Integrated positron emission tomography-computed tomography does not accurately stage intrathoracic disease of patients undergoing trimodality therapy for malignant pleural mesothelioma

Our plain-English summary of Integrated positron emission tomography-computed tomography does not accurately stage intrathoracic disease of patients undergoing trimodality therapy for malignant pleural mesothelioma, by J. Pilling, J.A. Dartnell, L. Lang-Lazdunski (The Thoracic and Cardiovascular Surgeon, 2010).

The study

• Authors: J. Pilling, J.A. Dartnell, L. Lang-Lazdunski
• Journal: The Thoracic and Cardiovascular Surgeon
• Published: 2010;58(4):215-9
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: The results of trimodality therapy for malignant pleural mesothelioma (MPM) are related to stage. Staging can be carried out by computed tomography (CT), magnetic resonance imaging and fluorodeoxyglucose positron emission tomography (FDG-PET), but all modalities suffer from limitations. We investigated whether integrated PET-CT improved the intrathoracic staging of patients undergoing trimodality therapy for MPM.

Methods: Twenty consecutive patients [18 male, median age 62 years (range 52-68)] who underwent 24 PET-CT scans prior to extrapleural pneumonectomy (EPP) as part of trimodality therapy for MPM were reviewed. The intrathoracic stage of MPM on PET-CT was compared with the pathological stage following examination of the resected specimen. Patients excluded from radical surgery due to metastatic disease were not studied here.

Results: PET-CT was performed a median of 119 days (range 2-229) prior to EPP. 16 scans were performed after talc pleurodesis. Nine scans were performed following chemotherapy. PET-CT correctly identified the T stage in 3 patients, overstaged 4 and understaged 17. Six scans failed to identify disease that later proved to be pT4. Nine patients were found to have pN2 disease; PET-CT identified N2 disease with a sensitivity of 11.1 %, specificity of 93 % and accuracy of 66 %. Previous talc pleurodesis did not alter the accuracy of PET-CT staging.

Conclusions: In one of the few studies of integrated PET-CT in MPM that has complete pathological correlation we have shown that PET-CT does not accurately identify advanced tumor stage (T4) or mediastinal nodal disease (N2). The role of PET-CT staging prior to EPP lies outside the affected hemithorax.

In plain English

This retrospective study tested how well integrated FDG PET-CT scanning staged malignant pleural mesothelioma inside the chest. The authors reviewed 20 consecutive patients (18 male, median age 62) who had trimodality therapy, including extrapleural pneumonectomy, between April 2004 and August 2008. Their 24 PET-CT scans were compared with the stage found when the removed tissue was examined. PET-CT staged the tumor correctly on 3 scans, overstaged 4 and understaged 17. Five patients had T4 disease on pathology, and none of their six scans identified it. Nine patients had N2 disease (spread to lymph nodes in the middle of the chest on the same side). PET-CT noted it on only one scan, giving a reported sensitivity of 11.1%, specificity of 93% and accuracy of 66.6%. Nodal staging accuracy did not differ significantly between scans done after talc pleurodesis and scans done without it. The authors concluded that PET-CT does not accurately identify T4 or N2 disease and that mediastinoscopy remains necessary. They noted that the study was retrospective and that some scans were done months before surgery or after chemotherapy.

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: Retrospective review comparing staging by integrated PET-CT with pathological staging of the surgically removed tissue (diagnostic accuracy study)
• Who was studied: 20 consecutive patients (18 male, median age 62, range 52 to 68) with malignant pleural mesothelioma (7 biphasic, 13 epithelioid) who underwent trimodality therapy between April 2004 and August 2008. They had 24 PET-CT scans before extrapleural pneumonectomy. Patients excluded from surgery because of disease outside the chest were not included.
• Exposure: Not an asbestos exposure study. The test examined was integrated FDG PET-CT scanning used for staging before surgery. 16 of the 24 scans were done after talc pleurodesis and 9 after chemotherapy.
• Main results:
  • T stage (24 scans): PET-CT was correct on 3 scans, overstaged 4 and understaged 17.
  • Five patients had pathological T4 disease (two with aortic invasion, three with full thickness pericardial involvement). None of their six PET-CT scans identified T4 disease.
  • Nine patients had pathological N2 disease. PET-CT noted N2 disease on only one scan.
  • For N2 disease, the article reports a PET-CT sensitivity of 11.1%, specificity of 93% and accuracy of 66.6%.
  • Mediastinal nodal staging was correct on 8 of 16 scans done after talc pleurodesis and on 5 of 8 scans done without talc (p = 0.33).
  • Contralateral mediastinal nodal involvement seen on PET-CT proved on biopsy to be anthracosis (a benign finding).
• The authors' conclusion: The authors concluded that PET-CT does not accurately identify advanced tumor stage (T4), that it has a sensitivity of only 11.1% for mediastinal nodal disease (N2), and that mediastinoscopy remains necessary to stage patients being considered for extrapleural pneumonectomy.
• Limitations the authors state:
  • Because the study worked back from patients who had surgery, it cannot determine how useful PET-CT is across all patients considered for radical surgery or other treatment.
  • Some scans were done up to seven months before surgery, and the disease may have progressed in the meantime.
  • Nine of the 24 scans were done after chemotherapy, which can change how tumors take up the tracer.
  • The study was retrospective, so the authors could not control for confounding factors.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Intrathoracic, Trimodality Therapy, Pleural Mesothelioma, Staging, PET-CT, Extrapleural Pneumonectomy (EPP), Talc Pleurodesis, Chemotherapy.

Related studies

• Role of integrated 18-fluorodeoxyglucose position emission tomography-computed tomography in patients surveillance after multimodality therapy of malignant pleural mesothelioma — C. Tan, S. Barrington, et al. (2010)
• Clinical value of fluorodeoxyglucose-positron emission tomography/computed tomography in differentiation of malignant mesothelioma from asbestos-related benign pleural disease: an observational pilot study — H. Yildirim, M. Metintas, et al. (2009)
• Patterns of disease progression on 18F-fluorodeoxyglucose positron emission tomography-computed tomography in patients with malignant pleural mesothelioma undergoing multimodality therapy with pleurectomy/decortication — A. Bille, S. Chicklore, et al. (2013)
• 18-Fluorodeoxyglucose positron emission tomography as a tool for response prediction in solid tumours — D.J. De Maeseneer, B. Lambert, et al. (2010)
• Does positron emission tomography offer prognostic information in malignant pleural mesothelioma? — S. Sharif, I. Zahid, et al. (2011)
• Clinical implications of 18F-fluorodeoxyglucose positron emission tomography/computed tomography at delayed phase for diagnosis and prognosis of malignant pleural mesothelioma — Y. Abe, K. Tamura, et al. (2012)

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