Positron Emission Tomography/Computed Tomography for the Pleural Staging of Malignant Pleural Mesothelioma: How Accurate Is It?

Our plain-English summary of Positron Emission Tomography/Computed Tomography for the Pleural Staging of Malignant Pleural Mesothelioma: How Accurate Is It?, by V. Pinelli, E. Roca, S. Lucchini, et al (Respiration; International Review of Thoracic Diseases, 2015).

The study

• Authors: V. Pinelli, E. Roca, S. Lucchini, S. Laroumagne, A. Loundou, H. Dutau, F. Maldonado, P. Astoul
• Journal: Respiration; International Review of Thoracic Diseases
• Published: 2015;89(6):558-64
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Careful clinical staging in patients with malignant pleural mesothelioma (MPM) is fundamental in management planning. Positron emission tomography/computed tomography (PET/CT) is increasingly recognized as an important staging modality.

Objectives: The purpose of this study was to assess whether the metabolic activity of the pleural tumor detected with PET/CT correlates with specific endoscopic features and pleural distribution of the lesions as assessed by medical thoracoscopy.

Methods: Consecutive patients with MPM and available PET/CT performed before thoracoscopy were separated into 2 groups, according to their standardized uptake value (SUV). Kaplan-Meier-analysis for survival was performed on groups with low and high SUV. Agreement between PET/CT and thoracoscopy evaluation was analyzed using Cohen's kappa coefficient. The Wilcoxon test was used to compare the median SUV, and the χ(2) test was used to evaluate differences in endoscopic findings.

Results: A total of 32 patients were included. The median maximum SUV (SUV max) was 6.1 and patients were separated into 2 groups based on this cutoff. Patients with SUV max <6.1 had a better survival than those with SUV max ≥6.1 (p = 0.005). The comparison between PET/CT and thoracoscopy showed a fair agreement for visceral and diaphragmatic pleural involvement and moderate agreement for the presence of nodular lesions. There was a statistically significant association between median SUV max and visceral pleural involvement; nodular lesions and visceral pleural involvement were more common in the high-SUV group than in the low-SUV group (p = 0.0012 and p = 0.03, respectively).

Conclusions: PET/CT data may be predictive of thoracoscopic features of MPM associated with prognosis and staging, but the correlation is moderate at best. A degree of disagreement exists between these two modalities, which supports thoracoscopy as the gold standard for assessment of local invasion in MPM.

© 2015 S. Karger AG, Basel.

In plain English

This single-center study in Brescia, Italy, looked back at 32 consecutive patients with malignant pleural mesothelioma, seen from 2006 to 2009, who had a PET/CT scan before medical thoracoscopy (a camera examination inside the chest). The article does not report asbestos exposure. Patients were split at the median maximum tracer uptake on PET/CT (SUV max), 6.1. Median survival was 34.07 months below that value and 12.50 months at or above it (p = 0.005). Median SUV max was higher in the 18 patients whose thoracoscopy showed visceral pleural involvement than in the 14 without it (9.60 versus 5.20, p = 0.032), and in the 19 with nodules than in the 13 without (9.10 versus 4.80, p = 0.009). Agreement between PET/CT and thoracoscopy was fair for visceral and diaphragmatic involvement, moderate for nodules and very poor for pleural thickening. The authors concluded that the correlation is moderate at best and that thoracoscopy remains the gold standard for judging local spread. They noted the study was small and the cutoff arbitrary.

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: Single-center study of consecutive patients identified from an institutional database, comparing PET/CT findings with medical thoracoscopy findings and survival
• Who was studied: 32 consecutive, previously untreated patients with malignant pleural mesothelioma (24 men, 8 women; median age 63, range 45 to 74; 29 epithelioid, 2 mixed, 1 sarcomatoid) at Spedali Civili, Brescia, Italy, 2006 to 2009
• Exposure: No asbestos or fiber exposure is reported. The factor studied was tumor uptake of 18F-FDG on PET/CT (SUV max), with patients split at the median value of 6.1 into low-SUV (below 6.1) and high-SUV (6.1 or above) groups
• Main results:
  • Median survival was 34.07 months in patients with SUV max below 6.1 and 12.50 months in those with SUV max 6.1 or above (p = 0.005)
  • Median SUV max was 9.60 in the 18 patients with visceral pleural involvement at thoracoscopy and 5.20 in the 14 without it (p = 0.032)
  • Median SUV max was 8.00 in the 21 patients with diaphragmatic pleural involvement and 5.00 in the 11 without it; the difference was not statistically significant (p = 0.081)
  • Median SUV max was 9.10 in the 19 patients with nodular lesions and 4.80 in the 13 without nodules (p = 0.009)
  • Agreement between PET/CT and thoracoscopy was fair for visceral pleural involvement (kappa 0.375) and diaphragmatic pleural involvement (kappa 0.313)
  • Agreement was very poor for pleural thickening (kappa -0.188)
  • Agreement was moderate for the presence of nodular lesions (kappa 0.563)
  • Visceral pleural involvement was seen at thoracoscopy in 12 of 16 patients (75%) in the high-SUV group and 6 of 16 (37%) in the low-SUV group
  • Nodular lesions (14 of 16 high-SUV versus 5 of 16 low-SUV) and visceral pleural involvement were more common in the high-SUV group, statistically significant (p = 0.0012 and p = 0.03, respectively)
  • Diaphragmatic pleural involvement was more frequent in the high-SUV group (13 of 16, 81%) than in the low-SUV group (8 of 16, 50%), but not statistically significant (p = 0.06). Pleural thickening was more frequent in the low-SUV group (14 cases, 87%) than in the high-SUV group (11 cases, 68%), not statistically significant (p = 0.08)
• The authors' conclusion: The authors concluded that PET/CT data may predict thoracoscopic features of mesothelioma linked to prognosis and staging, but the correlation is moderate at best, and that the disagreement between the two methods supports thoracoscopy as the gold standard for assessing local invasion
• Limitations the authors state:
  • The study was small, so the results may be hard to generalize to mesothelioma patients at large
  • The SUV cutoff was set arbitrarily at the group's median and may not be clinically relevant

Topics

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

Medical terms in this study, explained in our Lexicon: Staging, Pleural Mesothelioma, Medical Thoracoscopy, Thoracoscopy, Prognosis.

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