The expression of key genes was verified in HCC and normal tissues, and the expression of CXCL5 (P = 0.013), IL18RAP (P = 0.002), and TREM2 (P < 0.001) was determined to be higher in tumor tissues than in normal tissues; however, no differences were observed in CXCL8 expression (Figure 12(a)). The gene discussed is TREM2; the disease is hepatocellular carcinoma.