Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012

Background Intrahepatic cholangiocarcinomas (ICCs) and extrahepatic cholangiocarcinomas (ECCs) are highly lethal bile duct tumors. Their incidence can be difficult to estimate because of changes in cancer coding over time. No studies to date have examined their global incidence and trends with high‐quality topography‐ and histology‐specific cancer registry data. Therefore, this study examined ICC and ECC incidence with the Cancer Incidence in Five Continents Plus database. Methods Regional and national cancer registry data were used to estimate age‐standardized incidence rates (ASRs) per 100,000 person‐years, 95% confidence intervals, and average annual percent changes (AAPCs) for ICC in 38 countries and for ECC in 33 countries from 1993 to 2012. ICC and ECC trends were tabulated and plotted by country. Rates versus birth cohort by age were plotted, and an age‐period‐cohort analysis was performed to assess age and cohort incidence rate ratios. Results The highest rates of ICC and ECC were in Asia, specifically South Korea (ASR for ICC, 2.80; ASR for ECC, 2.24), Thailand (ASR for ICC, 2.19; ASR for ECC, 0.71), and Japan (ASR for ICC, 0.95; ASR for ECC, 0.83). Between 1993 and 2012, incidence rates of both ICC and ECC increased in most countries. The largest ASR increases over the study period occurred in Latvia (AAPC, 20.1%) and China (AAPC, 11.1%) for ICC and in Thailand (AAPC, 8.8%) and Colombia (AAPC, 8.5%) for ECC. Conclusions In the 20 years examined, ICC and ECC incidence increased in the majority of countries worldwide. ICC and ECC incidence may continue to increase because of metabolic and infectious etiologic factors. Efforts to further elucidate risk factors contributing to these increases in incidence are warranted.