Trends in Liver Cancer Incidence between 1985 and 2009, Khon Kaen, Thailand: Cholangiocarcinoma

Background: The Khon Kaen Cancer Registry (KKCR), having both hospital and population-based registration, was established in 1984 at the Faculty of Medicine, Khon Kaen University. Liver cancer is the most frequent malignancy among Thais from northeastern Thailand, but there has hitherto been no assessment of trends over time.
Objective: To perform a statistical assessment of the incidence trends between 1985 and 2009 of liver cancer, specifically focusing on cholangiocarcinoma (CHCA).
Methods: Cases of CHCA, registered between 1985 and 2009, were retrieved from the KKCR and all those with a specific ICD-O-3rd diagnosis with a coding of C22.1, C24.0, C24.8 and C24.9 were selected. Incidence trends were calculated using the generalized linear model method (GLM), which generates incidence rate based logarithms. Jointpoint analysis was used to identify the best fitting model.
Results: Of the 18,589 cases of liver cancer 42% (7,859) were hepatocellular carcinoma and 58% (10,731) were CHCA. Among persons with CHCA, males were affected two times more frequently than females. Three-quarters of the cases were between 55 and 69 years of age. Morphology verified through a cytological or histological examination of tissue from the primary site (%MV) was only 10.8 % (1,141). The respective overall Age Standardized Rate (ASR) for CHCA from 1985 to 2009 was 16.8 to 62.0 per 100,000 among males and 4.8 to 25.6 per 100,000 among females. The respective, overall, ASR of CHCA among males vs. females was 44.3 per 100,000 (95% CI: 38.9 to 49.7) vs. 17.6 (95% CI: 14.5 to 20.7). Among males vs. females, the respective incidence from 1990 to 2009 has been significantly decreasing by –0.7% per year (annual percent change, APC: –0.7%, 95%CI: –2.1% to +0.8%) vs. –0.4% per year (APC: –0.4%, 95% CI: –2.1% to +1.4%).
Conclusions: The rate increase in the first 5 to 6 years may be due to improved completeness of the registry, since in the subsequent 10 to 12 years there is a rather stable rate. It may be, however, that the recent decline in incidence represents a real fall in risk.