Prognostic value of the sixth edition of the UICC's TNM classification and stage grouping for oral cancer

Abstract

Carcinoma of the oral cavity is classified according to the TNM staging system of the UICC. The staging system is under continuous revision. The aim of our study was to assess the prognostic value of the UICC sixth edition for oral cancer, which was established in 2003. Three-hundred treatment-naive patients with oral squamous cell carcinoma (OSCC) of stages I-IVb were reviewed retrospectively. Patients with stage-I disease were treated solely surgically, and patients with stage II-IVb received a multimodal treatment. Overall survival was plotted by Kaplan-Meier analysis. Prognostic factors were identified through univariate and multivariate analysis. Univariate analysis showed a significant impact of T stage (P = 0.009), N stage (P < 0.001), and UICC stage (P < 0.001) on overall survival. However, no statistical differences were observed between stages T4a and T4b (P = 0.176) and UICC stages IVa and IVb (P = 0.306). T stage, N stage, and UICC stage grouping are good predictors of overall survival in patients with OSCC. Neither the division of stage T4 into T4a and T4b in the sixth edition nor the split of stage IV into IVa and IVb showed significant differences in overall survival between the subgroups.