Risk factors for cholangiocarcinoma: A case-control study

The primary aim of this study is to measure the independent association between cholangiocarcinoma and the use of alcoholic beverages. Secondarily, tobacco use, Opisthorchis viverrini infestation, use of praziquantel, and intake of various food groups and nutrients were evaluated as potential risk factors. Two hundred incident cases of cholangiocarcinoma, aged 31--80 and residents of Khon Kaen province, were identified by reviewing medical records from Khon Kaen University hospital and Khon Kaen hospital. Population controls, frequency-matched to cases on age and gender, were identified through random sampling the Khon Kaen population registry. Exposure information was obtained through face-to-face interview, a food frequency questionnaire, and a blood sample. Response rates for cases and controls were 99% and 98% respectively. The odds ratio (OR) for current alcohol drinkers relative to noncurrent drinkers and adjusted for age, gender, education, household income, tobacco use, opisthorchiasis, use of praziquantel, vitamins A & C, and total energy intake was 1.51 (95% CI, 0.78--2.9). The risk of cholangiocarcinoma did not increase with the number of drinks consumed. Adjusted OR for current smokers, relative to ex- or non-smokers was 1.49 (95% CI, 0.83--2.69). Adjusted OR point estimates increased with the number of pack-year equivalents of smoking for current smokers, but the trend was not statistically significant (p for trend = 0.13). Adjusted OR for individuals with an increase in titer of antibodies to O. viverrini was 6.8 (95% CI, 3.31--13.9). Adjusted OR point estimates increased with increasing number of praziquantel use (p for trend = 0.0001). Consumption of fruits and vegetables (p for trend < 0.0001) and fish (p for trend = 0.0003) was associated with a statistically significant dose-dependent reduction in risk for cholangiocarcinoma. Consumption of cereals and bread (p for trend < 0.0001), meat (p for trend = 0.0005), dairy products (p for trend < 0.0001), and nitrite-containing foods (p for trend = 0.004) was statistically significant dose dependent increase in risk of cholangiocarcinoma. Total dietary vitamin A (p for trend < 0.0001), dietary carotene (p for trend < 0.0001), and dietary vitamin C (p for trend = 0.002) were statistically significant associated with cholangiocarcinoma risk reduction.