Number of positive lymph nodes better predicts survival for oral cavity cancer.

Abstract

We compared the predictive ability of our proposed N classification with that of the American Joint Committee on Cancer (AJCC) nodal (N) classification for oral cavity squamous cell carcinoma (OCC). We assessed 345 OCC patients who underwent primary tumor extirpation and neck lymph node (LN) dissection. N classification was analyzed by recursive partitioning analysis and compared with the AJCC N classification by c-index. Cox proportional hazards regression analyses were used to determine associations between tumor or nodal factors and disease-free survival (DFS) or overall survival (OS). Positive LNs were found in 149 patients (43.2%). In multivariate models, the number of positive LNs and LN ratio strongly associated with DFS and OS (P < 0.001). Our new N classification was proposed with four categories of N0, N1 (1 positive LN), N2 (2-4 positive LNs or extranodal extension > 2 mm), and N3 (≥5 positive LNs). The c-index for the proposed N classification showed improvement in survival predictions (0.735; 95% CI, 0.703-0.767) compared with the AJCC N classification (0.701; 0.667-0.735). The number of positive LNs and LN ratios strongly associated with posttreatment recurrence and survival for OCC. Using positive LN numbers with the N classification improves OCC survival predictions.