Rising incidence of intrahepatic cholangiocarcinoma in the United States: a true increase?

BACKGROUND/AIMS: The incidence of intrahepatic cholangiocarcinoma (ICC) has been reported to be increasing in the USA. The aim of this study is to examine whether this is a true increase or a reflection of improved detection or reclassification.

METHODS

Using data from the Surveillance Epidemiology and End Results (SEER) program, incidence rates for ICC between 1975 and 1999 were calculated. We also calculated the proportions of cases with each tumor stage, microscopically confirmed cases, and the survival rates.

RESULTS

A total of 2864 patients with ICC were identified. The incidence of ICC increased by 165% during the study period. Most of this increase occurred after 1985. There were no significant changes in the proportion of patients with unstaged cancer, localized cancer, microscopic confirmation, or with tumor size <5 cm during the period of the most significant increase. The 1-year survival rate increased significantly from 15.8% in 1975-1979 to 26.3% in 1995-1999, while 5-year survival rate remained essentially the same (2.6 vs. 3.5%).

CONCLUSIONS

The incidence of ICC continues to rise in the USA. The stable proportions over time of patients with early stage disease, unstaged disease, tumor size <5 cm, and microscopic confirmation suggest a true increase of ICC.