk 36 (30.5%), high risk 34 (28.8%). Factors significantly different in LNR categories were ypN (P < 0.001); extranodal extension (P < 0.001); present status of patients (P < 0.001); and disease status (P = 0.029). LNRC was inversely associated with 5-year DFS: Low 52.3%, intermediate 40%, and high 12.2% (log rank P < 0.001); and OS: Low 64.4%, intermediate 58.3%, and high 13.6% (log rank P < 0.001). Significant association of LNRC and DFS and OS were demonstrated in TNBC (P < 0.001) and HER2 subtypes (P = 0.045 and 0.005 respectively). A single value of LNR = 0.25 in node positive was found significant for DFS and OS in TNBC (P < 0.001) and Her2+ (P = 0.013 and P = 0.001 respectively) but not for HR+ (DFS: P = 0.132; OS: P = 0.144). Residual nodal disease after NAC analysed by LNRC or LNR = 0.25 cut-off value, is prognostic and can discriminate between favourable and unfavourable outcomes for TNBC and Her2+ breast cancers.