Surgical assessment of malignant pleural mesothelioma: have we reached a critical stage?

Our plain-English summary of Surgical assessment of malignant pleural mesothelioma: have we reached a critical stage?, by A. Nakas, E. Black, J. Entwisle, et al (European Journal of Cardio-thoracic Surgery, 2010).

The study

• Authors: A. Nakas, E. Black, J. Entwisle, S. Muller, D.A. Waller
• Journal: European Journal of Cardio-thoracic Surgery
• Published: 2010;37(6):1457-63
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The International Mesothelioma Interest Group (IMIG) classification is the most widely used staging system but is based on post-resectional parameters. We aimed to test the association between clinical and pathological staging and to identify possible discrepancies.

Methods: We identified 164 consecutive patients (144 males and 20 females, with mean age 58 years) who underwent radical surgery (114 extrapleural pneumonectomy; 50 radical pleurectomy/decortication) for malignant pleural mesothelioma (MPM). The patients were clinically staged with CT + or - MRI (CT, computed tomography; MRI, magnetic resonance imaging).

Results: Clinical T (cT) stage proved to be the same as pathological T (pT) stage in 44%; understaged in 46% and overstaged in 10%. Clinical N (cN) stage proved to be the same as pathological N (pN) stage in 56%; understaged in 31% and overstaged in 13%. Disease-free interval (DFI) was associated with cT stage (median DFI 29 months, SE 13, 95% CI 3-54 months for cT1; median 5, SE 3, 95% CI 3-6 months for cT4, p=0.02) but not clinical N stage (median DFI 12 months, SE 1, 95% CI 9-15 months for cN0; median DFI 11 months, SE 0.3, 95% CI 10-12 months for cN2, p=0.5) and was associated with both pT (median DFI 31 months, SE 17, 95% CI 0-64 months for pT1; median DFI 8 months, SE1, 95% CI 6-11 months for pT4, p=0.03) and pN stage (median DFI 14 months, SE 3, 95% CI 9-20 months for pN0; median DFI 10 months, SE 1, 95% CI 8-13 months for pN2, p=0.02). Overall survival was associated with cT stage (median survival 25 months, SE 3, 95% CI 20-30 months for cT1; median survival 11 months, SE 3, 95% CI 10-11 months for cT4, p=0.01) but not cN stage (median survival 15 months, SE 2, 95% CI 11-19 months for cN0; median survival 15 months, SE 2, 95% CI 12-19 months for cN2, p=0.49) and pN stage (median survival 22 months, SE 3, 95% CI 19-27 months for pN0; median survival 14 months, SE 1, 95% CI 12-17 months for pN2, p=0.01) but not pT stage (median survival 27 months, SE 4, 95% CI 19-35 months for pT1; median survival 12 months, SE 2, 95% CI 9-15 months for pT4, p=0.06). Pathological IMIG stage was associated with DFI and overall survival; however, preoperative IMIG stage was less useful.

Conclusions: There are deficiencies in the current staging system for MPM and discrepancies between clinical and pathological systems. Future improvements are needed in clinical descriptors of nodal status and pathological descriptors of T stage. Subsequent IMIG stage grouping also needs revision.

Copyright 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

In plain English

This retrospective study from two UK surgical departments included 164 of 207 patients who had radical surgery for malignant pleural mesothelioma over 9 years. These patients had full staging data. The authors compared stage estimated before surgery from CT (MRI in selected cases) with stage found by pathologists afterwards, using the International Mesothelioma Interest Group (IMIG) system. Asbestos exposure is not reported. Preoperative staging matched pathological tumour (T) stage in 44% of patients and underestimated it in 46%. It matched lymph node (N) stage in 56% and underestimated it in 31%. Higher clinical T stage was associated with shorter time to progression and shorter survival (median 25 months, 95% CI 20 to 30, for cT1 versus 11 months, 95% CI 10 to 11, for cT4; p = 0.01). Clinical N stage was associated with neither. Pathological N and IMIG stages were associated with survival. Survival did not differ significantly across pathological T stages (p = 0.06). The authors concluded that the staging system has deficiencies and needs revision. They noted the retrospective design, small numbers, and exclusion of 43 patients with incomplete data.

