Liver Cancer in Viet Nam: Risk Estimates of Viral Infections and Dioxin Exposure in the South and North Populations

Risk factors forPLC due to viral infections and exposure to herbicides have not been available in south Viet Nam.The aim of this study was to clarify geographical differences in cancer incidence of PLC and its risk factors such asHBV and HCV infections and dioxin exposure between Ho Chi Minh (south) and Hanoi (north). Data for cancerincidence of PLC in Ho Chi Minh (1995-96) and Hanoi (1991-93) were used to calculate rate ratios for the twopopulations. Published reports on the association between HBV, HCV infections, dioxin (2,3,7,8-TCDD) exposedand HCC in Viet Nam were reviewed. Cancer incidence of PLC was found to be higher in HCM than in Hanoi formales (RR = 1.22, 95% CI = 1.09-1.36) and in females (RR = 1.21, 95% CI = 0.98-1.49). Risk factors for PLC due toviral infections were seen to be lower in HCM than in Hanoi for patients with HBV infection, (OR = 37.8, 95% CI =11.6-121.4 VS. OR = 61.7, 95% CI = 30.0-128.0) and also for patients with HCV infection and HBsAg (-), (OR = 6.8,95% CI = 2.1-22.1 VS. OR = 38.1, 95% CI = 2.8-1443.0). The risk of PLC due to exposure to herbicides was significantlyincreased for persons who suffered exposure for 10 years or more , OR = 8.8, 95% CI = 1.9-41 independent of HBVinfection. Dioxin levels (2,3,7,8-TCDD) in blood samples from people living in the south were more than 2 timeshigher than in the north (32.6 VS. 15.7 ppt.). Based on the present findings, it is suggested that high incidence of livercancer in HCM could partly be explained by herbicide exposure.