Should uncertainty concerning the risk of malignancy be included in diagnostic (nongynecologic) cytopathology reports?

Our plain-English summary of Should uncertainty concerning the risk of malignancy be included in diagnostic (nongynecologic) cytopathology reports?, by D.N. Poller, F. Schmitt (Cancer Cytopathology, 2021).

The study

• Authors: D.N. Poller, F. Schmitt
• Journal: Cancer Cytopathology
• Published: 2021;129(1):16-21
• Type of article: Review
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In diagnostic cytology, the known site-specific false positive rates at various anatomical sites for the risk malignancy (ROM) when a confirmed malignant diagnosis is made are comparatively well documented. ROM figures for diagnostic cytology specimens may vary according to the anatomical site of the specimen, the exact nature of the specimen received, the staining method(s) used, and the use of additional laboratory techniques including molecular profiling; furthermore, they often differ to some extent from institution to institution, between differing cytologists within the same institution, and over time. A brief literature review for a selected group of routine diagnostic cytology specimens shows a published ROM for a confirmed malignant diagnosis as follows: bile duct brushings, ~99% (range, 97%-100%); breast fine needle aspiration, 98.5% (range, 92%-100%); serous effusion fluid, 98.9% (range, 90%-100% although lower for squamous cell carcinoma, mesothelioma, and lymphoma), pulmonary endobronchial ultrasound cytology, ~99% (range, 86.6%-100%); thyroid FNA, 98% (range, 97%-99% if NIFTP tumors are excluded), salivary gland FNA, ~90%; (range 57%-100%) and lateral neck cyst FNA, ~99% (range, 95.5%-100%). Because most diagnostic cytology specimens have a small but accepted false-positive rate, this information is vitally important for the clinical management of patients and for shared patient decision making. In our view, the known false-positive rate for a given diagnostic cytology specimen could be included within the cytology report to assist in explaining the limitations of the diagnostic cytology interpretation and help facilitate the clinical decision-making process.

© 2020 The Authors. Cancer Cytopathology published by Wiley Periodicals LLC on behalf of American Cancer Society.

In plain English

This was a brief review and opinion article by two pathologists. It looked at published figures for how often a 'malignant' result on cytology (tests that examine loose cells from fluid, brushings or needle samples) is truly cancer. This is called the risk of malignancy. The article covered thyroid, salivary gland, lateral neck cyst, bile duct, pleural fluid, lung and breast samples. Figures quoted from other studies included a mean risk of malignancy of 98.9% for serous effusion fluids and 91% for salivary gland needle samples. For pleural fluid, the authors wrote that cytology is less helpful for some cancers, including mesothelioma, because the cell features of malignant mesothelioma overlap with benign reactive pleural changes. They cited a survey in which 37% of respondents said clinicians at their institution would not treat definitively on a cytology diagnosis of malignant mesothelioma. The authors concluded that the known false-positive rate could be included in cytology reports, and they saw a particular case for this in suspected malignant mesothelioma. They noted that published figures vary considerably and may not reflect an individual laboratory's own practice.

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 and opinion article (brief literature review)
• Who was studied: Published literature on a selected group of routine nongynecologic cytology specimens: thyroid, salivary gland, lateral neck cyst, bile duct brushing, pleural and other serous effusion fluid, lung/endobronchial ultrasound, and breast samples
• Exposure: No exposure was studied. The article concerns the accuracy of malignant diagnoses on cytology specimens. Asbestos is not mentioned.
• Main results:
  • A meta-analysis cited by the authors (Farahani and Baloch) reported a mean risk of malignancy of 98.9% for all serous effusion fluids, and 99.2% in 31 studies of pleural fluid cytology
  • The authors stated that pleural effusion cytology is less helpful for some subtypes, including mesothelioma, because the cytological features of malignant mesothelioma overlap with benign reactive pleural changes
  • In a survey cited by the authors, 37% of respondents said clinicians at their own institution would not treat a patient definitively based on a cytological diagnosis of malignant mesothelioma in an effusion fluid or needle aspirate
  • The authors saw a case for including a false-positive statement in reports of suspected malignant mesothelioma or suspected lymphoma, but possibly not for adenocarcinoma on pleural fluid
  • Figures cited from other studies for other sites: thyroid needle samples, risk of malignancy 97% to 99% (excluding NIFTP tumors), implying a 1% to 3% false-positive rate
  • Salivary gland needle samples: a cited meta-analysis of 92 studies with 16,546 samples found a 91% risk of malignancy
  • Endobronchial ultrasound cytology: one cited study (Layfield et al) reported a risk of malignancy of 87%
  • Breast needle samples: the cited literature gives a positive predictive value averaging 98.5%, with a range of 92% to 100%
• The authors' conclusion: The authors concluded that the known site-specific risks of false-positive malignant results could be included in cytology reports, to communicate uncertainty to clinicians and patients
• Limitations the authors state:
  • Published risk-of-malignancy figures vary considerably between reports
  • Published figures may not reflect an individual laboratory's or institution's own practice
  • The views are the personal views of the authors

Topics

Medical terms in this study, explained in our Lexicon: Cytopathology, Cytology, Molecular Profiling, Squamous Cell Carcinoma, Mesothelioma, Ultrasound.

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• Asbestos-related malignancy — K.H. Antman (1986)
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