Differences in the Environmental Exposure Pattern Between Peritoneal and Pleural Mesothelioma: Data From the Mesothelioma Lombardy Region Register (Italy)

Abstract

O-30B8-2 Background/Aims: The attributable risk to asbestos exposure (occupational and/or environmental) is somehow different in pleural (PLM) and peritoneal malignant mesothelioma (PEM), with some recent studies suggesting a more limited role of occupational asbestos exposure in the etiology of PEM. A population-based registry of mesothelioma cases has been established in the Lombardy, Italy, since 2000. We compared exposure history and the main characteristics of PEM and PLM cases diagnosed in the period 2000–2007. Methods: We selected all incident cases in subject residing in Lombardy (period 2000–2007 for PEM, n = 110 and period 2000–2001, n = 515 for PLM). All cases were investigated by an Expert Panel which evaluated clinical records, occupational and residential history, and lifestyle. Differences between PLM and PEM cases were investigated using Fisher exact test. Results: The proportions of cases with occupational or environmental/familial exposures were similar between PEM and PLM cases (50% occupational and 6% environmental), instead the prevalence of subjects with both occupational and environmental/familial exposure was more than doubled among PEM cases (6.4% vs. 2.7%, P = 0.059). PEM cases showed a higher proportion of females (48% vs. 36%) and a higher proportion of subjects with asbestosis and with pleural plaques at the CT scan. No significant differences between PEM and PLM cases were observed regarding age at diagnosis, smoking habits, and level of diagnostic certainty. Conclusion: Our data suggest that asbestos exposure is the main risk factor not only for PLM but also for PEM, and pointed out the importance of mixed occupational and environmental exposure in etiological pathway leading to such a rare but fatal disease, encouraging any efforts to identify unknown sources of exposure in order to ensure public health.