Serum levels of IQGAP3, B7-H4, COX-2, CEA and CA19-9 in CRC group were significantly higher than those in control group (IQGAP3: 312.68 ± 101.91 vs. 191.97 ± 103.96, P < 0.001; B7-H4: 97.85 ± 15.56 vs. 64.78 ± 16.73, P = 0.003; COX-2: 48.55 ± 13.43 vs. 25.78 ± 16.09, P < 0.001; CEA: 6.62 ± 4.49 vs. 3.41 ± 1.27, P < 0.001; CA19-9: 29.92 ± 8.97 vs. 19.24 ± 10.08, P < 0.001). The gene discussed is PTGS2; the disease is colorectal carcinoma.