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 as HBV and HCV infections and dioxin exposure between Ho Chi Minh (south) and Hanoi (north). Data for cancer incidence of PLC in Ho Chi Minh (1995-96) and Hanoi (1991-93) were used to calculate rate ratios for the two populations. Published reports on the association between HBV, HCV infections, dioxin (2,3,7,8-TCDD) exposed and HCC in Viet Nam were reviewed. Cancer incidence of PLC was found to be higher in HCM than in Hanoi for males (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 to viral 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 significantly increased for persons who suffered exposure for 10 years or more, OR = 8.8, 95% CI = 1.9-41 independent of HBV infection. Dioxin levels (2,3,7,8-TCDD) in blood samples from people living in the south were more than 2 times higher than in the north (32.6 VS. 15.7 ppt.). Based on the present findings, it is suggested that high incidence of liver cancer in HCM could partly be explained by herbicide exposure.
Ngaon
Le Tran
LT
Department of Clinical Epidemiology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Kitakyushu 807-8555, letngoan@med.uoeh-u.ac.jp ngoantran@hotmail.com
Yoshimura
Takesumi
T