MKI67 and small cell lung carcinoma: In our Ki-67-Average evaluation the optimal cut-off value to distinguish TC from AC is 1.5% (AUC = 0.870, p < 0.001, sensitivity = 0.810, 1-specificity = 0.167), AC from SCLC 19.0% (AUC = 0.998, p < 0.001, sensitivity = 0.960, 1-specificity = 0.000) and AC from LCENC 23.5% (AUC = 1.000, p < 0.001, sensitivity = 1.000, 1-specificity = 0.000).