Cholangiocarcinoma and pleural mesothelioma: asbestos exposure as a shared risk factor? A comparison of age-standardized incidence rates in Italy

Abstract

Background and aim. Cholangiocarcinoma (CC) is the second most common primary liver malignancy. Anatomically, CC is divided into intrahepatic (ICC) and extrahepatic (ECC) forms. A possible causal association between ICC and exposure to asbestos has been hypothesized. To support this, we compared age-standardized incidence rates (ASR) of CC and malignant pleural mesothelioma (MPM) in Italy considering that asbestos is thought one of the major risk factors for MPM. Materials and Methods. We extracted ASR of ICC, ECC and MPM reported by 36 Italian cancer registries and listed in the last report on Cancer Incidence in Five Continents of the IARC. Data referred to 2008-2012 and covered 29 million population. We used linear regression analysis to evaluate the possible association between ASR of ICC, ECC and MPM. Analyses were stratified by sex. Results. From 2008 to 2012 ASR per 100,000/years in men ranged: 0.4-2.2 for ICC, 0.5-1.8 for ECC, and 0.0-0.7 for MPM. In women, ASR per 100,000/years ranged: 0.2-1.0 for ICC, 0.1-1.3 for ECC, and 0.0-0.6 for MPM. At regression analysis ICC did not report an association with MPM in men (beta coefficient -0.044, 95%CI -0.980–0.892) and women (beta coefficient -0.093, 95%CI -0.670–0.485). No association was detected for ECC as well. Conclusions. This crude analysis does not appear to support the hypothesis that CC could be associated to exposure to asbestos. This could be related to the large amount of known and suspected risk factors for CC that include common liver diseases due to genes, viruses and personal habits. Analyses adjusted for aggregated data might help disentangle this issue. Keywords: Asbestos, Cholangiocarcinoma, age-standardized incidence rates.