Clinical staging of malignant pleural mesothelioma: current perspectives

Our plain-English summary of Clinical staging of malignant pleural mesothelioma: current perspectives, by M. Bonomi, C. De Filippis, E. Lopci, et al (Lung Cancer, 2017).

The study

• Authors: M. Bonomi, C. De Filippis, E. Lopci, L. Gianoncelli, G. Rizzardi, E. Cerchiaro, L. Bortolotti, A. Zanello, G.L. Ceresoli
• Journal: Lung Cancer
• Published: 2017;8:127-139
• Type of article: Review
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is a disease with limited therapeutic options, the management of which is still controversial. Diagnosis is usually made by thoracoscopy, which allows multiple biopsies with histological subtyping and is indicated for staging purposes in surgical candidates. The recommended and recently updated classification for clinical use is the TNM staging system established by the International Mesothelioma Interest Group and the International Association for the Study of Lung Cancer, which is based mainly on surgical and pathological variables, as well as on cross-sectional imaging. Contrast-enhanced computed tomography is the primary imaging procedure. Currently, the most used measurement system for MPM is the modified Response Evaluation Criteria in Solid Tumors (RECIST) method, which is based on unidimensional measurements of tumor thickness perpendicular to the chest wall or mediastinum. Magnetic resonance imaging and functional imaging with 18F-fluoro-2-deoxy-D-glucose positron-emission tomography can provide additional staging information in selected cases, although the usefulness of this method is limited in patients undergoing pleurodesis. Molecular reclassification of MPM and gene expression or miRNA prognostic models have the potential to improve prognostication and patient selection for a proper treatment algorithm; however, they await prospective validation to be introduced in clinical practice.

In plain English

This review of published literature on diagnosing and staging malignant pleural mesothelioma, by authors at hospitals in Bergamo and Milan, Italy, did not study asbestos exposure. Asbestos appeared in scan descriptions, in a reviewed study comparing mesothelioma with benign asbestos pleurisy, and in a note that another tumor may be related to asbestos exposure. The review described the eighth edition of the TNM staging system, which regrouped tumor and lymph-node categories, and called contrast-enhanced chest CT the imaging method of choice. A cited study found MRI more accurate than CT for invasion of the chest wall and endothoracic fascia (69% vs 46%) and diaphragm (82% vs 55%). For telling malignant from benign pleural disease, PET accuracy varied from 91% to 98%. Staging results varied more, with one study reporting 32% overall lymph-node accuracy. The review reported calcified pleural plaques on CT in 20% of patients and said talc pleurodesis causes increased PET uptake that can persist for an unpredictable period. The authors concluded that molecular and gene-based prognostic models seem promising but need validation in large prospective series.

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 on clinical staging of malignant pleural mesothelioma
• Who was studied: No patients were studied directly. The authors, from hospitals in Bergamo and Milan, Italy, reviewed published studies of patients with malignant pleural mesothelioma.
• Exposure: Asbestos exposure was not studied. Asbestos-related pleural disease is mentioned as a possible imaging finding and as a comparison group in one cited PET/CT study. The review also describes one other tumor in the differential diagnosis as possibly related to asbestos exposure.
• Main results:
  • The review described the main changes in the eighth edition of the TNM classification for malignant pleural mesothelioma. T1a and T1b were grouped into T1, N1 and former N2 were grouped into a new N1, and former N3 nodes were classified as N2.
  • The review described contrast-enhanced chest CT as the imaging method of choice for malignant pleural mesothelioma.
  • Citing an earlier study, the review reported that thoracic MRI was more accurate than CT for identifying invasion of the chest wall and endothoracic fascia (69% vs 46%) and diaphragmatic invasion (82% vs 55%).
  • For FDG PET used to tell malignant lesions from benign pleural disease, the review summarized the accuracy of the method as varying from 91% to 98%.
  • For staging, results were more variable. In one cited PET/CT study of 29 patients being considered for extrapleural pneumonectomy, overall lymph-node (N) accuracy was 32%.
  • One cited PET/CT diagnostic study included 31 people: 17 with malignant pleural mesothelioma, nine with benign asbestos pleurisies and five with pleural fibrosis.
  • The review stated that calcified pleural plaques, representing asbestos-related pleural disease, are observed on CT in 20% of patients with malignant pleural mesothelioma. It added that they should not be mistaken for bone or cartilage formation within the tumor.
  • The review stated that talc pleurodesis causes markedly increased FDG uptake on PET, which can persist for an unpredictable period.
  • Among the prognostic models reviewed, histology (epithelioid vs nonepithelioid) remained the most significant predictor.
  • The review stated that a diagnosis of malignant pleural mesothelioma must still rely on tissue (histopathological) confirmation.
• The authors' conclusion: The authors concluded that molecular reclassification of malignant pleural mesothelioma and gene-expression or miRNA prognostic models seem promising, but that their results still need to be validated in large prospective series.

Topics

Medical terms in this study, explained in our Lexicon: Staging, Pleural Mesothelioma, Thoracoscopy, TNM Staging, Mesothelioma, Lung Cancer, Modified RECIST (mRECIST), Mediastinum.

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