Risk factors of cholangiocarcinoma in areas not endemic for liver fluke infection.

Background: Thailand has the world's highest prevalence of cholangiocarcinoma (CCA), especially in the endemic area of liver fluke infection. However, other regions of Thailand still have relatively high CCA prevalence.

Objectives: We aimed to determine CCA risk factors in areas not endemic for OV infection.

Methods: A case--control study was performed at a referral center during December 2016-December 2017. We collected blood samples and information from CCA patients and identified them as cases. The control group comprised patients who visited a gastrointestinal clinic for colorectal cancer screening colonoscopy. Logistic regression analysis was used to determine risk factors for CCA.

Results: Of 138 participants, infection rate was higher in the case than in the control group (57.1% vs. 36.1%, = 0.023). Male, infection, smoking, alcohol consumption, and biliary tract diseases were independent risk factors, whereas diabetes, obesity, and cirrhosis were not associated with CCA. By age and sex-adjusted analysis, chronic biliary tract diseases, especially choledochal cysts and smoking, were risk factors for CCA, with adjusted odds ratio (aOR) of 12.7 (95% confidence interval [CI]: 1.4-116.9) and 3.8 (95% CI: 1.3-11.8), respectively, while infection became insignificant risk for CCA (aOR 1.8, 95% CI: 0.8-4.1).

Conclusions: In contrast with endemic areas for infection, chronic biliary tract diseases and smoking are major risk factors, whereas infection has trivial contribution to the development of CCA.