Characterization of a French series of female cases of mesothelioma

Our plain-English summary of Characterization of a French series of female cases of mesothelioma, by E. Camiade, C. Gramond, M.A. Jutand, et al (American Journal of Industrial Medicine, 2013).

The study

• Authors: E. Camiade, C. Gramond, M.A. Jutand, S. Audignon, M. Rinaldo, E. Imbernon, D. Luce, F. Galateau-Sallé, P. Astoul, J.C. Pairon, P. Brochard, A. Lacourt
• Journal: American Journal of Industrial Medicine
• Published: 2013;56(11):1307-16
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: More than 80% of mesothelioma cases in men are attributable to occupational asbestos exposure compared to only 40% in women. The objective of the study was to characterize a series of female pleural mesotheliomas according to known and suspected risk factors.

Methods: From the exhaustive recording of 318 female mesothelioma cases in the French National Mesothelioma Surveillance Program between 1998 and 2009, multiple correspondence analysis and hybrid clustering were performed to characterize these cases according to expert assessed occupational and non-occupational exposure to asbestos and man-made vitreous fibers, X-ray exposure, and history of cancer and non-malignant respiratory diseases.

Results: Four clusters were identified: (1) occupational exposure to asbestos and man-made vitreous fibers (7.9% of subjects); (2) radiation exposure during radiotherapy (12.9%); (3) increased asbestos exposure (19.8%); and (4) "non-exposure" characteristics (59.4%).

Conclusion: These results will allow hypotheses to be generated about associations between mesothelioma and non-occupational asbestos exposure, X-ray exposure and history of respiratory disease.

Copyright © 2013 Wiley Periodicals, Inc.

In plain English

This French study described 318 women with malignant pleural mesothelioma in the National Mesothelioma Surveillance Program between 1998 and 2009. Two industrial hygienists assessed each woman's asbestos and man-made vitreous fiber exposure from questionnaires and interviews. The exception was environmental exposure, defined as having lived in a town with an asbestos-processing plant. The authors recorded X-ray exposure, cancer history and non-malignant respiratory disease, then clustered the women. Overall, 43.4% had occupational asbestos exposure. Four clusters emerged. The first (7.9%) was marked by occupational exposure to man-made vitreous fibers and asbestos. The second (12.9%) was marked by radiotherapy and cancer history. The third (19.8%) combined higher occupational, para-occupational and environmental asbestos exposure. The fourth (59.4%) was marked mainly by no identified exposure. Among the 180 never occupationally exposed women, a cluster marked by long-term para-occupational and environmental exposure included 28.9%. The authors concluded this points to a possible role of non-occupational asbestos exposure in these women. They stated that their methods only raise hypotheses and cannot assess causes or associations with the disease. They named identifying environmental exposure as the main limitation of their exposure assessment.

