Lymph node ratio as an alternative to pN staging for predicting prognosis after neoadjuvant chemotherapy in breast cancer.

Axillary nodal status is one of the most important prognostic factors in breast cancer. The lymph node ratio (LNR) has been suggested as an independent prognostic factor because the number of dissected and involved lymph nodes might differ across institutions. Neoadjuvant chemotherapy (NAC) has been the preferred treatment method for reducing tumor mass in the breast and axillary area. However, NAC can reduce total number of excised lymph nodes compared with upfront surgery. Therefore, an emerging question is whether axillary nodal status and LNR following NAC can accurately predict prognosis. We evaluated the prognostic value of axillary nodal status and LNR after NAC. A total of 236 patients were enrolled. Patients were divided into four groups according to the following cut-off values for LNR: 0 (n = 107), 0.01-0.20 (n = 68), 0.21-0.65 (n = 50) and >0.65 (n = 11). Pathologic complete responses were observed in 16.9% of the overall cohort. In univariate analysis, pathologic N stage was a significant prognostic factor of disease free survival (DFS, p = 0.013) and overall survival (OS, p = 0.004). However, in multivariate analysis, hormone receptor status (p = 0.043) and LNR (p = 0.028) were significantly associated with DFS and LNR (p = 0.017) showed statistical significance for OS; however, pathologic N stage was no longer significantly associated with DFS or OS. Traditional nodal staging has been accepted as an important prognostic factor; however, our result indicated that the nodal ratio could be an alternative to pN staging as a prognostic factor after NAC in breast cancer.