1) Department of Public Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
2) Department of Gastroenterology, Organization of Occupational Health and Safety. Kanto Rosai Hospital, Kanagawa, Japan
ABSTRACT Background: Cholangiocarcinoma is a relatively rare cancer that is difficult to diagnose and has a poor prognosis. Currently, knowledge concerning its etiology, tumor localization, and pathological features remains limited. The present study aimed to clarify the clinico-epidemiologic nature of cholangiocarcinoma with its clinical subtypes using the largest regional cancer registry in Japan. Methods: Using a regional cancer registry in Kanagawa prefecture, Japan, we estimated three-year and five-year survival rates of cholangiocarcinoma patients, who were classified into two groups: intrahepatic (i-CCA) and extrahepatic cholangiocarcinoma (e-CCA) cases. The hazard ratio for each subtype, including pathological tissue type and tumor site, was calculated. Results: During the period from 1976 to 2013, 14,287 cases of cholangiocarcinoma were identified. The prognosis markedly improved after 2006, when a new type of chemotherapy for cholangiocarcinoma was introduced in Japan. Patients with i-CCA were more likely to be younger, and less likely to undergo surgery than those with e-CCA. The prognosis of cases with i-CCA was poor compared to that of patients with e-CCA. Conclusion: In Japan, i-CCA was more likely to develop in younger people and to have a poor prognosis. The prognosis of both i-CCA and e-CCA cases markedly improved after 2006. The present study describes clinico-epidemiological features of cholangiocarcinoma that may be useful for determining therapeutic strategies for this disease. Key words: cholangiocarcinoma – bile duct cancer – epidemiology – survival – adenocarcinoma. Abbreviations: CI : confidence interval; DCO: death-certificate-only; e-CCA: extrahepatic cholangiocarcinoma; i-CCA: intrahepatic cholangiocarcinoma; HR: hazard ratios.