Imaging in pleural mesothelioma: a review of imaging research presented at the 9th International Meeting of the International Mesothelioma Interest Group

Our plain-English summary of Imaging in pleural mesothelioma: a review of imaging research presented at the 9th International Meeting of the International Mesothelioma Interest Group, by A.K. Nowak, S.G. Armato, G.L. Ceresoli, et al (Lung Cancer, 2010).

The study

• Authors: A.K. Nowak, S.G. Armato, G.L. Ceresoli, H. Yildirim, R.J. Francis
• Journal: Lung Cancer
• Published: 2010;70(1):1-6
• Type of article: Review
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Imaging of malignant pleural mesothelioma (MPM) poses many challenges for imaging specialists and clinicians due to the anatomic location and unique growth pattern of this tumor. Nevertheless, imaging in MPM plays a critical role in diagnosis, prognostication, prediction or measurement of response to therapy, and monitoring of disease recurrence after aggressive surgical management. Imaging-based studies presented at the 9th International Conference of the International Mesothelioma Interest Group (IMIG) in October 2008 sought to further define the current practice and future potential of imaging for the mesothelioma patient. The Imaging Session was dominated by presentations that addressed the use of fluorodeoxyglucose positron emission tomography (FDG-PET), a clear indication of the expanding role of this modality. These uses included FDG-PET imaging at the point of diagnosis, in prognostication, and in the assessment of response to chemotherapy. Often FDG-PET studies were combined with computed tomography (CT) scans in an attempt to overcome limitations associated with either imaging modality alone. At diagnosis, FDG-PET parameters had a high sensitivity and specificity for differentiation of benign from malignant pleural disease. The use of FDG-PET to extract quantitative features from metabolically active tumor volume was shown to be a significant factor in the prediction of patient survival. The prognostic value of FDG-PET was not confounded by prior talc pleurodesis, despite the inflammatory response associated with the procedure. Metabolic response based on FDG-PET was found to be significantly correlated with progression-free survival. CT-based assessment of mesothelioma was determined to be inconsistent with spherical-model-based criteria so that changes in tumor area, a presumably more complete assessment of tumor burden, exhibited a 46% concordance rate with changes in linear measurements.

Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

In plain English

This article was a review, not a single study. The authors summarized five of the eight imaging presentations on malignant pleural mesothelioma given at the October 2008 International Mesothelioma Interest Group meeting in Amsterdam. Yildirim and colleagues reported on 42 patients: FDG-PET scanning correctly detected malignant disease in 17 of 18 and correctly identified 22 of 24 cases of benign pleural disease. Nowak and colleagues studied newly referred patients, 95% of whom had a history of asbestos exposure. A PET measure called total glycolytic volume was a significant predictor of survival, including in the 28 of 89 patients who had prior talc pleurodesis. Pleurodesis was linked to higher PET values. Ceresoli and colleagues studied 45 patients treated with chemotherapy and found that a response seen on PET was significantly correlated with progression-free survival. Armato and colleagues studied 42 patients. Of 28 judged to have progressive disease by CT tumor thickness, only 13 (46%) also met the area-based threshold. The authors concluded that there is as yet no consensus on, or validation of, PET response criteria, and that CT remains the gold standard for response assessment in clinical trials.

