Preoperative prediction of unresectability in malignant pleural mesothelioma

Our plain-English summary of Preoperative prediction of unresectability in malignant pleural mesothelioma, by B.M. Burt, H.S. Lee, A.C. Raghuram, et al (The Journal of Thoracic and Cardiovascular Surgery, 2020).

The study

• Authors: B.M. Burt, H.S. Lee, A.C. Raghuram, C. Strange, J. Mason, T. Strange, J. Delgado, D.J. Sugarbaker
• Journal: The Journal of Thoracic and Cardiovascular Surgery
• Published: 2020;159(6):2512-2520.e1
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: Diffuse chest wall invasion (DCWI) is a common finding in patients undergoing intended resection for malignant pleural mesothelioma. We sought to determine the incidence and preoperative predictors of this finding, and to test our anecdotal impression that contraction of the ipsilateral hemithorax is associated with DCWI.

Methods: This was a single-institution retrospective study of 170 patients undergoing intended macroscopic complete resection for malignant pleural mesothelioma from 2014-2018. A novel metric of thoracic cage volume was calculated by preoperative chest computed tomography. Univariable analyses were performed to determine associations of preoperative variables with DCWI.

Results: Macroscopic complete resection was achieved by pleurectomy/decortication in 104 patients (61%) and by extrapleural pneumonectomy in 39 patients (23%). Unresectable disease was discovered at thoracotomy in 27 (16%) of patients; 24 (14%) by DCWI and 3 (2%) by intrathoracic organ invasion. In univariable analysis, decreased ipsilateral thoracic cage volume demonstrated the strongest association with unresectability by DCWI (P = .009) with >5% decrease in thoracic cage volume representing the optimal cutoff (P = .014; area under the curve, 0.67). Other preoperative variables associated with DCWI included preoperative chest pain requiring opioids (P = .028), prior pleurodesis (P = .036), decreased forced vital capacity (P = .023), decreased ipsilateral lung perfusion by ventilation/perfusion lung scan (P = .007), and magnetic resonance imaging findings of chest wall invasion (P = .035).

Conclusions: Preoperative identification of DCWI will avoid unnecessary thoracotomy and accelerate initiation of nonsurgical therapy in malignant pleural mesothelioma. Our data suggest that contraction of thoracic cage volume has merit in predicting malignant pleural mesothelioma unresectability and should be validated in prospective studies.

Copyright © 2019 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

In plain English

This single-institution retrospective study looked at 170 patients with malignant pleural mesothelioma who had surgery in 2014-2018 intended to remove all visible tumor. The article does not address asbestos exposure. Complete removal of visible tumor was achieved in 104 patients by pleurectomy/decortication and in 39 by extrapleural pneumonectomy. In 27 patients (15.9%), the tumor was found to be unremovable during the operation: 24 because of diffuse chest wall invasion and 3 because of invasion of other chest structures. The authors used preoperative CT scans to compare the chest cage volume on the tumor side with the opposite side. A smaller chest cage on the tumor side was associated with diffuse chest wall invasion. The best cutoff was a tumor side more than 5% smaller than the opposite side, with 75% sensitivity and 57% specificity. Opioid-requiring chest pain, prior pleurodesis, lower lung function and MRI signs of chest wall invasion were also associated. The authors concluded that thoracic cage volume has merit in predicting unresectability and should be tested in prospective studies. They noted that the retrospective design and their high-volume center may limit the findings.

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-institution retrospective study using a prospectively maintained database, with univariable analyses
• Who was studied: 170 patients with malignant pleural mesothelioma who underwent thoracotomy intended to achieve macroscopic complete resection, at Baylor College of Medicine (Houston), 2014 to 2018
• Exposure: Asbestos exposure was not reported. The factors studied were preoperative clinical, lung-function and imaging variables. The main one was a new CT-based measure of thoracic cage volume, comparing the tumor-bearing half of the chest with the opposite half.
• Main results:
  • Macroscopic complete resection was achieved in 39 patients (22.9%) by extrapleural pneumonectomy and in 104 patients (61.2%) by pleurectomy/decortication.
  • 27 patients (15.9%) had only an exploratory thoracotomy because the disease was unresectable. Of these, 24 (89%) had diffuse chest wall invasion and 3 had invasion of intrathoracic organs or mediastinal structures.
  • Percentage change in chest volume (tumor side compared with opposite side) was associated with unresectability by diffuse chest wall invasion: odds ratio 0.91 (95% confidence interval 0.85-0.98), P = .009.
  • The optimal cutoff was a 5% decrease in thoracic cage volume on the tumor side compared with the opposite side (area under the curve 0.67, P = .014). At this cutoff, sensitivity was 75%, specificity 57% and accuracy 60% for predicting unresectability by diffuse chest wall invasion.
  • Other preoperative factors associated with diffuse chest wall invasion in univariable analysis were chest pain requiring opioids (odds ratio 3.12, 1.13-8.62), prior pleurodesis (2.56, 1.07-6.16), MRI chest wall invasion (2.66, 1.07-6.62), forced vital capacity (0.97, 0.94-0.99) and ipsilateral lung perfusion (0.95, 0.91-0.99).
  • 140 patients had a preoperative MRI. For predicting diffuse chest wall invasion, MRI signs of chest wall invasion had sensitivity of 52%, specificity of 70% and accuracy of 67%.
  • Change in thoracic cage volume was not correlated with ipsilateral lung perfusion (R 0.077, P = .367).
• The authors' conclusion: The authors concluded that contraction of thoracic cage volume has merit in predicting unresectability of malignant pleural mesothelioma and should be validated in prospective studies.
• Limitations the authors state:
  • The retrospective design brings inherent biases, including selection bias and unmeasured confounders.
  • The results come from a high-volume mesothelioma center and may not be generalizable.
  • Not all CT scans were done on the same machine or at the same institution; some were outside studies.
  • The volume measurement could be affected by scoliosis, chest wall deformities and patient position in the scanner.
  • Volumes were measured by a single radiologist, so variability between radiologists still needs study.

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: Pleural Mesothelioma, Hemithorax, Pleurectomy/Decortication (P/D), Extrapleural Pneumonectomy (EPP), Unresectable, Thoracotomy, Intrathoracic, Pleurodesis.

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