A proposal to revise the histopathologic grading system of early oral tongue cancer incorporating tumor budding

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>The World Health Organization (WHO) grading system has a low prognostic value for early-stage oral tongue squamous cell carcinoma (OTSCC); greater prognostic power has been shown with tumor budding analysis. In this study, we combined tumor budding analysis with histopathologic grading according to WHO 2017. In our proposal, a revised Grade I tumor is defined as a “well differentiated cohesive tumor”; revised Grade II as a “moderately differentiated and/or slightly dissociated tumor”; and revised Grade III as a “poorly differentiated and/or dissociated tumor”. We evaluated the prognostic value of this proposed grading system in a multicenter cohort of 311 cases of early OTSCC. The proposed grading system showed significant prognostic value in multivariable analysis for disease-specific survival (DSS) with a hazard ratio (HR) of 3.86 and a 95% confidence interval (CI) of 1.36 to 10.9 (<em>P</em> = 0.001). For disease-free survival (DFS), the proposed grading system showed good predictive power in multivariable analysis (HR 2.07, 95% CI 1.00–4.27; <em>P</em> = 0.009). The conventional WHO grading system showed a low prognostic value for DSS and DFS (<em>P</em> > 0.05). In conclusion, the prognostic power of the WHO histopathologic grading improved significantly with incorporation of tumor budding. Our proposed grading system can be easily included in pathology reports.</p></div>