Occupational toxicology of asbestos-related malignancies

Our plain-English summary of Occupational toxicology of asbestos-related malignancies, by M. Lotti, L. Bergamo, B. Murer (Clinical Toxicology, 2010).

The study

• Authors: M. Lotti, L. Bergamo, B. Murer
• Journal: Clinical Toxicology
• Published: 2010;48(6):485-96
• Type of article: Review
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Asbestos is banned in most Western countries but related malignancies are still of clinical concern because of their long latencies. This review identifies and addresses some controversial occupational and clinical aspects of asbestos-related malignancies.

Methods: Papers published in English from 1980 to 2009 were retrieved from PubMed. A total of 307 original articles were identified and 159 were included.

Assessment Of Exposure: The retrospective assessment of exposure is usually performed by using questionnaires and job exposure matrices and by careful collection of medical history. In this way crucial information about manufacturing processes and specific jobs can be obtained. In addition, fibers and asbestos bodies are counted in lung tissue, broncho-alveolar lavage, and sputum, but different techniques and interlaboratory variability hamper the interpretation of reported measurements. SCREENING FOR MALIGNANCIES: The effectiveness of low-dose chest CT screening in exposed workers is debatable. Several biomarkers have also been considered to screen individuals at risk for lung cancer and mesothelioma but reliable signatures are still missing. ATTRIBUTION OF LUNG CANCER: Exposures correlating with lung cancer are high and in the same range where asbestosis occurs. However, the unresolved question is whether the presence of fibrosis is a requirement for the attribution of lung cancer to asbestos. The etiology of lung cancer is difficult to define in cases of low-level asbestos exposure and concurrent smoking habits. MESOTHELIOMA: The diagnosis of malignant mesothelioma may also be difficult, because of procedures in sampling, fixation, and processing, and uses of immunohistochemical probes.

Conclusions: Assessment of exposure is crucial and requires accurate medical and occupational histories. Quantitative analysis of asbestos body burden is better performed in digested lung tissues by counting asbestos bodies by light microscopy and/or uncoated fibers by transmission electron microscopy. The benefits of screenings for asbestos-related malignancies are equivocal. The attribution of lung cancer to asbestos exposure is difficult in a clinical setting because of the need to assess asbestos body burden and the fact that virtually all these patients are also tobacco smokers or former smokers. Given the premise that asbestosis is necessary to causally link lung cancer to asbestos, it follows that the assessment of both lung fibrosis and asbestos body burden is necessary.

In plain English

This was a review of other researchers' published work, not a new study. Its authors, based in Padova and Mestre, Italy, searched PubMed for English-language papers published from 1980 to 2009. They included 159 papers, chosen by their own judgment of quality and relevance. The review covered four topics: assessing past asbestos exposure, screening exposed workers, attributing lung cancer to asbestos, and diagnosing malignant mesothelioma. Drawing on other researchers' work, the authors reported that fiber counts vary between laboratories because standardized methods are lacking. They also reported that the effectiveness of low-dose chest CT screening in exposed workers is debatable, and that reliable biomarkers for early detection were still missing. They wrote that it remains unresolved whether asbestosis (lung fibrosis) must be present before lung cancer can be attributed to asbestos. They also wrote that no criteria exist to weigh the relative contributions of asbestos and smoking. Conflicting stain results could complicate mesothelioma diagnosis. The authors concluded that both lung fibrosis and asbestos body burden should be assessed, and that there is no valid substitute for clinical judgment.

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: Narrative review of published literature on diagnostic issues in asbestos-related malignancies
• Who was studied: 159 papers published in English from 1980 to 2009, retrieved from PubMed. Review articles were searched first, then original articles cited in them, with a 2009 update. Final inclusion was based on the authors' judgment of quality and relevance.
• Exposure: Asbestos exposure in general, mainly occupational. The article describes amphiboles (crocidolite, amosite, anthophyllite, tremolite) and the serpentine chrysotile. It considers the outcomes lung cancer and malignant mesothelioma.
• Main results:
  • Based on the literature reviewed, the authors reported that variability between laboratories in counting asbestos fibers in lung tissue is large because standardized analytical methods are not available.
  • The authors described the effectiveness of low-dose chest CT screening in exposed workers as debatable.
  • The authors stated that reliable biomarkers for screening or early detection of asbestos-associated lung tumors were still missing.
  • Citing one study, the authors reported that high mesothelin concentrations in blood and pleural effusion were associated with mesothelioma, with a specificity of 98% and a sensitivity of 67%.
  • The authors noted that the Helsinki Report estimated that a cumulative exposure of 25 fibers/mL-years doubles lung cancer risk. They added that a later reevaluation concluded the exposures linked to increased risk are probably higher.
  • On whether asbestosis must be present for lung cancer to be attributed to asbestos, the authors cited a review of nine epidemiological studies. That review concluded the question is unanswerable epidemiologically.
  • The authors stated that pleural plaques indicate past exposure but do not substitute for estimating a high asbestos body burden.
  • The authors reported that, according to epidemiological evidence, smoking and asbestos exposure together have more than additive but less than multiplicative effects on lung cancer incidence.
  • The authors stated that no criteria have been suggested to assess the relative contribution of asbestos and smoking to lung cancer.
  • For mesothelioma diagnosis, the authors reported that the same antibody stains have given conflicting results in up to 30% of cases. They attributed this to differences in sampling, fixation and processing, among other factors.
  • Citing other studies, the authors reported that ancillary techniques such as cytochemistry and immunocytochemistry raise the sensitivity of cytological diagnosis of malignant mesothelioma to 98%.
  • The authors stated that assessment of both lung fibrosis and asbestos body burden is necessary when attributing lung cancer to asbestos.
• The authors' conclusion: The authors concluded that experts are far from consensus on asbestos-related malignancies, and that there is no valid substitute for clinical judgment in diagnosing and following formerly exposed individuals.
• Limitations the authors state:
  • The authors stated that the review does not offer a viewpoint on medico-legal aspects, which they said are covered elsewhere.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Sputum, Biomarker, Lung Cancer, Mesothelioma, Attribution, Fibrosis, Etiology.

Related studies

• Four-miRNA Signature to Identify Asbestos-Related Lung Malignancies — L. Santarelli, S. Gaetani, et al. (2019)
• Assessment of bibliographic databases performance in information retrieval for occupational and environmental toxicology — J.F. Gehanno, C. Paris, et al. (1998)
• New insights on 'old' toxicants in occupational toxicology (Review) — C. Costa, E. Miozzi, et al. (2017)
• Developments in industrial and occupational toxicology: REACH, toxicogenomics, mycotoxins, lead, asbestos, boron, bitumen, deletions polymorphisms and SNP interactions: meeting report of the 16th EUROTOX training and discussion session — G.H. Degen, J.G. Hengstler (2008)
• Differential reactivities of carcinoembryonic antigen (CEA) and CEA-related monoclonal and polyclonal antibodies in common epithelial malignancies — K. Sheahan, M.J. O'Brien, et al. (1990)
• Lymphoid and plasma cell malignancies: asbestos-related disorders of long latency — E. Kagan, R.J. Jacobson (1983)

Browse return to medical research.