Exposure to chlorinated solvents and lung cancer: results of the ICARE study

Our plain-English summary of Exposure to chlorinated solvents and lung cancer: results of the ICARE study, by F. Mattei, F. Guida, M. Matrat, et al (Occupational and Environmental Medicine, 2014).

The study

• Authors: F. Mattei, F. Guida, M. Matrat, S. Cenée, D. Cyr, M. Sanchez, L. Radoi, G. Menvielle, F. Jellouli, M. Carton, S. Bara, E. Marrer, D. Luce, I. Stücker
• Journal: Occupational and Environmental Medicine
• Published: 2014;71(10):681-9
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To investigate the role of occupational exposure to chlorinated solvents in lung cancer aetiology.

Methods: ICARE (Investigation of occupational and environmental CAuses of REspiratory cancers) is a French, multicentre, population-based, case-control study. Information on the lifelong work history of 2926 cases and 3555 controls was collected using standardised questionnaires. Occupational exposures were assessed using job-exposure matrices for five chlorinated solvents. Solvents were studied separately and in combinations. ORs were computed using unconditional logistic regression models adjusted for classic risk factors, including a history of cigarette smoking and exposure to asbestos. Adjustment for socioeconomic status (SES) was also made.

Results: After adjustment for exposure to asbestos, we observed a positive, statistically significant association with lung cancer for men and women exposed to a combination of perchloroethylene (PCE), trichloroethylene and dichloromethane (DCM). Further adjustment for SES slightly decreased this association. In contrast, no statistically significant associations were found for other solvent combinations.

Conclusions: These results suggest that exposure to PCE may constitute a risk factor for lung cancer, especially among women, who seem to have a higher prevalence of exposure than men.

Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

In plain English

This French population-based case-control study (ICARE, 2001 to 2007) compared 2926 people with lung cancer and 3555 controls. Job histories and job-exposure matrices were used to estimate exposure to five chlorinated solvents, including trichloroethylene (TCE), perchloroethylene (PCE) and dichloromethane (DCM). Analyses were adjusted for smoking and occupational asbestos exposure, and in further models for socioeconomic status. For TCE, no association was found after asbestos adjustment in men, or in men and women never exposed to asbestos. In women, asbestos-adjusted results were weakly positive, with an odds ratio of 1.93 (95% CI 1.08 to 3.45) in the higher cumulative-exposure group. After asbestos adjustment, women ever exposed to PCE had an odds ratio of 3.02 (95% CI 1.37 to 6.64); for men the figure was borderline. For combined TCE, DCM and PCE exposure, the fully adjusted odds ratio was 4.57 (1.14 to 18.34) in women and 1.28 (0.83 to 1.98) in men. Men's TCE jobs were mainly in metal work, which also involves asbestos. The authors concluded that PCE alone or combined with other solvents may increase lung cancer risk. They noted that few women were exposed and called for replication.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Multicentre, population-based case-control study (analysis of the ICARE study)
• Who was studied: 2926 lung cancer cases (2276 men, 650 women) and 3555 population controls (2780 men, 775 women), aged 18 to 75, in 10 French administrative departments, 2001 to 2007
• Exposure: Occupational exposure to five chlorinated solvents: trichloroethylene (TCE), dichloromethane (DCM), perchloroethylene (PCE), chloroform (CF) and carbon tetrachloride (CT), assessed with job-exposure matrices. Occupational asbestos exposure (cumulative index in quartiles) was adjusted for as a confounder.
• Main results:
  • Among controls, lifetime exposure to any chlorinated solvent was 8.5% for men and 2.1% for women.
  • Among men, positive associations for TCE, DCM and PCE disappeared after adjustment for asbestos exposure, except for PCE. The ever-exposed OR for PCE in men was borderline significant (OR=1.41, 95% CI 0.98 to 2.05).
  • Among women, borderline significant positive associations were found for TCE, PCE and DCM, and dose-response relationships remained after adjustment for asbestos and socioeconomic status.
  • Among women, TCE exposure in the higher cumulative-exposure category, adjusted for asbestos (Table 2), had an OR of 1.93 (95% CI 1.08 to 3.45), with a trend p value of 0.023.
  • Among women, ever exposure to PCE, adjusted for asbestos (Table 2), had an OR of 3.02 (95% CI 1.37 to 6.64). With further adjustment for socioeconomic status the OR was 2.74 (95% CI 1.23 to 6.09).
  • For TCE, no association was found among subjects never exposed to asbestos. Men: 40 cases and 69 controls exposed, OR=1.01, 95% CI 0.62 to 1.67. Women: 17 cases and 16 controls exposed, OR=0.88, 95% CI 0.40 to 1.96.
  • Before asbestos adjustment, people exposed to the combination of TCE, DCM and PCE had ORs of 1.81 (95% CI 1.18 to 2.76) for men and 5.39 (95% CI 1.37 to 21.16) for women.
  • For the TCE, DCM and PCE combination, the ORs after asbestos adjustment were 5.16 (95% CI 1.30 to 20.54) in women and 1.45 (95% CI 0.94 to 2.24) in men. With further socioeconomic adjustment they were 4.57 (95% CI 1.14 to 18.34) in women and 1.28 (95% CI 0.83 to 1.98) in men.
  • Self-reported PCE exposure: men (17 cases, 11 controls) had OR=3.25, 95% CI 1.23 to 8.59; women (5 cases, 2 controls) had OR=3.12, 95% CI 0.50 to 19.28. Adjusting for asbestos did not affect these results.
  • Men exposed to TCE worked mainly in metal-work jobs that also involve asbestos.
  • PCE jobs were mainly laundry and dry-cleaning for women and printing for men, which the authors described as unlikely to involve asbestos exposure.
• The authors' conclusion: The authors concluded that PCE alone or in combination with other solvents may increase the risk of lung cancer, and stated that their findings did not suggest an association between TCE and lung cancer.
• Limitations the authors state:
  • Exposure misclassification is possible, which could bias results toward no association.
  • Far fewer women than men were exposed, giving wide confidence intervals.
  • The effect of PCE alone could not be assessed, because almost all PCE-exposed subjects were also exposed to other solvents.
  • Except for TCE, analyses limited to people never exposed to asbestos had numbers too small for precise estimates.
  • Confounding by socioeconomic status cannot be excluded, even after adjusting for smoking and asbestos.
  • The large number of analyses raises concern about multiple testing.
  • The results need to be replicated in a larger exposed population.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Occupational Exposure, Case-Control Study, Occupational History.

Related studies

• Multidimensional analysis of the effect of occupational exposure to organic solvents on lung cancer risk: the ICARE study — F. Mattei, S. Liverani, et al. (2016)
• Occupational exposure to chlorinated solvents and risk of head and neck cancer in men: a population-based case-control study in France — C. Barul, A. Fayossé, et al. (2017)
• Occupational exposure to textile dust and lung cancer risk: Results from the ICARE Study — S. Ben Khedher, M. Neri, et al. (2018)
• Case-control study on renal cell cancer and occupational exposure to trichloroethylene. Part I: Exposure assessment — J. Fevotte, B. Charbotel, et al. (2006)
• Risk of lung cancer associated with occupational exposure to mineral wools: updating knowledge from a french population-based case-control study, the ICARE study — F. Guida, S. Paget-Bailly, et al. (2013)
• The joint effect of asbestos exposure, tobacco smoking and alcohol drinking on laryngeal cancer risk: evidence from the French population-based case-control study, ICARE — G. Menvielle, A. Fayossé, et al. (2016)

Browse more research in Occupational and Environmental Medicine, or return to medical research.