Peritoneal mesothelioma and asbestos exposure: a population-based case–control study in Italy, 2000–2021

Objectives Using a case-control design, we examined the association between occupational asbestos exposure and risk of peritoneal mesothelioma in the general population in Italy.Methods From the National Mesothelioma Registry, we selected cases (2000-2021) with life-time occupational history. Controls were 3045 from three case-control studies (region-sex-age-matched, performed in six regions), one in 2002-2004 (2116 population controls) and two in 2012-2016 (718 population and 211 hospital controls). For all subjects, exposure assignment was based on a quantitative job-exposure matrix (SYN-JEM). Qualitative expert-based evaluation was available for all cases, but only in 2012-2016 for 929 controls. We estimated ORs and 90% CIs using logistic regression models adjusted for residence, gender, period and age.Results In complete analyses (1591 cases, all years/regions), the OR for ever exposure was 3.66 (CI 3.21 to 4.18, 45.4% cases and 27.8% controls exposed). Among the exposed, median cumulative exposure (fibres/mL-years) was 1.4 (max 20.0) in cases and 1.1 (max 10.9) in controls. The OR was 1.55 (1.48 to 1.62) per log10-transformed cumulative exposure. In analyses restricted to 290 cases (same years/regions of controls), ORs were 3.35 (2.57 to 4.37, 43.8% cases exposed) for ever exposure and 1.52 (1.39 to 1.65) for cumulative exposure. ORs for ever asbestos exposure using expert-based evaluation were particularly high, 4.32 (3.50 to 5.34, 53.9% cases and 26.4% controls exposed) in complete analyses (778 cases) and 6.35 (4.58 to 8.81, 57.1% cases exposed) in restricted analyses (245 cases), but are known to be more prone to bias.Conclusions Peritoneal mesothelioma showed clear associations with asbestos exposure using different exposure assessment methods.