Occupational asbestos exposure and risk of pleural mesothelioma, lung cancer, and laryngeal cancer in the prospective Netherlands cohort study

Our plain-English summary of Occupational asbestos exposure and risk of pleural mesothelioma, lung cancer, and laryngeal cancer in the prospective Netherlands cohort study, by N.S. Offermans, R. Vermeulen, A. Burdorf, et al (Journal of Occupational and Environmental Medicine, 2014).

The study

• Authors: N.S. Offermans, R. Vermeulen, A. Burdorf, R.A. Goldbohm, T. Kauppinen, H. Kromhout, P.A. van den Brandt
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2014;56(1):6-19
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To study the association between occupational asbestos exposure and pleural mesothelioma, lung cancer, and laryngeal cancer, specifically addressing risk associated with the lower end of the exposure distribution, risk of cancer subtypes, and the interaction between asbestos and smoking.

Methods: Using the Netherlands Cohort Study (n = 58,279 men, aged 55 to 69 years), asbestos exposure was estimated by linkage to job-exposure matrices. After 17.3 years of follow-up, 132 pleural mesothelioma, 2324 lung cancer, and 166 laryngeal cancer cases were available.

Results: The multivariable-adjusted model showed overall positive associations between all levels of asbestos exposure and mesothelioma, lung cancer, and laryngeal cancer. Lung adenocarcinoma and glottis cancer showed only a positive association after prolonged higher asbestos exposure (hazard ratio per 10 years increment, 1.43 [95% confidence interval, 1.06 to 1.93] and 1.95 [95% confidence interval, 1.36 to 2.80], respectively). There was no statistically significant interaction between asbestos and smoking.

Conclusions: Asbestos levels encountered at the lower end of the exposure distribution may be associated with an increased risk of pleural mesothelioma, lung cancer, and laryngeal cancer.

In plain English

The authors followed men in the Netherlands Cohort Study, which enrolled 58,279 men aged 55 to 69 in 1986. Occupational asbestos exposure was estimated by linking job histories to a Dutch and a Finnish job-exposure matrix (DOMJEM and FINJEM). After 17.3 years, analyses included 132 pleural mesothelioma, 2324 lung cancer and 166 laryngeal cancer cases. With FINJEM and adjustment for smoking and other factors, hazard ratios for ever-exposed versus never-exposed men were 3.02 (95% CI 2.11 to 4.34) for mesothelioma, 1.50 (1.27 to 1.78) for lung cancer and 1.42 for laryngeal cancer. The laryngeal cancer confidence interval (0.99 to 2.03) included 1, so that result was not statistically significant. Mesothelioma risk was raised even in the lowest FINJEM cumulative exposure group (median 0.20 fiber-years/mL), but not in the lowest DOMJEM group. Lung adenocarcinoma and glottis cancer showed associations only after prolonged high exposure. No statistically significant asbestos-smoking interaction was found. The authors concluded that elevated risks appeared at the lower end of the exposure distribution. They noted possible exposure misclassification from the matrices and low numbers in some subgroups.

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: Prospective population-based cohort study analysed with a case-cohort approach (cases from the whole cohort, person-years from a random subcohort)
• Who was studied: Men from the Netherlands Cohort Study. The cohort began in September 1986 with 58,279 men and 62,573 women aged 55 to 69 from 204 Dutch municipalities, and only men were studied. Follow-up ran 17.3 years, to December 2003. The adjusted analyses included 132 pleural mesothelioma cases, 2324 lung cancer cases and 166 laryngeal cancer cases, compared with 1962 subcohort members (1931 for laryngeal cancer).
• Exposure: Occupational asbestos exposure, with fiber types not distinguished. It was estimated from self-reported lifetime job histories using two job-exposure matrices, the Dutch DOMJEM and the Finnish FINJEM. The exposure measures were: ever versus never exposed; years of exposure; cumulative exposure (fiber-years/mL for FINJEM, unit-years for DOMJEM); and years of high exposure.
• Main results:
  • Ever versus never exposed, multivariable-adjusted. FINJEM: mesothelioma HR 3.02 (95% CI 2.11 to 4.34); lung cancer HR 1.50 (1.27 to 1.78); laryngeal cancer HR 1.42 (0.99 to 2.03). DOMJEM: mesothelioma HR 2.62 (1.82 to 3.76); lung cancer HR 1.19 (1.02 to 1.40); laryngeal cancer HR 1.20 (0.84 to 1.72). The laryngeal cancer intervals include 1.
  • Mesothelioma risk was significantly raised even in the lowest third of cumulative exposure under FINJEM (median 0.20 fiber-years/mL): HR 2.69 (95% CI 1.60 to 4.53). With DOMJEM, no increased risk was seen in the lowest third.
  • Longest duration of high exposure (highest third) versus never highly exposed, using DOMJEM: mesothelioma HR 13.66 (95% CI 5.86 to 31.84); lung cancer HR 2.99 (1.39 to 6.41); laryngeal cancer HR 6.36 (2.18 to 18.53).
  • For lung adenocarcinoma, associations were weaker or absent. The exception was duration of high exposure under DOMJEM: HR 1.43 (95% CI 1.06 to 1.93) per 10 years.
  • Associations were usually stronger for supraglottis cancer than for glottis cancer. The exception was duration of high exposure under DOMJEM: glottis cancer HR 7.09 (95% CI 2.31 to 21.74) for the highest third.
  • No statistically significant additive or multiplicative interaction between asbestos and smoking was found for any of the three cancers.
  • Population-attributable fractions (the estimated share of cases linked to asbestos exposure in this population) were 15.9% to 34.5% for mesothelioma, depending on the exposure measure and matrix used.
  • Population-attributable fractions were 2.5% to 12.1% for lung cancer and 2.9% to 10.0% for laryngeal cancer.
• The authors' conclusion: The authors concluded that the study confirmed associations between asbestos exposure and mesothelioma, lung cancer and laryngeal cancer. They found elevated risks at the lower end of the exposure distribution, also after adjusting for lifestyle confounders such as smoking and alcohol.
• Limitations the authors state:
  • Exposure was based on brief job histories and job-exposure matrices. Exposure misclassification of this kind may have biased the exposure-response relationships.
  • The numbers were low for the subtype analyses, especially supraglottis cancer.
  • The laryngeal cancer interaction results need careful interpretation. Numbers were low, especially among never-smokers not exposed to asbestos.
  • Population-attributable fractions differed between the two matrices, by up to threefold, so matrix-based fractions should be judged with caution.
  • The Finnish matrix was not adapted to Dutch working conditions before it was used.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Throat and laryngeal cancer.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Pleural Mesothelioma, Lung Cancer, Laryngeal Cancer, Cohort Study, Mesothelioma, Lung Adenocarcinoma, Hazard Ratio.

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