Abstract
In routine pathological diagnoses of oral squamous cell carcinoma （SCC）, histopathological factors such as invasive pattern are assessed to determine the prognosis. In Japan, the Yamamoto–Kohama （YK） classification is generally used. The pattern of infiltrating growth （INF） and tumor budding are recently used as well. Moreover, the AJCC cancer staging manual （8th edition） now lists the worst pattern of invasion （WPOI）-5 as a validated outcome predictor for oral cancer. In this study, we investigated the characteristics of the YK classification, INF, tumor budding, and WPOI-5 with respect to their usefulness as prognostic indicators for pT1/T2 tongue SCC. Three oral pathologists evaluated invasive patterns independently. The individual SCC cases classified as YK-4C, INFc, tumor budding ＞5, or WPOI-5 showed high lymph node metastatic rate and low survival rate, related to increasing risks of poor prognosis. Additionally, the prognoses among these four groups showed no statistical differences, therefore the usefulness of these patterns as prognostic indicators is likely to be equivalent. Cross tabulation indicated that the YK classification, INF, and tumor budding were mutually correlated, and that WPOI-5 might be a histopathological factor that differed from the other three criteria. By simultaneous assessment of these four criteria in each SCC case, we found that most cases met multiple criteria of YK-4C, INFc, tumor budding ＞5, and WPOI-5. Therefore, we concluded that it is effective to apply multiple invasive patterns, specifically the combined use of WPOI-5 and another criterion, to more accurately predict the prognosis of pT1/T2 tongue SCC.
