Descriptive epidemiology of bile duct carcinoma in Osaka

An outbreak of bile duct carcinoma has been reported among workers in a certain printing company in Osaka, Japan, where there was no descriptive epidemiological study. We conducted descriptive studies of bile duct carcinoma in Osaka.

Based on the data from the Osaka Cancer Registry, the incidence and survival rate of intrahepatic and extrahepatic bile duct carcinomas, gallbladder carcinomas and hepatocellular carcinomas were analyzed. The study period was between 1975 and 2007, and total 108 407 incidents were retrieved from the Osaka Cancer Registry. Age- and sex-specific incidence rates and age-standardized incidence rates were calculated. Standardized incidence ratios were evaluated for each municipality in Osaka prefecture. Relative 5-year survival rates were also calculated for the cases diagnosed between 1993 and 2005.

Age-standardized incidence rates of bile duct carcinomas increased distinctly from the middle of the 1970s to the early 1980s in males and the 1990s in females. However, no distinct increase in the incidence rates was observed in 2000. Standardized incidence ratios of those did not exceed the unity significantly in males between 1992 and 2007. In females, standardized incidence ratios exceeded the unity significantly in a few regions without any relation to the location of the printing company where the outbreak was reported. The relative 5-year survival rate is generally poor; however, patients who were diagnosed with localized disease at the age of 25-49 years showed a better survival.

Neither change in trend nor regional accumulation of bile duct carcinoma was confirmed in Osaka, corresponding to the outbreak reported in the printing company.