Mesothelioma not associated with asbestos exposure

Our plain-English summary of Mesothelioma not associated with asbestos exposure, by B. Jasani, A. Gibbs (Archives of Pathology & Laboratory Medicine, 2012).

The study

• Authors: B. Jasani, A. Gibbs
• Journal: Archives of Pathology & Laboratory Medicine
• Published: 2012;136(3):262-7
• Type of article: Review
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Context: Despite asbestos being identified as the single most important cause of malignant mesothelioma, the tumor is known to occur in only 10% to 20% of heavily exposed individuals. In addition, about 20% of the patients have no history of asbestos exposure even after detailed assessment. Therefore, there has been speculation for some time that asbestos alone may not be sufficient to cause mesothelioma and that other factors may be involved either as cocarcinogens or as independent mechanisms of cancer causation.

Objective: To give a brief review of nonasbestos fiber erionite and therapeutic radiation as 2 established examples of asbestos-independent mechanisms, of the potential emerging role of man-made fibers such as carbon nanotubes, and of polyoma virus SV40 (simian virus 40) as a potential example of the cocarcinogenic mode of involvement.

Data Sources: Relevant recent literature has been surveyed to portray and provide the evidence in favor of the examples.

Conclusions: Erionite has emerged as the most important example of nonasbestos-mediated cause of mesothelioma in regions such as Turkey where exposure to this type of fiber is highly prevalent. Recently, the polyoma virus SV40 has been unexpectedly discovered as an effective cocarcinogen of asbestos in the causation of animal mesothelioma, though despite considerable research, its potential role in human mesothelioma remains unproven.

In plain English

This article was a review, not a new study. The authors surveyed recent published literature on malignant mesothelioma (MM) not associated with asbestos. They described erionite, a fibrous zeolite mineral, and radiation as established non-asbestos examples. They described carbon nanotubes as a possible emerging concern and the monkey virus SV40 as a possible cocarcinogen with asbestos. They reported that several studies of villages in Cappadocia, Turkey, found MM rates about 1000-fold the normal rate, and judged it reasonable to conclude that erionite fibers are carcinogenic. They cited studies linking the X-ray contrast medium Thorotrast to pleural and peritoneal MM in five countries. They also cited a study of 2567 five-year survivors of Hodgkin lymphoma in which irradiated patients had almost 30-fold the general population's MM risk. For carbon nanotubes they noted animal findings but no information on human exposure. In mice and hamsters, low doses of SV40 or asbestos alone did not cause MM, but co-exposure caused significantly more MM. The authors concluded that SV40's role in human mesothelioma remains unproven.

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
• Who was studied: No study population of its own; the review drew on published human, animal and laboratory studies of mesothelioma not linked to asbestos
• Exposure: Non-asbestos agents proposed as causes or cocarcinogens of mesothelioma: erionite, fluoro-edenite, organic (plant silica) fibers, carbon nanotubes, therapeutic radiation and Thorotrast (thorium dioxide), the viruses SV40 and MC29, metals, and chronic serosal inflammation
• Main results:
  • The review reported that several epidemiologic studies of Cappadocian villages in Turkey found MM rates about 1000-fold the normal rate
  • From clinical, epidemiologic, pathologic and experimental studies, the authors judged it reasonable to conclude that erionite fibers are carcinogenic
  • The review cited cohort studies from Denmark, Sweden, Japan, Germany and the United States in which Thorotrast exposure increased the risk of pleural and peritoneal MM
  • The review cited a study by De Bruin et al. of 2567 five-year survivors of Hodgkin lymphoma: patients treated with irradiation had almost 30-fold the MM risk of the general population
  • For carbon nanotubes, the review described animal findings but stated there was no information on human exposures
  • In the mouse and hamster experiments reviewed, the low asbestos doses tested (for example 0.4 mg) did not cause MM on their own
  • In the same animal experiments, co-exposure to SV40 and asbestos caused a significantly higher incidence of MM with a significantly shorter latency
  • The review reported that early molecular studies detected SV40 DNA in 40%–70% of malignant pleural mesothelioma tissue samples
  • The review reported that later studies challenged these findings, suggesting the SV40 DNA detection was most probably an artifact of the PCR method
  • For nickel, silica and beryllium, the authors stated the weight of evidence does not support them as causes of MM in humans
• The authors' conclusion: The authors concluded that SV40 has been found to be an effective cocarcinogen with asbestos in animal mesothelioma, but that its potential role in human mesothelioma remains unproven
• Limitations the authors state:
  • The authors stated that reliable epidemiologic data on SV40 and human mesothelioma are lacking, because SV40-affected and unaffected groups have been hard to tell apart
  • The authors noted that early reports of SV40 antibodies in human blood may partly reflect cross-reactivity with the related human BK and JC viruses

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, Malignant Mesothelioma, Causation, erionite, SV40.

Related studies

• The pathogenesis of mesothelioma — M. Carbone, R.A. Kratzke, et al. (2002)
• Re: "Mesothelioma trends in the United States: an update based on surveillance, epidemiology, and end results program data for 1973 through 2003" — J.H. Lange (2004)
• SV40 enhances the risk of malignant mesothelioma among people exposed to asbestos: a molecular epidemiologic case-control study — A. Cristaudo, R. Foddis, et al. (2005)
• Pathogenesis of malignant pleural mesothelioma — M.C. Jaurand, J. Fleury-Feith (2005)
• Animal models of malignant mesothelioma — A.B. Kane (2006)
• SV40 multiple tissue infection and asbestos exposure in a hyperendemic area for malignant mesothelioma — M. Comar, C. Rizzardi, et al. (2007)

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