Updated cholangiocarcinoma incidence trends and projections in Thailand by region based on data from four population-based cancer registries

Background Cholangiocarcinoma (CCA) is a significant health concern in Thailand, as the age-standardized rates (ASR) and other trends fluctuate across different regions. However, comprehensive national estimates are lacking. This study examined the Thai ASR of CCA trends from 2012 to 2021 and projected the incidence rates to 2026. Methods This retrospective cohort analysis examined 6379 CCA cases from population-based cancer registries (PBCRs) in the northern, central, northeastern, and southern regions for the time period January 1, 2012, to December 31, 2021. The Joinpoint, age-period-cohort, and Nordpred models were used to assess CCA incidence trends and predictions. Findings CCA incidence trends in Thailand showed a decrease, with an average annual percentage change (AAPC) of -7.20% (95% CI: -11.04 to -3.19) for males, and -5.81% (95% CI: -10.81 to -0.54) for females. The projected incidence rate per 100,000 person-years for 2026 varied slightly according to the model: Joinpoint (males: 6.1, females: 3.4), age-period-cohort (males: 6.0, females: 3.3), and Nordpred (males: 5.5, females: 3.4). Regional analyses revealed decreasing trends in the northern and northeastern regions, with 2026 projections indicating further declines exceeding the 10-year trends. Owing to the small sample size, trends in the central and southern regions could not be determined. Interpretation Thailand's CCA rate has generally decreased but varies geographically; the northern and northeastern regions remain at high risk. To minimize CCA nationally, initiatives should be maintained, new risk factors explored, diagnostics improved, and regional variances addressed. Funding The Graduate School of Khon Kaen University. Copyright (c) 2025 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Health Asia Published https://doi.org/10. 1016/j.lansea.2025. 100569