The role of radiation treatment in pleural mesothelioma: Highlights of the 14th International Conference of the International mesothelioma interest group

Our plain-English summary of The role of radiation treatment in pleural mesothelioma: Highlights of the 14th International Conference of the International mesothelioma interest group, by R.M. MacRae, M. Ashton, O. Lauk, et al (Lung Cancer, 2019).

The study

• Authors: R.M. MacRae, M. Ashton, O. Lauk, W. Wilson, N. O'Rourke, C.B. Simone, A. Rimner
• Journal: Lung Cancer
• Published: 2019;132:24-27
• Type of article: Review
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Radiation remains an important component of mesothelioma treatment in 2018. Its use as a treatment modality continues to evolve as the technology for planning and delivery continues to improve. Use of radiation to improve local control in the involved hemithorax has been a common adjuvant treatment post extrapleural pneumonectomy for many years. Modern treatment options with advanced planning techniques including protons and intensity modulated radiation therapy lead to new potential options for treatment post lung-sparing surgery or in the unresectable setting. Presentations and discussions on the implementation of these strategies for palliation, treatment of oligometastatic recurrence or unresectable disease were the focus of a session dedicated to the role of radiation therapy at the 14th International Conference of the International Mesothelioma Interest Group and are reviewed in this article. Preclinical data to better understand how to integrate radiation and the delivery of novel systemic therapy approached like check point inhibitors are also presented.

Copyright © 2019 Elsevier B.V. All rights reserved.

In plain English

This article was a review summarizing a session on radiation treatment for malignant pleural mesothelioma at the International Mesothelioma Interest Group conference in Ottawa, Canada, in May 2018. One presentation described SYSTEMS-2, a UK randomised trial of pain relief comparing a higher dose (36 Gy in 6 fractions) with the standard 20 Gy in 5 fractions. It planned 112 patients and had 37 randomised so far. A Zürich group reported 12 patients whose mesothelioma recurred at a few sites after surgery, treated mostly with stereotactic body radiotherapy (SBRT) to 29 lesions. Control of treated lesions was 94% at 12 months. One patient died of massive esophageal bleeding three months after radiotherapy. Australian researchers reported mouse experiments with asbestos-derived mesothelioma cell lines. In these, adding a single checkpoint-blocking drug to radiotherapy did not appear to improve outcomes for the second, unirradiated tumours under the schedule used, though local tumour control increased. The authors concluded that the session showed radiotherapy to be a highly effective treatment for this disease. They noted that many of these strategies are still at an early stage.

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 (summary of presentations and discussion at a conference session on radiotherapy)
• Who was studied: Presentations at the radiotherapy session of the 14th International Mesothelioma Interest Group conference in Ottawa, Canada, May 2018. These covered a UK randomised trial in progress, a Zürich retrospective series of 12 patients treated from 2005 to 2015, and Australian mouse experiments.
• Exposure: Radiation treatment for malignant pleural mesothelioma: palliative radiotherapy for pain, SBRT for recurrent disease, and radiotherapy with checkpoint inhibitors in mice. The mouse tumours came from asbestos-derived murine mesothelioma models (AB1 and AE17 cell lines).
• Main results:
  • SYSTEMS-2, a UK randomised phase II trial, compares a dose-escalated regimen (36 Gy in 6 fractions) with the standard dose (20 Gy in 5 fractions) for pain control. It plans to recruit 112 patients from 10 to 20 UK centres.
  • SYSTEMS-2 status at the time of the review: 44 patients registered, 37 randomised; no outcome results reported.
  • Zürich retrospective series: 12 patients with recurrent disease after macroscopic complete resection received salvage SBRT to a total of 29 lesions.
  • In the Zürich series, crude in-field failure was 7%, and control of treated metastases was 94% at 12 months.
  • In the Zürich series, median progression-free survival after SBRT was 11 months (95% CI 5.6 to 26.4). Overall survival at 3 years was 71.3%, and median overall survival had not been reached.
  • In the Zürich series, two patients had serious toxicity. One had a fractured rib near the radiation field. The other had an upper GI hemorrhage and died of massive esophageal bleeding three months after radiotherapy.
  • In mice with AB1 tumours, radiotherapy with 18 or 27 Gy reduced tumour growth compared with non-irradiated control tumours, while 9 Gy showed no significant effect.
  • In the mouse experiments, adding single-agent checkpoint blockade to radiotherapy did not affect the secondary (non-irradiated) tumours synergistically. The authors wrote that it does not appear capable of improving secondary tumour outcomes with the scheduling used.
  • In the same mouse experiments, increased local tumour control was observed.
• The authors' conclusion: The authors concluded that the session demonstrated radiotherapy to be a highly effective treatment in malignant pleural mesothelioma, even for patients who cannot have radical surgery and hemithorax radiation.
• Limitations the authors state:
  • The authors stated that many of the strategies discussed are still at an early level of implementation.

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, Hemithorax, Extrapleural Pneumonectomy (EPP), Unresectable, Systemic Therapy.

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• Molecular pathways and diagnosis in malignant mesothelioma: A review of the 14th International Conference of the International Mesothelioma Interest Group — D.B. Chapel, A. Churg, et al. (2019)
• 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)
• Progress of malignant mesothelioma research in basic science: A review of the 14th international conference of the international mesothelioma interest group (iMig2018) — L. Wu, I. Dell'Anno, et al. (2019)
• 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)
• The Use of Radiation Therapy for the Treatment of Malignant Pleural Mesothelioma: Expert Opinion from the National Cancer Institute Thoracic Malignancy Steering Committee, International Association for the Study of Lung Cancer, and Mesothelioma Applied Research Foundation — D.R. Gomez, A. Rimner, et al. (2019)

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