Current readings: improvements in intensity-modulated radiation therapy for malignant pleural mesothelioma

Our plain-English summary of Current readings: improvements in intensity-modulated radiation therapy for malignant pleural mesothelioma, by K.E. Rosenzweig (Seminars in Thoracic and Cardiovascular Surgery, 2013).

The study

• Author: K.E. Rosenzweig
• Journal: Seminars in Thoracic and Cardiovascular Surgery
• Published: 2013;25(3):245-50
• Type of article: Review
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The treatment of malignant pleural mesothelioma with radiation therapy has always been a technical challenge. Early experience with intensity-modulated radiation therapy demonstrated troubling toxicity. Recent reports from institutions have demonstrated that with greater experience, intensity-modulated radiation therapy can be delivered safely, both in the setting of pneumonectomy or pleurectomy. After pneumonectomy, the dose to the contralateral lung must be minimized, preferably with a volume of lung receiving 20 Gy (V20) to less than 5% and a mean lung dose of approximately 10%. In the setting of 2 intact lungs, the mean lung dose can be as high as 20 Gy. Expected rates of grade 3 or worse radiation pneumonitis are 12%-20%. The rates of fatal pneumonitis are approximately 3%-8% in these studies, which demonstrate the considerable toxicity of treatment, even with improved technique.

© 2013 Published by Elsevier Inc.

In plain English

This article is a review, not a new study. The author summarized five published reports on intensity-modulated radiation therapy (IMRT), a precisely shaped radiation technique, for malignant pleural mesothelioma. Three reports covered patients treated after extrapleural pneumonectomy, surgery that removes the lung and its lining. Two covered patients after pleurectomy/decortication or biopsy alone, where the lung stays in place. Across the three post-pneumonectomy studies (24, 30 and 86 patients), the author put the rate of grade 3 or worse radiation pneumonitis, a lung inflammation, at 12%-16% and fatal toxicity at 3%-8%. An earlier Dana-Farber report, not among the five, had found a 46% risk of fatal toxicity from radiation pneumonitis. In one intact-lung study, 2 of 28 patients (7%) had grade 3 respiratory toxicity and none had fatal (grade 5) respiratory toxicity. In the other, 7 of 36 patients (20%) had grade 3 or worse toxicity, including one fatality. The author concluded that the ability to deliver IMRT had improved with experience, but that toxicity, though decreased, was not insignificant. The article did not examine asbestos exposure.

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 ('Current Readings') of five recently published studies on IMRT for malignant pleural mesothelioma
• Who was studied: Patients with malignant pleural mesothelioma in five published studies. Three studies covered treatment after extrapleural pneumonectomy: 24 patients (Curie Institute and Rene Gauducheau Cancer Center, France), 30 patients (University of North Carolina) and 86 patients (M.D. Anderson Cancer Center). Two studies covered treatment after pleurectomy/decortication or biopsy alone: 28 patients (Aviano, Italy) and 36 patients (Memorial Sloan-Kettering Cancer Center).
• Exposure: No asbestos exposure was studied. The exposure examined was radiation treatment: IMRT, including helical tomotherapy, given after extrapleural pneumonectomy or after pleurectomy/decortication or biopsy.
• Main results:
  • M.D. Anderson study (86 patients after extrapleural pneumonectomy): grade 3 or worse pulmonary toxicity occurred in 11.6% of patients. There were 5 fatal cases of pulmonary toxicity: 3 from radiation pneumonitis and 2 from bronchopleural fistula.
  • M.D. Anderson study: at 2 years, overall survival was 32%, local control 55% and distant control 40%.
  • University of North Carolina study (30 patients after extrapleural pneumonectomy): 4 patients (13%) developed radiation pneumonitis, including one fatality (3%).
  • University of North Carolina study: when the first 15 patients were compared with the second 15, the mean dose to the heart and lung improved in the second group, as did target coverage.
  • French helical tomotherapy study (24 patients after extrapleural pneumonectomy): 4 (16%) had grade 3 or worse radiation pneumonitis within 6 months, including 2 deaths (8%).
  • Aviano, Italy study (28 patients after pleurectomy/decortication or biopsy): 5 patients (18%) had respiratory toxicity, 2 of them grade 3 (7%), and none had grade 5 (fatal) respiratory toxicity.
  • Memorial Sloan-Kettering study (36 patients after pleurectomy/decortication or biopsy alone): 7 patients (20%) had grade 3 or worse toxicity, including one fatality.
  • Across the three post-pneumonectomy studies, the author reported pneumonitis rates of 12%-16% and fatal toxicity rates of 3%-8%. The article's Table 1 lists these figures as grade 3 or worse radiation pneumonitis and fatal (grade 5) radiation pneumonitis.
  • The author compared this with the earlier Dana-Farber report, which found a 46% risk of fatal toxicity from radiation pneumonitis after IMRT following extrapleural pneumonectomy. The author attributed the difference mainly to more restrictive dose limits. The volume of lung receiving 20 Gy (V20) was 20% in the Dana-Farber report, and most centers now try to keep it below 5%.
  • The author noted that toxicity had decreased but was not insignificant.
• The authors' conclusion: The author concluded that all five studies showed the ability to deliver IMRT for mesothelioma had improved with experience.
• Limitations the authors state:
  • The author noted that the reviewed studies came from centers treating high volumes of patients, where such expertise could be developed.
  • In comparing the reviewed studies with the earlier Dana-Farber report, the author stated it is unknown whether the heated intrapleural chemotherapy given to 85% of Dana-Farber patients added to IMRT toxicity.

Topics

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

Medical terms in this study, explained in our Lexicon: Intensity-Modulated Radiation Therapy (IMRT), Pleural Mesothelioma, Pneumonectomy, Pneumonitis.

Related studies

• Geometric dose prediction model for hemithoracic intensity-modulated radiation therapy in mesothelioma patients with two intact lungs — L. Kuo, E.D. Yorke, et al. (2016)
• Intensity-modulated radiation therapy with simultaneous integrated boost in unresected left-sided pleural mesothelioma: a case report — S. Cilla, C. Digesú, et al. (2010)
• Intensity-Modulated Radiation Therapy Improves the Target Coverage Over 3-D Planning While Meeting Lung Tolerance Doses for All Patients With Malignant Pleural Mesothelioma — S. Ulger, E. Cetin, et al. (2017)
• Patterns of failure, toxicity, and survival after extrapleural pneumonectomy and hemithoracic intensity-modulated radiation therapy for malignant pleural mesothelioma — D.R. Gomez, D.S. Hong, et al. (2013)
• Intensity modulated radiation therapy after extra-pleural pneumonectomy for malignant pleural mesothelioma is feasible without fatal pulmonary toxicity and provides good survival — S. Jhavar, J. Pruszynski, et al. (2018)
• Adjuvant intensity-modulated proton therapy in malignant pleural mesothelioma. A comparison with intensity-modulated radiotherapy and a spot size variation assessment — S. Lorentini, M. Amichetti, et al. (2012)

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