Secular trends of intrahepatic cholangiocarcinoma in a high endemic area: A population-based study.

Background: Intrahepatic cholangiocarcinoma (ICC) is one of the most aggressive malignancies. However, because of its scarcity there are limited population-based data available for investigations into its epidemiologic characteristics. In Taiwan, we have a national cancer registry database that can be used to evaluate the secular trends of ICC.

Aim: To evaluate secular trends of ICC according to age, sex, and risk factors in Taiwan.

Methods: In this population-based study, we used the national Taiwan Cancer Registry database. Age-standardized and relative percent changes in incidence rates were used to describe secular trends in incidence rates and sex ratios of ICC in Taiwan.

Results: The age-standardized ICC incidence rate among males increased from 1.51 per 100000 in 1993-1997 to 4.07 per 100000 in 2013-2017 and among female from 1.73 per 100000 to 2.95 per 100000. The incidence in females tended to plateau after 2008-2012. For males, the ICC incidence increased as age increased. In the long-term incidence trend of ICC in females, the incidence of the four age groups (40-44, 45-49, 50-54 and 55-59 years) remained stable in different years; although, the incidence of the 60-64 group had a peak in 2003-2007, and the peak incidence of the 65-69 and 70-74 groups occurred in 2008-2012. Among males, beginning at the age of 65, there were increases in the incidence of ICC for the period of 2003-2017 as compared with females in the period of 2003-2017.

Conclusion: Increased incidence of ICC occurred in Taiwan over the past two decades. The increased incidence has progressively shifted toward younger people for both males and females.