Infection with Opisthorchis viverrini (OV) is associated with cholangiocarcinoma. OV is common in northeast Thailand, but less than 10% of the inhabitants develop cholangiocarcinoma. Animal experiments suggest that OV infection alone does not cause cholangiocarcinoma, and thus other environmental and genetic factors may play a role in causation. We conducted a population‐based case‐control study in which sex, age and place of residence were matched individually. Polymorphisms of GSTM1 and GSTT1 alone were not associated with risk for cholangiocarcinoma, while an elevated level of antibodies against OV (ELISA) ≥0.200 was the strongest risk indicator (odds ratio as compared to that <0.200 = 27.09 [95% confidence interval (CI): 6.30–116.57]. Compared to subjects who had a normal antibody range and the wild‐type GSTM1 gene, those who had elevated antibodies had higher odds ratios of 12.32 (95% CI: 1.60–94.85) for wild‐type GSTM1 and 23.53 (95% CI: 4.25–130.31) for the null variant thereof, respectively. Past and current regular drinkers of alcohol had higher risk [odds ratio = 5.39 (95% CI: 1.11–26.06) and 4.82 (95% CI: 1.29–18.06), respectively]. Eating fermented products was an independent risk factor. Smokers or consumers of fermented fish had substantially increased risk if they were past or current drinkers. Infection with OV correlates strongly with cholangiocarcinoma, susceptibility to which may be possibly associated with GSTM1 polymorphism. Alcohol may affect metabolic pathways of endogenous and exogenous nitrosamines.

In Thailand, five cancer types—breast, cervical, colorectal, liver and lung cancer—contribute to over half of the cancer burden. The magnitude of these cancers must be quantified over time to assess previous health policies and highlight future trajectories for targeted prevention efforts. We provide a comprehensive assessment of these five cancers nationally and subnationally, with trend analysis, projections, and number of cases expected for the year 2025 using cancer registry data. We found that breast (average annual percent change (AAPC): 3.1%) and colorectal cancer (female AAPC: 3.3%, male AAPC: 4.1%) are increasing while cervical cancer (AAPC: −4.4%) is decreasing nationwide. However, liver and lung cancers exhibit disproportionately higher burdens in the northeast and north regions, respectively. Lung cancer increased significantly in northeastern and southern women, despite low smoking rates. Liver cancers are expected to increase in the northern males and females. Liver cancer increased in the south, despite the absence of the liver fluke, a known factor, in this region. Our findings are presented in the context of health policy, population dynamics and serve to provide evidence for future prevention strategies. Our subnational estimates provide a basis for understanding variations in region-specific risk factor profiles that contribute to incidence trends over time.