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

Abstract

ObjectivesCurrent 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 methodsOncologic 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. ResultsOf 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. ConclusionsPrimary 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.