Table 1.

Cohort and case-control studies investigating occupational asbestos exposure and iCCA risk.

TYPE OF STUDY	NO OF SUBJECTS	WORKERS’ CATEGORY	YEARS	ASBESTOS EXPOSURE ASSESSMENT	CANCER SITE	EFFECT MEASURES
Cohort[10]	• 4427 workers • 22135 matched controls	Shipbreaking workers	1975–1989	A panel of seven experts was asked to assess exposure subjectively	Liver and Intrahepatic bile ducts	HRadj 1.6 (95% CI 1.08-2.36)
Cohort [11]	12578 workers	Asbestos-cement workers	1934–2006	Two expert industrial hygienists estimated asbestos exposure based on already collected data, for each plant and period	Liver and Intrahepatic bile ducts	SMR 0.99 (95% CI 0.81–1.20) (Males) SMR 0.87 (95% CI 0.42–1.60) (Females)
Case-control [12]	• 41 iCCA cases • 149 controls	All the different occupations of cases and controls were considered	2006–2010	Based on detailed entire job history and calendar periods, assessment of past asbestos exposure (Yes/No) was performed independently by two Occupational Physicians, unaware of case/control status	Intrahepatic bile ducts	Occupational exposed to asbestos vs not exposed ORadj 4.81 (95% CI 1.73–13.33)
Case-control [13]	• 1458 iCCA cases • 6773 controls	All the different occupations of cases and controls were considered	1971–2005	The exposure to asbestos for each subject was estimated by applying the NOCCA job-exposure matrix (JEM) to the available occupational codes of cases and controls	Intrahepatic bile ducts	Cumulative exposure 1.0 (reference):0 f/mL × years OR adj 1.1 (95% CI 0.9-1.3): 0.1–4.9 f/mL × years OR adj 1.3 (95% CI 0.9-2.1): 5.0–9.9 f/mL × years OR adj 1.6 (95% CI 1.0-2.5): 10.0–14.9 f/mL × years OR adj 1.7 (95% CI 1.1-2.6): ≥15.0 f/mL × years

^a Estimates from logistic regression models conditioned on matching variables (year of birth, gender and country). Abbreviations: HR_adj: adjusted hazard ratio; SMR: standardized mortality ratio; OR_adj: adjusted Odds ratio; f/mL: fibers/mL; NOCCA: Nordic Occupational Cancer Study.