Asbestos: a hidden player behind the cholangiocarcinoma increase? Findings from a case–control analysis

PURPOSES: We conducted a case-control analysis to explore the association between occupational exposure to asbestos and cholangiocarcinoma (CC). METHODS: The study was based on historical data from 155 consecutive patients with CC [69 intrahepatic CC (ICC) and 86 extrahepatic CC (ECC)] referred to Sant'Orsola-Malpighi University Hospital between 2006 and 2010. The cases were individually matched by calendar period of birth, sex, and region of residence to historical hospital and population controls. Occupational exposure to asbestos was retrospectively assessed considering job titles obtained from work histories. Separate conditional logistic regression models were applied for ECC and ICC. Estimates were adjusted for smoking status and socioeconomic class. RESULTS: We matched 149 controls (median birth year: 1947; males: 56 %) to 41 cases of ICC (median birth year: 1946; males: 56 %) and 212 controls (median birth year: 1945; males: 48 %) to 59 cases of ECC (median birth year: 1945; males 51 %); 53 cases were not matched due to residence or birth year. We found an increased risk of ICC in workers exposed to asbestos (adjusted OR 4.81, 95 % CI 1.73-13.33); we also observed suggestive evidence that asbestos exposure might be associated with ECC (adjusted OR 2.09, 95 % CI 0.83-5.27). Sensitivity analysis restricted to patients from the Province of Bologna produced confirmatory figures. CONCLUSIONS: Our findings suggest that ICC could be associated with asbestos exposure; a chronic inflammatory pathway is hypothesized. Exposure to asbestos could be one of the determinants of the progressive rise in the incidence of ICC during the last 30 years.