OV632 as a possible marker for malignant mesothelioma: high expectations; low specificity

Our plain-English summary of OV632 as a possible marker for malignant mesothelioma: high expectations; low specificity, by A. Abati, P.A. Fetsch (Diagnostic Cytopathology, 1995).

The study

• Authors: A. Abati, P.A. Fetsch
• Journal: Diagnostic Cytopathology
• Published: 1995;12(1):81-2
• Type of article: Editorial
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter, the authors, at the National Cancer Institute in Bethesda, Maryland, reported a small trial of the monoclonal antibody OV632 as a marker for malignant mesothelioma. Earlier reports had stated that OV632 selectively stained nonmucinous ovarian adenocarcinomas and malignant mesotheliomas, rarely stained other tumours, and did not stain reactive mesothelial cells. Over a 6-week period the authors selected cases offering a range of diagnoses from body fluids and fine-needle aspirates. These included metastatic breast and ovarian adenocarcinomas, mesothelioma, reactive mesothelial cells, melanoma, squamous cell carcinoma and lymphoma. They stained two kinds of preparation with OV632 using the avidin-biotin peroxidase method, with negative controls: air-dried cytospins that had been stored frozen and fixed in acetone, and formaldehyde-fixed paraffin cell blocks. On cytospins, one breast adenocarcinoma was technically unsatisfactory, and four of five metastatic breast adenocarcinomas stained positive. Positive staining was also seen in the mesothelioma, reactive mesothelial cells, malignant melanoma, squamous cell carcinoma and large-cell lymphoma. The single metastatic ovarian adenocarcinoma was negative. Cell block sections could not be interpreted because of uniformly high background staining. The authors had no explanation for results contrary to expectations, since reagents were fresh and the manufacturer's procedure was followed. They did not add OV632 to their routine panel for suspected mesothelioma in male patients. They asked other laboratories to report their experience and said they would use OV632 only on an experimental basis.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This letter to the editor, by two National Cancer Institute authors, described a small laboratory trial of OV632, an antibody that earlier reports had suggested might help identify malignant mesothelioma. Over a 6-week period, the authors selected cytology cases with a range of diagnoses (fluid samples and needle aspirates). Their table lists 12 cases. They stained air-dried cytospin slides and formaldehyde-fixed cell block sections with OV632. On the cytospins, staining was positive in four of five metastatic breast adenocarcinomas; a sixth breast case was technically unsatisfactory. Staining was also positive in the mesothelioma, in reactive (benign) mesothelial cells, and in malignant melanoma, squamous cell carcinoma and large-cell lymphoma. The one metastatic ovarian adenocarcinoma did not stain. The cell block slides could not be interpreted because of high background staining. The authors said they had no explanation for these results, which were contrary to what they expected. They concluded that, based on this small trial, OV632 had not joined their usual stain panel for suspected mesothelioma in male patients, and that they would use it only experimentally. The letter did not study asbestos exposure.

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: Letter to the editor reporting a small laboratory trial of an immunostain (antibody test) on cytology specimens
• Who was studied: Cytology cases with a range of diagnoses selected over a 6-week period, mainly pleural and peritoneal fluids and fine-needle aspirates. The table lists 12 cases: 6 metastatic breast adenocarcinomas, 1 ovarian adenocarcinoma, 1 mesothelioma, 1 squamous cell carcinoma, 1 melanoma, 1 large B-cell lymphoma and 1 case of reactive mesothelial cells. The authors were at the National Cancer Institute, Bethesda, Maryland.
• Exposure: No asbestos exposure was studied. The test was the OV632 monoclonal antibody, applied at a 1:10 dilution (printed as "1:lO" by the scan) to air-dried cytospins and to paraffin-embedded, formaldehyde-fixed cell block material.
• Main results:
  • Among metastatic breast adenocarcinomas, OV632 staining was positive in four of five evaluable cases. One further breast case was technically unsatisfactory.
  • Positive staining was also obtained in the mesothelioma case.
  • Positive staining was also obtained with reactive mesothelial cells, malignant melanoma, squamous cell carcinoma and large-cell lymphoma.
  • The single metastatic ovarian adenocarcinoma did not stain.
  • Assays on the formaldehyde-fixed cell block sections could not be interpreted because of uniformly high background staining.
• The authors' conclusion: The authors concluded that, based on this small trial, OV632 would not become part of their usual stain panel for suspected mesothelioma in male patients. They said they would use it only on an experimental basis until other laboratories' experience clarifies its usefulness.
• Limitations the authors state:
  • The authors described the study as a small trial.
  • The authors stated they had no explanation for their results, which were contrary to what they expected.
  • The authors' slide fixation technique differed slightly from that used in an earlier study (Delahaye et al.).

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Monoclonal Antibody, Adenocarcinoma, Reactive Mesothelial Cells, Aspirate, Mesothelioma, Squamous Cell Carcinoma, Cell Block.

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• Keratins 7 and 20 as diagnostic markers of carcinomas metastatic to the ovary — C.C. Wauters, F. Smedts, et al. (1995)
• CD24 is highly useful in differentiating high-grade serous carcinoma from benign and malignant mesothelial cells — B. Davidson (2016)
• Cytokeratin 5/6 expression, prognosis, and association with estrogen receptor α in high-grade serous ovarian carcinoma — E.T. Taube, C. Denkert, et al. (2017)
• Association of malignant mesothelioma and asbestos related conditions with ovarian cancer: shared biomarkers and a possible etiological link? — A.J. Rai, R.M. Flores (2011)

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