The diagnostic role of BAP1 in serous effusions

Our plain-English summary of The diagnostic role of BAP1 in serous effusions, by B. Davidson, M. Tötsch, J. Wohlschlaeger, et al (Human Pathology, 2018).

The study

• Authors: B. Davidson, M. Tötsch, J. Wohlschlaeger, T. Hager, M. Pinamonti
• Journal: Human Pathology
• Published: 2018;79:122-126
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The aim of this study was to analyze the diagnostic role of BAP1 in effusion cytology. Effusions (n = 258), consisting of 53 malignant mesotheliomas and 205 other cancers, the majority carcinomas (62 breast, 60 ovarian, 31 lung, 51 carcinomas of other origin, 1 melanoma), were analyzed for BAP1 expression using immunohistochemistry. BAP1 was lost in 46 (87%) mesotheliomas compared with 4 (2%) of 205 other cancers (P < .001), resulting in sensitivity and specificity of 87% and 98%, respectively. There was no significant difference between peritoneal (n = 14) and pleural (n = 39) mesotheliomas. The 4 carcinomas with loss of BAP1 included 1 ovarian, 1 breast, 1 uterine cervical, and 1 gastric carcinoma. The present study supports the role of BAP1 as a highly sensitive and specific marker for malignant mesothelioma in serous effusions and argues for inclusion of this test in all specimens in which this diagnosis is considered.

Copyright © 2018 Elsevier Inc. All rights reserved.

In plain English

This laboratory study tested whether staining for a protein called BAP1 helps tell malignant mesothelioma apart from other cancers in fluid collecting in the chest or abdominal cavities (serous effusions). The authors examined 258 effusion specimens: 53 malignant mesotheliomas (39 pleural, 14 peritoneal, all epithelioid or biphasic type) and 205 other cancers, mostly breast, ovarian and lung carcinomas. Most specimens came from the Norwegian Radium Hospital between 1998 and 2008. The article does not report asbestos exposure. BAP1 was lost in 46 of 53 mesotheliomas (87%), including 11 of 14 peritoneal and 35 of 39 pleural tumors. The difference between pleural and peritoneal tumors was not statistically significant. BAP1 was lost in 4 of 205 other cancers (2%): one ovarian, one breast, one cervical and one gastric carcinoma. The test's sensitivity was 87% and its specificity 98%. The authors concluded that BAP1 should be included in the tests used to distinguish mesothelioma from carcinoma in effusions. They noted that the four carcinomas with BAP1 loss need to be taken into account.

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 diagnostic study: immunohistochemical staining for BAP1 on cell blocks from malignant effusions, comparing malignant mesothelioma with other cancers (collaborative study across several European centers)
• Who was studied: 258 malignant effusion specimens. 201 came from the Norwegian Radium Hospital, Oslo, from 1998 to 2008; the rest came from Trieste, Italy (31), Graz, Austria (13), Ålborg, Denmark (8) and Essen, Germany (5). They comprised 53 malignant mesotheliomas (39 pleural, 14 peritoneal; all epithelioid or biphasic type) and 205 other cancers (62 breast, 60 ovarian, 31 lung, other carcinomas and 1 melanoma).
• Exposure: No asbestos exposure was studied or reported. The factor examined was BAP1 protein staining in tumor cell nuclei, scored as absent or retained.
• Main results:
  • Among the 53 malignant mesotheliomas, BAP1 was lost in 46 (87%). This included 11 of 14 peritoneal and 35 of 39 pleural tumors.
  • The difference in BAP1 loss between peritoneal and pleural mesothelioma was not statistically significant (P = .294).
  • BAP1 was lost in 4 (2%) of the 205 non-mesothelioma cancers, 204 of which were carcinomas.
  • The 4 carcinomas with BAP1 loss were 1 ovarian high-grade serous carcinoma, 1 breast carcinoma (no special type), 1 uterine cervical squamous cell carcinoma and 1 gastric adenocarcinoma.
  • The difference in BAP1 expression between mesothelioma and non-mesothelioma cancers was statistically significant (p less than 0.001). For diagnosing mesothelioma, the test had a sensitivity of 87% and a specificity of 98%.
  • BAP1 staining was consistently present in reactive (non-cancerous) mesothelial cells in the carcinoma specimens and in white blood cells in all specimens.
• The authors' conclusion: The authors concluded that loss of BAP1 is highly sensitive and specific for diagnosing malignant mesothelioma in effusions. They concluded that BAP1 should be included in the diagnostic panel used to distinguish mesothelioma from carcinoma in serous effusion cytology.
• Limitations the authors state:
  • The authors noted that the 4 carcinomas showing BAP1 loss need to be taken into account.
  • The authors stated that it is unclear why their sensitivity (87%) was higher than in earlier studies (from 53%), and that technical aspects may play a role.
  • The authors stated that the study did not set out to examine BAP1 for distinguishing mesothelioma from reactive (benign) mesothelial cells.

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: BAP1, Cytology, Malignant Mesothelioma, Carcinoma, Immunohistochemistry, Mesothelioma.

Related studies

• MMP-7 is a highly specific negative marker for benign and malignant mesothelial cells in serous effusions — B. Davidson, H.T. Stavnes, et al. (2016)
• Utility of BAP1 Immunohistochemistry and p16 (CDKN2A) FISH in the Diagnosis of Malignant Mesothelioma in Effusion Cytology Specimens — H.C. Hwang, B.S. Sheffield, et al. (2016)
• BAP1 Immunostain and CDKN2A (p16) FISH Analysis: Clinical Applicability for the Diagnosis of Malignant Mesothelioma in Effusions — A.E. Walts, K. Hiroshima, et al. (2016)
• The value of BRCA-1-associated protein 1 expression and cyclin-dependent kinase inhibitor 2A deletion to distinguish peritoneal malignant mesothelioma from peritoneal location of carcinoma in effusion cytology specimens — W. Althakfi, S. Gazzo, et al. (2020)
• PAX8 Expression in a Subset of Malignant Peritoneal Mesotheliomas and Benign Mesothelium has Diagnostic Implications in the Differential Diagnosis of Ovarian Serous Carcinoma — D.B. Chapel, A.N. Husain, et al. (2017)
• Loss of BRCA1-associated protein 1 (BAP1) expression is useful in diagnostic cytopathology of malignant mesothelioma in effusions — I. Cozzi, F.A. Oprescu, et al. (2018)

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