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