Comparison of tumor volume, thickness, and T classification as predictors of outcomes in surgically treated squamous cell carcinoma of the oral tongue.

Abstract

As per TNM classification, superficial tumors with a favorable prognosis are fallaciously clubbed together with unfavorable, deeply infiltrating lesions in the same classification. This is a retrospective study of 588 patients with treatment-naive oral tongue cancers. Binary logistic regression was used to identify predictors of nodal metastasis and extracapsular spread (ECS) using tumor volume and thickness as separate models. The C-index was generated to quantify predictive accuracy of T classification, thickness, and tumor volume for survival. Compared to T classification, tumor volume and thickness were better predictors of nodal metastasis and ECS. Predictive accuracy for disease-free survival (DFS) and overall survival (OS) given by C-index was equal and better for thickness (0.60 and 0.69) and tumor volume (0.61 and 0.69) as compared to T classification (0.59 and 0.64, respectively). For early-stage T1 to T2 oral tongue cancer, thickness is a better predictor of nodal metastasis as compared to tumor volume and T classification. Concordance between the tumor thickness and volume proves that tumor thickness can be taken as a surrogate and reliable predictor of outcomes instead of calculating the tumor volume.