AIM:To evaluate the effect of hepatitis B virus (HBV) infection on liver metastasis of colorectal cancer.METHODS:A total of 1298 colorectal cancer patients were recruited from January 2001 to March 2005 in this study.Enzyme-linked immunosorbent assay was used to test serum HBV markers for colorectal cancer.Patients were divided into study (infection) group and control (non-infection) group.Clinical features of patients in two groups were compared.RESULTS:Liver metastasis was found in 319 out of the 1298 colorectal cancer patients.The incidence of liver metastasis was significantly lower in study group than in control group (14.2% vs 28.2%,P < 0.01).HBV infection significantly decreased the risk of liver metastasis [hazard ratio (HR):0.50,95% confidence interval (95% CI):0.38-0.66],but the incidence of extrahepatic metastasis was significantly higher in study group than in control group (31.9% vs 17.0%,P < 0.01).The HR was the lowest in chronic hepatitis B group (HR:0.29,95% CI:0.12-0.72).The number of liver metastatic lesions was significantly less in study group than in control group with a higher surgical resection rate.However,no significant difference was found in survival rate between the two groups (P=0.95).CONCLUSION:HBV infection decreases the risk of liver metastasis in patients with colorectal cancer and elevates the surgical resection rate of liver metastatic lesions. AIM: To evaluate the effect of hepatitis B virus (HBV) infection on liver metastasis of colorectal cancer. METHODS: A total of 1298 colorectal cancer patients were recruited from January 2001 to March 2005 in this study. Enzyme-linked immunosorbent assay was used to tests serum HBV markers for colorectal cancer. Patients were divided into study (infection) group and control (non-infection) group. Clinical features of patients in two groups were compared .RESULTS: Liver metastasis was found in 319 out of the 1298 colorectal cancer patients. The incidence of liver metastasis was significantly lower in study group than in control group (14.2% vs 28.2%, P <0.01). HBV infection significantly decreased the risk of liver metastasis [hazard ratio (HR): 0.50,95% confidence interval (95% CI): 0.38-0.66], but the incidence of extrahepatic metastasis was significantly higher in study group than in control group (31.9% vs 17.0%, P <0.01). The HR was the lowest in chronic hepatitis B group (HR: 0.29, 95% CI: 0.12-0.7 2) .The number of liver metastatic lesions was significantly less in study group than in control group with a higher surgical resection rate. However, no significant difference was found in survival rate between the two groups (P = 0.95) .CONCLUSION: HBV infection decreases the risk of liver metastasis in patients with colorectal cancer and elevates the surgical resection rate of liver metastatic lesions.