Tumour thickness and relationship to locoregional failure in cancer of the buccal mucosa.

AIMS: The TNM system is the main parameter in treatment planning and the prediction of survival in oral cancer. Here, we investigate the role of tumour thickness as a predictor of locoregional failure and survival in node-negative patients. METHODS: We studied 176 node-negative and early stage gingivo-buccal squamous cell carcinoma patients retrospectively. Clinico-pathological factors investigated for tumour failure prediction were: T stage; tumour differentiation; tumour thickness; and treatment. Tumour thickness was measured using an ocular micrometer. RESULTS: Locoregional tumour failure was found in 34% of cases (60 of 176). Tumour differentiation was found not to be statistically significant in predicting tumour failure. The covariates predicting tumour failure were T stage (P<0.05); type of surgical treatment (P<0.05); and tumour thickness (P<0.001). The mean tumour thickness found was 4 mm. Tumours 4 mm in thickness behaved similarly in all three stages and those >4 mm had a higher rate of lymph-node metastasis. No distant metastasis was found in this series. CONCLUSION: Tumour thickness was found to be an accurate predictor of locoregional failure in early stage cancer of the buccal mucosa.