Comparison of genomic abnormality in malignant mesothelioma by the site of origin

Our plain-English summary of Comparison of genomic abnormality in malignant mesothelioma by the site of origin, by M. Takeda, T. Kasai, Y. Enomoto, et al (Journal of Clinical Pathology, 2014).

The study

• Authors: M. Takeda, T. Kasai, Y. Enomoto, M. Takano, K. Morita, T. Nakai, N. Iizuka, H. Maruyama, C. Ohbayashi
• Journal: Journal of Clinical Pathology
• Published: 2014;67(12):1038-43
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims: Malignant mesothelioma (MM) results from the accumulation of a number of acquired genetic events at the onset. In MM, the most frequent changes are losses in 9p21, 1p36, 22q12 and 14q32, and gains in 5p, 7p and 8q24 by comparative genomic hybridisation analysis. We have examined various genomic losses and gains in MM and benign mesothelial proliferation by fluorescence in situ hybridisation (FISH) analysis. 9p21 deletion was reported to be less frequent in peritoneal than in pleural MMs. This study analysed various genomic losses and gains in MM by the site of origin using FISH analysis.

Materials And Methods: We performed FISH analysis using paraffin-embedded tissues from 54 cases (40 pleural and 14 peritoneal) of MMs and compared the frequency of genomic abnormality by the site of origin.

Results: 9p21 deletion was shown in 34 of 40 cases (85%) of pleural MMs, and was less frequent in five of 14 cases (36%) of peritoneal MMs (p<0.001) by FISH analysis. By contrast, 5p15 and 7p12 amplification was more significantly frequent in peritoneal than in pleural MMs. No difference between the two sites of MM in other genes was found.

Conclusions: 9p21 homozygous deletion assessed by FISH has been reported to be useful for differentiating MM from reactive mesothelial proliferation, but it should be noted that 9p21 deletion was less frequent in peritoneal MM. Our study suggests that the pathway of the genetic abnormality might vary between pleural and peritoneal MM.

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In plain English

This laboratory study from Japan compared genetic changes in tumour tissue from 54 people with malignant mesothelioma: 40 pleural (lining of the chest) and 14 peritoneal (lining of the abdomen). The authors used archived tissue and fluorescence in situ hybridisation (FISH), a technique that detects lost or extra copies of chromosome regions, to examine eight regions. Loss of both copies of the 9p21 region was found in 34 of 40 pleural cases (85%) but in 5 of 14 peritoneal cases (36%). Extra copies of 5p15.2 were found in 19 of 40 pleural cases (48%) and 13 of 14 peritoneal cases (93%). Extra copies of 7p12 were found in 12 of 40 pleural cases (30%) and 9 of 14 peritoneal cases (64%). These differences were statistically significant. The other regions showed no significant difference by site. The authors found no significant differences by gender, age or tumour subtype. As far as they could examine, they found no statistical correlation between asbestos exposure and the genetic changes; the article does not describe the exposures. The authors concluded that the pathway of genetic change might differ between pleural and peritoneal mesothelioma, and they called for larger studies.

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: Laboratory comparison of archived tumour tissue (FISH analysis of paraffin-embedded samples), pleural versus peritoneal malignant mesothelioma
• Who was studied: 54 cases of malignant mesothelioma (40 pleural, 14 peritoneal) from the archives of Nara Medical University, Kishiwada City Hospital and Hoshigaoka Koseinenkin Hospital, Japan. Subtypes were 34 epithelioid, 10 biphasic and 10 sarcomatoid. Some cases had been reported in the authors' earlier studies. Collection dates are not given.
• Exposure: The study examined genetic changes in tumours: deletions of 9p21, 22q12, 1p36 and 14q32, and amplifications of 5p15.2, 7p12, 8q24 and the chromosome 6 centromere. Asbestos exposure is mentioned only in one analysis. No fiber types, jobs or doses are described.
• Main results:
  • Homozygous 9p21 deletion was found in 34 of 40 pleural cases (85%) and 5 of 14 peritoneal cases (36%); p<0.001.
  • 5p15.2 amplification was found in 19 of 40 pleural cases (48%) and 13 of 14 peritoneal cases (93%); p<0.01.
  • 7p12 amplification was found in 12 of 40 pleural cases (30%) and 9 of 14 peritoneal cases (64%); p<0.05.
  • There was no significant difference by site for deletion of 1p36, 22q12 and 14q32, or for amplification of 8q24 and 6p11.1-q11.
  • There was no significant difference in the frequency of genetic changes by gender, age or histological subtype.
  • As far as the authors could examine, there was no statistical correlation between asbestos exposure and the genetic changes.
• The authors' conclusion: The authors concluded that the pathway of genetic abnormality might be different between pleural and peritoneal mesothelioma. They also noted that 9p21 deletion, which has been reported to be useful in diagnosis, was less frequent in peritoneal mesothelioma.
• Limitations the authors state:
  • The authors stated that further studies on a larger series of patients, covering asbestos exposure and genetic changes by site, are needed.

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Fluorescence In Situ Hybridization (FISH), Homozygous Deletion.

Related studies

• A comparison of epidermal growth factor receptor expression in malignant peritoneal and pleural mesothelioma — Y. Enomoto, T. Kasai, et al. (2012)
• Association Between Clinicopathological Factors and Genomic Abnormalities Detected by FISH Analysis in Epithelioid Diffuse Malignant Pleural Mesothelioma — M. Takeda, T. Kasai, et al. (2017)
• Genomic gains and losses in malignant mesothelioma demonstrated by FISH analysis of paraffin-embedded tissues — M. Takeda, T. Kasai, et al. (2012)
• Epidermal growth factor receptor mutations in malignant pleural and peritoneal mesothelioma — Y. Enomoto, T. Kasai, et al. (2012)
• 9p21 deletion in the diagnosis of malignant mesothelioma, using fluorescence in situ hybridization analysis — M. Takeda, T. Kasai, et al. (2010)
• Complete cytoreductive surgery plus HIPEC for peritoneal metastases from unusual cancer sites of origin: results from a worldwide analysis issue of the Peritoneal Surface Oncology Group International (PSOGI) — D. Goéré, G. Passot, et al. (2017)

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