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: Exploratory, descriptive analysis of a case series (multiple correspondence analysis and hybrid clustering); there was no comparison group without mesothelioma
• Who was studied: Women with confirmed malignant pleural mesothelioma who were alive and registered in the French National Mesothelioma Surveillance Program (PNSM) from January 1, 1998 to December 31, 2009. Of 343 who were registered and interviewed, 318 had complete information and were analyzed. In a separate analysis they were split into 180 never occupationally exposed to asbestos (subset 1) and 138 occupationally exposed (subset 2).
• Exposure: Lifetime exposure to asbestos and to man-made vitreous fibers (no specific asbestos fiber types are named). Exposure sources covered were occupational, do-it-yourself home repair, para-occupational (living with an asbestos worker, cleaning contaminated clothes), domestic, and environmental. Two industrial hygienists assessed exposure, with occupational exposure expressed as a cumulative exposure index in f/ml-years. Environmental exposure was not assessed by the experts: a woman counted as exposed if she had lived in at least one town with an asbestos-processing plant, whatever the town size or distance from the plant. The study also covered X-ray exposure (radiotherapy or repeated diagnostic X-rays), history of familial or personal cancer, and non-malignant respiratory disease.
• Main results:
  • Of the 318 women, 43.4% had a history of occupational asbestos exposure; about 20.0% had para-occupational or domestic exposure.
  • Potential environmental asbestos exposure was found in 51.9% of the 318 women.
  • Cluster 1 (25 women, 7.9% of 318) was marked by occupational exposure to man-made vitreous fibers (100% within the cluster vs 7.9% overall) and occupational asbestos exposure with a cumulative index of 0.006 to under 0.225 f/ml-years (60.0% vs 22.0% overall).
  • Cluster 2 (41 women, 12.9% of 318) was marked by a history of radiotherapy (80.5% within the cluster vs 11.6% overall) and of family or personal cancer (90.2% vs 60.1%).
  • Cluster 3 (63 women, 19.8% of 318) was marked by occupational asbestos exposure in the highest index category of 0.225 f/ml-years or more (41.3% vs 10.4% overall), together with long-term para-occupational exposure (65.1% vs 13.8%) and long-term environmental exposure (41.3% vs 24.5%).
  • Cluster 4, the largest (189 women, 59.4% of 318), was characterized mainly by non-exposure categories.
  • Neither age at diagnosis nor histological type characterized any cluster.
  • Among the 180 women never occupationally exposed to asbestos, a cluster marked only by long-term para-occupational and environmental exposure made up 28.9%. Among the 138 occupationally exposed women, a similar cluster made up 43.5%.
  • Among the 180 women never occupationally exposed, the largest cluster (47.2%) was characterized mainly by non-exposure categories.
  • A history of non-malignant respiratory disease always went together with a history of repeated X-rays, so the authors could not separate the two.
• The authors' conclusion: The authors concluded that this exploratory analysis points to a possible role of non-occupational asbestos exposure (para-occupational and environmental) in pleural mesothelioma in women never occupationally exposed. They also concluded that environmental asbestos exposure should be adjusted for when studying occupational and para-occupational exposure, and that a gender-specific case-control study is needed to test these hypotheses.
• Limitations the authors state:
  • The statistical methods can only generate hypotheses. They cannot assess the causal role of any factor or any association between these factors and the disease.
  • The authors named the identification of environmental exposure as the main limitation of the asbestos exposure assessment. It relied on a list of asbestos establishments, and sources such as the construction industry were not systematically identified.
  • The large 'non-exposure' cluster may mean that some asbestos exposure was missed, or that these women were characterized by other factors not studied.
  • Self-reported questionnaire data depend on memory, so recall bias could have led to over- or underestimation of asbestos exposure.
  • A history of non-malignant respiratory disease may have been underestimated because such events often occurred many years before diagnosis.
  • Radiotherapy exposure was recorded only as ever or never, regardless of irradiation field, so its assessment was of low reliability.
  • The method is sensitive to small categories, so very small clusters (under 6% of the sample in the subset analyses) should be interpreted with caution.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos Exposure, Pleural Mesothelioma, Non-Occupational Exposure, Vitreous, Occupational Exposure.

Related studies

• Solid cancer mortality associated with chronic external radiation exposure at the French atomic energy commission and nuclear fuel company — C. Metz-Flamant, E. Samson, et al. (2011)
• Attributable risk in men in two French case-control studies on mesothelioma and asbestos — A. Lacourt, P. Rolland, et al. (2010)
• Impact of chemical exposure on cancer mortality in a French cohort of uranium processing workers — S. Zhivin, D. Laurier, et al. (2013)
• Compensation of pleural mesothelioma in France: data from the French National Mesothelioma Surveillance Programme — S. Chamming's, B. Clin, et al. (2013)
• Occupational and non-occupational attributable risk of asbestos exposure for malignant pleural mesothelioma — A. Lacourt, C. Gramond, et al. (2014)
• Occupations and industries in France at high risk for pleural mesothelioma: A population-based case-control study (1998-2002) — P. Rolland, C. Gramond, et al. (2010)

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