Is the addition of extranodal extension and lymph node yield of pN0 to the lymph node ratio useful as a prognostic parameter for patients with oral squamous cell carcinoma?

We investigated the value of the weighted lymph node ratio (WLNR), a new marker in pN0 patients that incorporates the number of metastatic lymph nodes with extranodal extension and the lymph node yield, for the prognosis and postsurgical management of oral squamous cell carcinoma (OSCC). We designed a retrospective study and enrolled patients with OSCC who were treated by neck dissection (ND). The predictor variable was WLNR, and the outcome variable was overall survival (OS). The Cox proportional-hazards model was used to identify independent prognostic factors. In 133 patients with OSCC, the WLNR cut-off value for predicting OS was 0.0363 (area under the curve 0.723, p<0.001). When stratified according to WLNR, there was a significant difference in OS (88.4% for low WLNR and 63.0% for high WLNR, p<0.001). Univariate analyses showed close associations between OS and age, dissection area, postoperative management, extranodal extension, number of positive lymph nodes, pN stage, WLNR, and nodal disease area. Cox multivariate analysis identified the WLNR as an independent predictive factor for OS (HR 3.273, 95% CI 1.227 to 8.731, p=0.018). As a predictive factor, a high WLNR (≥0.0363) in patients with pN0 disease, which included the addition of extranodal extension and lymph node yield to the LNR, was associated with diminished survival.