Resected SCLC samples were grouped by a positive or negative result for ASCL1, NEUROD1, YAP1, and POU2F3, and differences in the expression of the candidate target molecules were compared between the ASCL1-positive and ASCL1-negative groups, NEUROD1-positive and NEUROD1-negative groups, YAP1-positive and YAP1-negative groups, and POU2F3-positive and POU2F3-negative groups. Here, POU2F3 is linked to small cell lung carcinoma.