Prognostic determinants of locally advanced buccal mucosa cancer: Do we need to relook the current staging criteria?

OBJECTIVES: Current guidelines advocate non-surgical treatment for T4b buccal mucosa carcinoma with surgery preferred in other stages. We investigated oncologic outcomes of this cohort in comparison with T4a cohort, treated by similar multi-modality approach of primary surgery followed by adjuvant treatment and identified prognostic determinants of survival.

MATERIALS AND METHODS: Oncologic outcome of prospectively accrued 282 patients with cT4a and cT4b buccal mucosa squamous cell carcinoma were evaluated for overall survival (OS) and disease free survival (DFS) at 2 years of the whole cohort and for the subgroups of T4a and T4b patients. Multivariate Cox proportional hazards regression analysis was performed to identify prognostic determinants.

RESULTS: Of 277 eligible patients treated and followed for a median period of 21 months, the OS was comparable between T4a and T4b as 64% vs 58%, (p = 0.354). The DFS between the two subgroups was 64% vs 61%, (p = 0.316). Although there was 47% pathologic down staging from the clinical stage, there was no significant difference in oncologic outcome between pT4a and pT4b (OS, 57% vs 58% for T4a and T4b, p = 0.687; DFS, 58% vs 60% for T4a and T4b, p = 0.776). On multivariate analysis, extra capsular spread (p = 0.042), lateral pterygoid muscle involvement (p = 0.035) and defaulting adjuvant treatment (p < 0.001) were independent predictors of outcome for the T4b cohort when other factors were controlled.

CONCLUSIONS: Primary surgery followed by adjuvant chemo-radiotherapy offers comparable results in selected T4b gingiva and buccal mucosal cancer, suggesting the need to relook the staging criteria for oral cavity cancer.