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 summarizing five of the eight oral presentations from the imaging session of the October 2008 International Mesothelioma Interest Group meeting
• Who was studied: Patients with malignant pleural mesothelioma or other pleural disease in four presented studies. Yildirim and colleagues: 42 consecutive patients (18 with mesothelioma, 15 with benign asbestos-related pleural disease, 9 with diffuse pleural fibrosis). Nowak and colleagues: 93 patients accrued from 2003 to 2006 at a single tertiary referral centre, 89 assessable. Ceresoli and colleagues: 45 patients treated with pemetrexed-based chemotherapy. Armato and colleagues: 201 CT scans from 42 patients enrolled in a clinical trial.
• Exposure: Not a study of asbestos exposure. The review concerned imaging methods (FDG-PET and CT). In the cohort reported by Nowak and colleagues, 95% of eligible, assessable patients had a history of asbestos exposure.
• Main results:
  • Yildirim and colleagues (42 patients): FDG-PET correctly detected malignant disease in 17 of 18 patients, with a sensitivity of 94.4%, specificity of 91.7% and accuracy of 92.3%.
  • Yildirim and colleagues: malignant lesions took up significantly more FDG than benign lesions (mean SUV 7.8 versus 0.4, p less than 0.001). In this group, an SUV cut-off of 3.0 gave 100% sensitivity and specificity.
  • Nowak and colleagues (89 assessable patients, 72 deaths over a median follow-up of 18.6 months): on univariate analysis, total glycolytic volume (TGV) on FDG-PET was a significant prognostic factor (p = 0.003).
  • Nowak and colleagues: when patients with sarcomatoid disease were excluded, high baseline TGV was more predictive of survival than the EORTC prognostic score, both in patients with previous pleurodesis (Harrell's C = 0.71, HR 1.77, p = 0.05) and in patients without it (Harrell's C = 0.67, HR 1.22, p = 0.0009).
  • Van der Schaaf, Francis and colleagues (same cohort; 28 of 89 had prior pleurodesis): the pleurodesis group had significantly higher TGV than the non-pleurodesis group (mean 1796 versus 506, p = 0.003) and higher SUVmax (9.1 versus 6.7, p = 0.02).
  • Van der Schaaf, Francis and colleagues: baseline TGV remained an independent prognostic factor in both pleurodesed patients (HR = 1.54, p = 0.01) and non-pleurodesed patients (HR = 1.25, p = 0.018).
  • Van der Schaaf, Francis and colleagues: CT TNM stage predicted survival in the non-pleurodesis group (p = 0.04) but not in patients with prior pleurodesis (p = 0.14).
  • Ceresoli and colleagues (45 patients): metabolic response was significantly correlated with progression-free survival, HR 2.60 (95% CI 1.27 to 5.20, p less than 0.001) for SUVmax and HR 2.80 (95% CI 1.46 to 5.36, p = 0.001) for TGV.
  • Ceresoli and colleagues: for overall survival, HR 2.61 (95% CI 1.19 to 5.73, p = 0.024) for SUVmax and HR 2.41 (95% CI 1.20 to 4.85, p = 0.009) for TGV.
  • Ceresoli and colleagues: in the 33 patients without prior talc pleurodesis, the link between TGV change and overall survival was not statistically significant (p = 0.083).
  • Armato and colleagues (201 CT scans from 42 patients): of 28 patients classed as having progressive disease by a 20% or greater change in summed tumor thickness, only 13 (46%) showed a change in summed tumor area above the expected 44% threshold.
• The authors' conclusion: The authors concluded that FDG-PET is likely to be useful in assessing response, but there is as yet no consensus on, or validation of, FDG-PET response criteria for malignant pleural mesothelioma. They also concluded that CT remains the gold standard for response assessment in clinical trials.
• Limitations the authors state:
  • The authors stated that the Yildirim findings require further validation in larger, multicentre series.
  • The authors stated that the broader applicability of the Nowak prognostic findings must be tested by using the algorithm at other centres.
  • The authors stated that further studies are needed to define the optimal PET response criteria.
  • The authors stated that the impact of pleurodesis on PET-based response assessment and prognosis remains unresolved.
  • The review covered only five of the eight presentations from the session.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Mesothelioma, IMIG, Chemotherapy, Talc Pleurodesis, Progression-Free Survival, Tumor Burden.

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• Imaging in pleural mesothelioma: A review of the 14th International Conference of the International Mesothelioma Interest Group — S.G. Armato, R.J. Francis, et al. (2019)
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• Imaging in pleural mesothelioma: A review of the 13th International Conference of the International Mesothelioma Interest Group — S.G. Armato, K.G. Blyth, et al. (2016)
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• The role of surgical cytoreduction in the treatment of malignant pleural mesothelioma: meeting summary of the International Mesothelioma Interest Group Congress, September 11-14, 2012, Boston, Mass — V. Rusch, E.H. Baldini, et al. (2013)

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