Five years update on relationships between malignant pleural mesothelioma and exposure to asbestos and other elongated mineral particles

Our plain-English summary of Five years update on relationships between malignant pleural mesothelioma and exposure to asbestos and other elongated mineral particles, by P. Andujar, A. Lacourt, P. Brochard, et al (Journal of Toxicology and Environmental Health. Part B, Critical Reviews, 2016).

The study

• Authors: P. Andujar, A. Lacourt, P. Brochard, J.C. Pairon, M.C. Jaurand, D. Jean
• Journal: Journal of Toxicology and Environmental Health. Part B, Critical Reviews
• Published: 2016;19(5-6):151-172
• Type of article: Review
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Despite the reduction of global asbestos consumption and production due to the ban or restriction of asbestos uses in more than 50 countries since the 1970s, malignant mesothelioma remains a disease of concern. Asbestos is still used, imported, and exported in several countries, and the number of mesothelioma deaths may be expected to increase in the next decades in these countries. Asbestos exposure is the main risk factor for malignant pleural mesothelioma, but other types of exposures are linked to the occurrence of this type of cancer. Although recent treatments improve the quality of life of patients with mesothelioma, malignant pleural mesothelioma remains an aggressive disease. Recent treatments have not resulted in appreciable improvement in survival, and thus development of more efficient therapies is urgently needed. The development of novel therapeutic strategies is dependent on our level of knowledge of the physiopathological and molecular changes that mesothelial cells acquired during the neoplastic process. During the past 5 years, new findings have been published on the etiology, epidemiology, molecular changes, and innovative treatments of malignant pleural mesothelioma. This review aims to update the findings of recent investigations on etiology, epidemiology, and molecular changes with a focus on (1) attributable risk of asbestos exposure in men and women and (2) coexposure to other minerals and other elongated mineral particles or high aspect ratio nanoparticles. Recent data obtained on genomic and gene alterations, pathways deregulations, and predisposing factors are summarized.

In plain English

This review covered research on malignant pleural mesothelioma published in about the previous five years. It focused on asbestos-attributable risk in men and women, on combined exposure to asbestos and other particles, and on tumor genetics. The authors summarized existing reviews rather than reviewing all the epidemiological literature. Cited French and UK studies attributed 86.4% to 87.3% of male cases and 38.1% to 64.8% of female cases to any asbestos source. In a cited French case-control study of male cases, the odds ratio for occupational asbestos exposure alone at 1 to 10 fibers/ml-yr was 3.7, compared with subjects unexposed to asbestos, mineral wool and silica. Against the same group, it was 7.1 with added mineral wool, 8.9 with added silica, and 10.3 with asbestos, mineral wool and silica combined. The authors noted that German and Canadian coexposure results had wide, overlapping confidence intervals and might reflect confounding by asbestos. They reported that inherited BAP1 mutations are infrequent in non-familial mesothelioma. The authors concluded that man-made vitreous fibers now appear to be potential cofactors that increase mesothelioma risk.

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: Review: a summary of literature published over about the previous 5 years, with findings drawn from other studies
• Who was studied: Published studies (roughly the previous 5 years) on malignant pleural mesothelioma epidemiology, coexposures, tumor genetics and predisposing factors
• Exposure: Asbestos, including chrysotile and amphiboles (crocidolite, amosite, anthophyllite, tremolite, actinolite). Also other elongated mineral particles (Libby amphiboles winchite and richterite, fluoro-edenite, erionite), synthetic vitreous fibers including mineral wool and refractory ceramic fibers, silica, and high aspect ratio nanoparticles such as carbon nanotubes
• Main results:
  • From cited French and UK studies: the attributable risk of occupational asbestos exposure for pleural mesothelioma in men ranged from 83.1% in France to 85% in the United Kingdom
  • From cited studies: in women, the attributable risk of occupational asbestos exposure was lower, from 22.5% in the United States to 41.7% in France
  • From cited French and UK studies: 86.4% to 87.3% of male cases and 38.1% to 64.8% of female cases were attributed to any source of asbestos exposure
  • The authors noted that, in women, an unexplained part of the attributable risk (approximately one-third) remains
  • A cited study of 318 female mesothelioma cases in the French National Mesothelioma Surveillance Program (1998 to 2009) identified 4 clusters: occupational asbestos and man-made vitreous fibers (7.9%), radiotherapy radiation (12.9%), any asbestos exposure (19.8%), and 'nonexposure' characteristics (59.4%)
  • The three cited population-based coexposure case-control studies (Germany, Canada, France) included only incident, histologically confirmed male cases
  • Cited French case-control study (1,199 cases, 2,379 controls): for subjects occupationally exposed only to asbestos at 1 to 10 fibers/ml-yr, the odds ratio was 3.7 compared with subjects not exposed to asbestos, mineral wool and silica
  • In the same French study and against the same comparison group, the odds ratio rose to 7.1 for subjects additionally exposed to mineral wool, 8.9 for those additionally exposed to silica, and 10.3 for those exposed to all three particles (asbestos, mineral wool and silica)
  • Same French study, restricted to subjects ever exposed to asbestos (988 cases, 1,125 controls): the odds ratio was 1.9 for asbestos alone at 50 fibers/ml-yr and 12.8 with added refractory ceramic fibers
  • Cited German case-control study (125 cases, 125 controls, Hamburg, 1988 to 1991): odds ratios were 19.8 for asbestos only, 15.1 for man-made vitreous fibers only, and 61.3 for both
  • Cited French ARDCO cohort of asbestos-exposed men (n = 5,287): pleural plaques seen on CT scan were associated with pleural mesothelioma. The hazard ratio was 8.9 unadjusted and 6.8 after adjustment for time since first exposure and cumulative asbestos exposure
  • For refractory ceramic fibers, earlier human studies established no significant link with pleural mesothelioma, and the authors knew of no new epidemiological data
  • Inherited (germline) BAP1 mutations were reported as infrequent in sporadic mesothelioma, and no asbestos-specific genetic signature in mesothelioma has been identified
• The authors' conclusion: The authors concluded that the link between asbestos and pleural mesothelioma is well established. They found the attributable risk higher in men for occupational exposure and higher in women for nonoccupational exposure. They concluded that man-made vitreous fibers now appear to be potential cofactors that increase the risk of pleural mesothelioma, and wrote that coexposures to asbestos and some man-made fibers or silica enhance mesothelioma risk and should be further investigated
• Limitations the authors state:
  • The authors did not undertake a comprehensive review of the epidemiological literature but summarized findings from other recent reviews
  • In the German and Canadian coexposure studies, the 95% confidence intervals were wide and overlapped
  • The higher odds ratios for combined asbestos and man-made vitreous fiber exposure in those studies may reflect confounding by asbestos exposure
  • Cohort studies of workers have not examined the combined effect of asbestos and other particles

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: Pleural Mesothelioma, Malignant Mesothelioma, Mesothelioma, Asbestos Exposure, Quality of Life, Mesothelial Cells, Etiology, Epidemiology.

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