© The Author 2007. Published by Oxford University Press.
Incidence Rates of Intra- and Extrahepatic Cholangiocarcinomas in Denmark From 1978 Through 2002
Affiliations of authors: Department of Clinical Epidemiology (PJ, HTS) and Department of Medicine V (Hepatology and Gastroenterology) (HV), Aarhus University Hospital, Aarhus, Denmark; International Epidemiology Institute, Rockville, MD (RET); Institute of Cancer Epidemiology, The Danish Cancer Society, Copenhagen, Denmark (SF)
Correspondence to: Peter Jepsen, MD, Department of Clinical Epidemiology, Aarhus University Hospital, Ole Worms Allé 1150, DK-8000 Aarhus C, Denmark (e-mail: pj{at}dce.au.dk).
Recent studies from several countries, including the United States, have indicated that the incidence rate of intrahepatic cholangiocarcinoma is increasing while that of extrahepatic cholangiocarcinoma is decreasing. We examined whether such opposing trends could be confirmed in Danish data. We computed the nationwide Danish incidence rates of intra- and extrahepatic cholangiocarcinomas from January 1, 1978, through December 31, 2002, with data from the high-quality Danish Cancer Registry. Incidence rates were standardized to the US population in 2000. The study included 1335 patients with intrahepatic cholangiocarcinoma and 1269 with extrahepatic cholangiocarcinoma. The Danish incidence rates of intra- and extrahepatic cholangiocarcinomas were nearly identical throughout the study period. From 1978 through 2002, the incidence rate of intrahepatic cholangiocarcinoma decreased from 1.27 (95% confidence interval [CI] = 0.96 to 1.58) to 0.46 (95% CI = 0.29 to 0.62) per 100000 people, and the rate of extrahepatic cholangiocarcinoma decreased from 1.05 (95% CI = 0.77 to 1.34) to 0.74 (95% CI = 0.53 to 0.95). The median age at diagnosis decreased during the study period, and the proportion of localized cancers increased. The decrease in cholangiocarcinoma incidence rates cannot be explained by time trends in known risk factors (e.g., inflammatory bowel disease, diabetes, smoking, or thorotrast), but our findings are consistent with a common etiology for intra- and extrahepatic cholangiocarcinomas.
| CONTEXT AND CAVEATS Prior knowledge Data from several countries, including the United States, indicate that the incidence rate of intrahepatic cholangiocarcinoma is increasing while that of extrahepatic cholangiocarcinoma is decreasing. Study design Population-based cancer registry study. Contribution Incidence rates for both cancers in Denmark decreased from 1978 through 2002. Implications Intra- and extrahepatic cholangiocarcinomas may share the same biology. Limitations Only partial information on the prevalence of risk factors for cholangiocarcinoma was available. Misclassification is possible because cholangiocarcinoma topography may have been incorrectly reported.
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Manuscript received November 1, 2006; revised March 19, 2007; accepted March 20, 2007.
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J Natl Cancer Inst 2007 99: 825.