Radiological evaluation of malignant pleural mesothelioma - defining distant metastatic disease

Our plain-English summary of Radiological evaluation of malignant pleural mesothelioma - defining distant metastatic disease, by D.C. Collins, R. Sundar, A. Constantinidou, et al (BMC Cancer, 2020).

The study

• Authors: D.C. Collins, R. Sundar, A. Constantinidou, D. Dolling, T.A. Yap, S. Popat, M.E. O'Brien, U. Banerji, J.S. de Bono, J.S. Lopez, N. Tunariu, A. Minchom
• Journal: BMC Cancer
• Published: 2020;20(1):1210
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant pleural mesothelioma (MPM) is traditionally characterized by local destructive spread of the pleura and surrounding tissues. Patient outcomes in MPM with distant metastatic dissemination are lacking.

Methods: In this retrospective study, we reviewed a cohort of 164 MPM patients referred to a Phase I trials unit, aiming to describe identified metastatic sites, and correlate with clinical outcomes.

Results: 67% of patients were diagnosed with distant metastatic disease with a high incidence of bone (19%), visceral (14%), contralateral lung (35%) and peritoneal metastases (22%). Peritoneal metastases were more likely in epithelioid versus biphasic/ sarcomatoid MPM (p = 0.015). Overall survival was 23.8 months with no statistical difference in survival between those with distant metastases and those without.

Conclusions: This report highlights the frequency of distant metastases and encourages further radiological investigations in the presence of symptoms. In particular, given the relatively high incidence of bone metastases, bone imaging should be considered in advanced MPM clinical workflow and trial protocols. The presence of distant metastases does not appear to have prognostic implications under existing treatment paradigms. This cohort of MPM patients gives an indication of patterns of metastatic spread that are likely to become prevalent as prognosis improves with emerging treatment paradigms.

In plain English

This retrospective study reviewed records of 164 patients with malignant pleural mesothelioma. All had been referred to an early phase clinical trials unit at the Royal Marsden Hospital and Institute of Cancer Research in the UK between January 1992 and January 2017. A single radiologist reviewed the available imaging to find where the cancer had spread. Of the 164 patients, 110 (67%) had at least one documented site of distant spread. These included the opposite lung in 55 (35%), the peritoneum or omentum in 36 (22%), bone in 31 (19%), abdominal organs such as the liver in 23 (14%) and the brain in 5 (3%). Peritoneal spread was more frequent in epithelioid tumours (27.0%) than in biphasic or sarcomatoid tumours (4.3%). Median overall survival was 23.8 months, and epithelioid tumours had better survival. Distant spread did not correlate with overall survival. The study did not report patients' asbestos exposure. The authors concluded that advanced pleural mesothelioma should no longer be considered a local disease without the propensity to spread, and that bone imaging should be considered. They noted the study was retrospective and that some metastases may have gone undetected.

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 of patients from a prospectively maintained database at a single early phase trials unit
• Who was studied: 164 patients with malignant pleural mesothelioma referred to the Drug Development Unit (Royal Marsden Hospital/Institute of Cancer Research, London, UK) for possible early phase clinical trials, January 1992 to January 2017, with follow-up to January 2018; 76% male, median age at diagnosis 64 years
• Exposure: Not studied. The article examined sites of cancer spread on imaging and survival, not asbestos exposure or fiber types
• Main results:
  • 110 of 164 patients (67%) had at least one documented site of distant metastasis
  • Contralateral (opposite) lung disease was noted in 55 patients (35%) and multiple parenchymal lung metastases in 42 (26%)
  • Peritoneal and/or omental involvement was noted in 36 patients (22%), with ascites in 24
  • Bone metastases were diagnosed in 31 patients (19%); the majority of bone lesions (18, 60%) were described as lytic
  • Visceral metastases (liver, kidney, adrenal, spleen) were found in 23 patients (14% of total), most in the liver (19 of 27 sites, 70%)
  • Five patients (3%) had brain metastases confirmed radiologically; all had neurological symptoms that prompted imaging
  • Subcutaneous metastatic nodules away from the tumour and from any chest drain or biopsy site were noted in 32 patients (20%)
  • Peritoneal metastases occurred in 27.0% of epithelioid cases compared with 4.3% of biphasic/sarcomatoid cases (p = 0.015)
  • Bone metastases occurred in 18.2% of epithelioid and 34.7% of biphasic/sarcomatoid cases; the difference did not reach statistical significance (p = 0.0936)
  • Median overall survival for the whole group was 23.8 months (range 1 to 106 months) from diagnosis; the date of death was known for 122 patients (74%)
  • Epithelioid subtype had statistically significantly better overall survival than biphasic and sarcomatoid subtypes (p = 0.004)
  • Presence or absence of metastatic disease or locally invasive disease did not correlate with overall survival
  • Among those with metastatic disease, survival with versus without peritoneal/omental-only metastases was 23.9 vs 22.0 months (HR 0.64, p = 0.54)
  • Survival with versus without visceral-only metastasis was 18.9 vs 25.7 months (HR 2.36, p = 0.07), not statistically significant
• The authors' conclusion: The authors concluded that, with 67% of patients having distant metastases, advanced malignant pleural mesothelioma should no longer be considered a local disease without the propensity to spread. Given an almost 20% bone metastasis rate, they wrote that routine or symptom-driven bone imaging should be considered. They saw no correlation between the presence of metastatic disease and survival.
• Limitations the authors state:
  • The analysis was retrospective, and some metastatic sites may not have been identified on the imaging used
  • Brain imaging was done only when neurological symptoms were present, so brain metastases without symptoms may have been missed
  • Imaging methods changed over the study period (more plain X-rays earlier, more CT later), and advances in imaging may have found sites missed a decade earlier
  • Usually only one set of images came from the referring hospital, so the timing of when metastases developed could not be assessed

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, Pleura, Epithelioid, Biphasic Mesothelioma, Sarcomatoid, Overall Survival, Prognosis.

Related studies

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• Distant Metastatic Pattern and Its Prognostic Significance in Malignant Pleural Mesothelioma: A Population-Based Study Based on a Machine Learning Model — J. Yu, C. Peng, et al. (2025)
• Synthesis and biological evaluation of O-[3-18F-fluoropropyl]-α-methyl tyrosine in mesothelioma-bearing rodents — I.H. Shih, F.L. Kong, et al. (2013)
• Evaluation of imaging techniques for early detection of intrathoracic cancers in symptomatic patients in primary care: a systematic review — B. Grigore, J.L. Peters, et al. (2025)
• Diffuse pleural mesothelioma with distant bone metastasis. A case report — R.N. Laurini (1974)
• Distant visceral metastases in pleural mesothelioma — G.H. Roberts (1976)

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