NOVEL ADVANCES IN STAGING AND GRADING OF EARLY ORAL TONGUE CANCER: A MULTICENTER STUDY

Abstract

<h3>Background</h3> Recent research has proposed modifications for the TNM staging and the World Health Organization (WHO) histopathologic grading system of oral cancer. <h3>Objective</h3> (1) To study the significance of different cutoff points of depth of invasion (DOI) in T classification. (2) To study the incorporation of tumor budding to modify the WHO grading system. <h3>Methods</h3> In this multi-institutional study, we included 311 cases treated for early (cT1-2N0M0) oral tongue squamous cell carcinoma at the 5 university hospitals in Finland or at the A.C. Camargo Cancer Centre, São Paulo, Brazil. We suggest using 2 mm DOI to upstage to T2 and 4 mm DOI to upstage to T3. For histopathologic grading, our proposal incorporates tumor budding and defines Grade I as a "well-differentiated cohesive tumor"; grade II as a "moderately differentiated and/or slightly dissociated tumor"; and grade III as a "poorly differentiated and/or dissociated tumor." <h3>Results</h3> There was a significantly improved performance in identification of the high-risk cases for recurrence (hazard ratio [HR] = 2.08; 95% confidence interval [CI], 1.07-4.01; <i>P</i> = .03) and cancer-related mortality (HR = 2.21; 95% CI, 1.05-4.64; <i>P</i> = .036) based on our proposed adjustment of the T stage. Similarly, the proposed histopathologic grade showed worse survival (HR = 3.42; 95% CI, 1.23-9.56; <i>P</i> = .001) and a high rate of recurrence (HR = 1.85; 95% CI, 0.91-3.76; <i>P</i> = .024) for cases having poorly differentiated and/or dissociated tumors. <h3>Conclusions</h3> Our proposed adjustments for staging and grading criteria could improve the risk stratification in early oral tongue squamous cell carcinoma.