Abstract

Background: Cholangiocarcinoma (CCA) caused by Opisthorchis viverrini is a well-known and significant public health issue in northeastern Thailand; however, pesticide exposure (PE) and CCA risk have not yet been established. Therefore, our research objective was to investigate the relationship between PE and CCA risk.

Methods: A hospital-based matched case-control study was carried out. All cases (in-patients) and controls (out-patients) were volunteers at a tertiary hospital in northeast Thailand. Between 2015 and 2019, 178 incident cases of pathologically-confirmed CCA and 356 controls were selected from the check-up clinic at Srinagarind Hospital outpatient database (two controls per case). The recruited controls were individually matched to the CCA cases based on sex, age (±5 years), and admission date (±3 months). During face-to-face interviews, a standardised pre-tested questionnaire was used to collect data. Multivariable conditional logistic regression was used to analyse the data.

Results: The respective frequency of PE between the 178 CCA cases and 356 controls was 77.0% vs. 87.6% for never, 14.6% vs. 5.3% for have but stopped, and 8.4% vs. 7.0% for current users. After adjusting for the highest educational attainment, smoking behaviour, alcohol use, and history of cancer in the family, PE was not significantly associated with CCA (p-value = 0.086). Using volunteers who have never used PE as the reference group, the respective odds of developing CCA for those who have ever used but have since stopped and currently using was 2.04 (adjusted OR = 2.04; 95 % CI: 1.03 – 4.04) vs. 0.83 (adjusted OR=0.83; 95% CI: 0.39 – 1.76) times more likely to develop CCA than those who had never used PE.

Conclusion: There is no association between PE and the risk of CCA. Future research should focus on enhancing PE assessment methods that consider complex chemical mixtures, chemicals of interest, historical exposure, and exposure pathways. In addition, it emphasised the need for more extensive and longer population-based cohort studies that include younger, non-occupationally exposed individuals during periods of developmental susceptibility.