Is Lymph Node Ratio a Prognostic Factor for Patients With Oral Squamous Cell Carcinoma?

Abstract

Lymph node ratio (LNR), defined as the ratio of positive resected lymph nodes (LNs) to the total number of resected LNs, predicts survival for some solid tumors. This study investigated the value of LNR in the prognosis and postsurgical management of oral squamous cell carcinoma (OSCC). The authors designed a retrospective cohort study and enrolled a sample of patients who were diagnosed with OSCC and treated by neck dissection. The predictor was LNR and the outcome variable was overall survival (OS). Other variables were dissection type, postsurgical management, number of positive LNs, pN stage, nodal disease area, extracapsular spread, perineural invasion, vascular invasion, and lymph duct invasion. Differences in OS rate were analyzed by log-rank test. A Cox proportional hazards model was used to adjust for the effects of potential confounders. Differences with a P value less than .05 were considered statistically significant. In 95 patients with OSCC, the LNR cutoff value for predicting overall OS was 0.04 (area under the curve, 0.705; P=.010). There was a significant difference in OS when patients were stratified according to LNR (rate for low LNR, 90.5%; rate for high LNR, 68.8%; P=.014). Univariate analyses showed close correlations between OS and LNR, pT stage, number of positive LNs, and nodal disease area (levels IV and V). Cox multivariate analysis identified LNR (hazard ratio [HR]=2.889; 95% confidence interval [CI], 1.032-8.087; P=.043) and area of nodal disease (levels IV and V; HR=5.149; 95% CI, 1.428-18.566; P=.012) as independent predictive factors for OS. OS differed significantly between the high-LNR and low-LNR groups treated by surgery alone (P=.027). As a predictive factor, high LNR (>0.04) was associated with decreased survival, and intensive adjuvant therapy could improve the prognosis for patients with high LNR.