Additional prognostic value of lymph node ratio over pN staging in different breast cancer subtypes based on the results of 1,656 patients.

ABSTRACT

PURPOSE: Although the impact of lymph node ratio (LNR ratio of metastatic to resected LNs) in breast cancer (BC) has been investigated, its prognostic value in molecular subtypes remains unclear. Our aim was to evaluate the impact of LNR compared to pN-stage in BC subtypes. PATIENTS/METHODS: We analyzed the impact of LNR and pN-stage on disease-free (DFS) and overall survival (OS) in 1,656 patients with primary BC who underwent primary axillary surgery (removal of ≥10 LNs) between 1998 and 2011. The cut-off points for LNR were previously published. Using immunohistochemical parameters tumors were grouped in luminalA, luminalB/HER2-, luminalB/HER2+, HER2+ and triple negative (TNBC). RESULTS: For the entire cohort 5/10-year DFS and OS rates were 88/77% and 88/75%, respectively. LNR and pN-stage were independent prognostic parameters for DFS/OS in multivariate analysis in the entire cohort and each molecular subgroup (p < 0.001). However, increasing LNR seemed to discriminated 10-year DFS slightly better than pN-stage in luminalA (intermediate/high LNR 65/44% versus pN2/pN3 71/53%), luminalB/HER2- (intermediate/high LNR 48/24% versus pN2/pN3 41/42%), and TNBC patients (intermediate/high LNR 49/24% versus pN2/pN3 56/33%). CONCLUSIONS: LNR is an important prognostic parameter for DFS/OS and might provide potentially more information than pN-stage in different molecular subtypes.