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 study of a surgical case series, comparing clinical (imaging-based) and pathological staging, with Kaplan-Meier survival analysis
• Who was studied: 164 patients (144 males, 20 females, mean age 57.6 years, range 14 to 75) with malignant pleural mesothelioma. They were drawn from 207 consecutive patients who had radical surgery over 9 years in two surgical departments, and were the ones with full staging data. 120 had epithelioid, 39 biphasic and 5 sarcomatoid disease. 114 had extrapleural pneumonectomy and 50 had radical pleurectomy/decortication.
• Exposure: No asbestos exposure was studied. The comparison was between clinical staging from CT of the thorax and abdomen (MRI in selected cases only) and pathological staging after radical surgery, using the IMIG TNM system.
• Main results:
  • T stage: clinical and pathological T stage were the same in 44% of patients. Clinical staging underestimated T stage in 46% and overestimated it in 10%.
  • N stage: clinical and pathological N stage were the same in 56% of cases. Clinical staging underestimated N stage in 31% and overestimated it in 13%.
  • IMIG stage grouping: pathological stage was the same as clinical stage in 44.5% of patients. Clinical staging understaged the disease in 44.5% and overstaged it in 11%.
  • The rate of positive (R1/2) resection margins rose with clinical T stage, from 17.6% in cT1 to 66.7% in cT4 (p = 0.007). It rose with pathological T stage from 15.4% in pT1 to 66.7% (p = 0.005).
  • Clinical N stage (p = 0.75), pathological N stage (p = 0.61) and clinical IMIG stage (p = 0.08) were not associated with positive margins. Pathological IMIG stage was associated with them (p = 0.004).
  • No clinical or pathological T, N or IMIG stage was associated with the incidence or pattern of recurrence (all p values above 0.3).
  • Disease-free interval, among 146 patients (deaths within 90 days excluded): it fell with clinical T stage, from a median of 29 months for cT1 to 5 months for cT4 (p = 0.02). Clinical N stage was not associated (p = 0.5). The clinical IMIG result (29 to 8 months) did not reach statistical significance (p = 0.08).
  • Disease-free interval fell with pathological stage: from 31 months for pT1 to 8 months for pT4 (p = 0.03), from 14 months for pN0 to 10 months for pN2 (p = 0.02), and from 31 months for pIMIG I to 8 months for pIMIG IV (p = 0.03).
  • Overall survival fell with clinical T stage, from a median of 25 months (95% CI 20 to 30) for cT1 to 11 months (95% CI 10 to 11) for cT4 (p = 0.01). Clinical N stage was not associated with survival (p = 0.5). Clinical IMIG stage narrowly reached statistical significance (25 months for stage I to 11 months for stage IV, p = 0.05).
  • Median survival fell from 27 months for pT1 to 12 months for pT4, but the difference between pT stages was not statistically significant (p = 0.06).
  • Median survival fell from 22 months for pN0 to 14 months for pN2 (p = 0.01), and from 27 months for pIMIG I to 12 months for pIMIG IV (p = 0.03).
• The authors' conclusion: The authors concluded that there are deficiencies in the current staging system for malignant pleural mesothelioma and discrepancies between clinical and pathological staging. In their view, clinical descriptors of nodal status and pathological descriptors of T stage need improvement, and IMIG stage grouping needs revision.
• Limitations the authors state:
  • Retrospective study with relatively small numbers, especially in the early-stage groups
  • Data were incomplete for 43 patients (reported as 25%), who were excluded
  • Confounding factors such as trimodality treatment (chemotherapy and radiotherapy added to surgery) were not analysed
  • In the conference discussion, the author said the outcome of the excluded patients is unknown and that the study was not a consecutive case series

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, Staging, Extrapleural Pneumonectomy (EPP), Pleurectomy/Decortication (P/D), Overall Survival, Median Overall Survival.

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• Integrated positron emission tomography-computed tomography does not accurately stage intrathoracic disease of patients undergoing trimodality therapy for malignant pleural mesothelioma — J. Pilling, J.A. Dartnell, et al. (2010)
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• Impact of induction therapy on postoperative outcome after extrapleural pneumonectomy for malignant pleural mesothelioma: does induction-accelerated hemithoracic radiation increase the surgical risk? — P. Mordant, K. McRae, et al. (2016)
• What is the best way to diagnose and stage malignant pleural mesothelioma? — I. Zahid, S. Sharif, et al. (2011)

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