KRT18 and neoplasm: In comparison with CK18-negative OSCCs, the proportion of CK18-positive tumours was significantly higher among moderately poorly differentiated OSCCs (65.8% vs 92.2%, respectively, P<0.001), patients treated with NACT (45.0% vs 62.2%, respectively, P=0.018), advanced pathological T stage (pT3,4) (58.3% vs 73.3%, respectively, P=0.029), large number (⩾4) of pathologically positive lymph nodes (21.7% vs 44.4%, respectively, P=0.001), and advanced pathological stage (pStage III/IV) (45.0% vs 70.0%, respectively, P=0.0045).