OP029: Tumor thickness predicts nodal metastases in Gingivobuccal complex cancers

Abstract

Purpose Cancers of the Gingivobuccal complex (GBC), which comprises of the buccal mucosa, gingivo-buccal sulci and alveolus, are commonly seen in the Indian subcontinent, due to tobacco and betel quid chewing. While tumor thickness is an accepted risk factor for nodal metastases in certain sites of oral cavity, like tongue cancers, its role as a predictor of nodal metastases in GBC cancer is not established. The purpose of this study was: 1. To assess tumor thickness as a predictor of nodal metastases in GBC cancers 2. To find a cut-off value of tumor thickness that would indicate nodal metastases Materials and methods Retrospective analysis of GBC cancers undergoing surgery in our institute from January 2008 to February 2010 was done. Data regarding patient, tumor and nodal factors was documented. Univariate and multivariate analyses were done to find factors predicting nodal metastases. Receiver operated characteristic (ROC) curve was plotted to find cut-off for tumor thickness. Results There were 1058 patients screened, of which 439 were excluded. In 619 eligible patients, 739 neck dissections were performed. Mean tumor thickness was 1.38 cm (range: 0.1–5.5 cm). On univariate analysis, significant predictors of nodal metastases were: gross tumor thickness, primary site, pT stage, and perineural invasion and lymphovascular emboli. On multivariate analysis (logistic regression), tumor thickness was the only significant variable predicting tumor thickness ( p = 0.009). The ROC curve identified 0.45 cm as a reasonable cut off value of tumor thickness that would predict nodal metastases (sensitivity 91%, specificity 86%). Conclusions Gross tumor thickness is a significant determinant of metastatic nodes in GBC cancers. A tumor thickness of 0.45 cm or above in GBC cancers predicts nodal metastases, and this would help guide performing neck dissections in these patients.