The significant differences were shown in serum Cyfra21-1 (P = 0.003), Pro-SFTPB (P = 0.003), NSE (P = 0.001), SCC (P = 0.004), and Pro-GRP (P = 0.008) levels among the LADC and SCLC. Here, ENO2 is linked to small cell lung carcinoma.