Intensity-modulated radiotherapy is a safe and effective treatment for localized malignant pleural mesothelioma

Our plain-English summary of Intensity-modulated radiotherapy is a safe and effective treatment for localized malignant pleural mesothelioma, by M. Simon, T. Shochat, N. Peled, et al (Thoracic Cancer, 2018).

The study

• Authors: M. Simon, T. Shochat, N. Peled, A. Zer, M.R. Kramer, O. Eldan, M. Saute, E.R. Dudnik, A.M. Allen
• Journal: Thoracic Cancer
• Published: 2018;9(11):1470-1475
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant pleural mesothelioma (MPM) is a rare disease and management of localized disease is controversial. Radiotherapy has been shown to be useful after extrapleural pneumonectomy (EPP), as well as with less aggressive surgery. As no reports of the treatment of this disease have ever been published from Israel, we report our experience with MPM and intensity-modulated radiotherapy (IMRT).

Methods: The complete medical records of patients treated for MPM at the Rabin Medical Center from 1 August 2007 to 31 March 2016 were reviewed. Twenty-seven patients were treated with IMRT, either post-EPP or without EPP. Patients received 54 Gy in 2 Gy fractions using the restricted field IMRT technique. Chemotherapy was administered sequentially in 26% of patients. Patients were followed up from the date of diagnosis to death or treatment failure.

Results: Seventy-eight percent of patients had the epithelioid subtype. Nearly all patients were male (85%) and 90% of non-surgical patients were administered chemotherapy compared to 56% of post-EPP patients. All patients completed therapy and only 16% had grade 1-2 radiation pneumonitis, with no incidence of grade 3 or higher. The median follow-up was 22 months and the mean overall survival was 34.9 months. The mean time to progression following radiation therapy was 26.7 months. The mean time to local and distant failure was 19 and 16 months, respectively.

Conclusions: IMRT for localized pleural mesothelioma is a tolerable and effective therapy both post-EPP or without surgery. These results suggest that future investigation in this area is required.

© 2018 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.

In plain English

This was a retrospective review of 27 patients with malignant pleural mesothelioma treated with intensity-modulated radiotherapy (IMRT), a targeted form of radiation, at Rabin Medical Center in Israel between August 2007 and March 2016. Sixteen patients had first had extrapleural pneumonectomy (surgery removing the lung and its lining). The other 11 were treated without that surgery. Nine of the 27 had been exposed to asbestos, but the study did not examine asbestos further. All patients completed radiotherapy without breaks. Grade 1–2 radiation pneumonitis (lung inflammation) occurred in 16%, and no patient had grade 3 or higher. Local progression in the chest occurred in 3 of 16 patients who had extrapleural pneumonectomy and 5 of 11 who did not. Spread to distant sites occurred in 13 patients (48%). Median follow-up was 22 months, and mean overall survival was 34.9 months. Left-sided tumors were linked to better survival. The authors concluded that IMRT was feasible and effective. They noted that the study was small and retrospective, and that it used extrapleural pneumonectomy rather than lung-sparing surgery. Several figures differ between the article's abstract, table and text.

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 medical records from a single hospital (case series); no comparison group
• Who was studied: 27 patients with malignant pleural mesothelioma (MPM) who had complete medical records and were treated with radiotherapy at Davidoff Cancer Center, Rabin Medical Center, Israel, between 1 August 2007 and 31 March 2016. 16 had radiotherapy after extrapleural pneumonectomy (EPP) and 11 had lung-sparing treatment; one of the 11 had pleurectomy/decortication.
• Exposure: The study examined a treatment, not asbestos exposure: IMRT to 54 Gy to the entire hemithorax (one side of the chest), given after EPP or without surgery, with sequential cisplatin-pemetrexed chemotherapy in some patients. Asbestos exposure was recorded only as a patient characteristic (9 of 27), with no fiber types or sources given.
• Main results:
  • 9 of the 27 patients (33%) had been exposed to asbestos.
  • All patients completed the prescribed radiotherapy without treatment breaks.
  • Acute side effects across all patients: grade 1 weight loss in 23%, grade 1 fatigue in 30%, and grade 1–2 radiation pneumonitis in 16%.
  • No patient had grade 3 or higher radiation pneumonitis.
  • Local progression in the chest occurred in 8 of 27 patients (30%): 3 in the post-EPP group (19%) and 5 in the non-EPP group (45%).
  • Distant failure (spread beyond the chest) occurred in 13 patients (48%).
  • For all patients, the median follow-up was 22 months, mean overall survival was 34.9 months, and mean time to progression after radiotherapy was 26.7 months.
  • Mean time to local failure was 19 months, and mean time to distant failure was 16 months.
  • In univariate analysis, tumor location was the only factor significantly linked to overall survival, favoring left-sided disease (hazard ratio 0.211, confidence interval 0.063 to 0.705; P = 0.011).
  • Biphasic histology, found in only 2 patients, was associated with an almost seven-fold likelihood of progression after radiotherapy (hazard ratio 6.930, confidence interval 1.34 to 35.72; P = 0.02).
  • In the non-operable patients, median time to progression was 12 months and median overall survival was 13.5 months (range 8 to 49).
• The authors' conclusion: The authors concluded that modern IMRT was feasible and effective. They also concluded that its low toxicity and encouraging local control and survival suggest radiotherapy is a treatment option for localized MPM. They called for larger and prospective studies.
• Limitations the authors state:
  • The study was retrospective; the authors say prospective analysis is needed.
  • The series was small, and patients had EPP rather than pleurectomy/decortication (lung-sparing surgery).

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: Intensity-Modulated Radiation Therapy (IMRT), Pleural Mesothelioma, Extrapleural Pneumonectomy (EPP), Chemotherapy, Epithelioid, Pneumonitis, Overall Survival.

Related studies

• Intensity-modulated radiotherapy after extrapleural pneumonectomy in the combined-modality treatment of malignant pleural mesothelioma — A. Chi, Z. Liao, et al. (2011)
• Intensity-modulated radiotherapy for relapsed malignant pleural mesothelioma — C. Spatola, C. Militello, et al. (2016)
• Single-institution experience of intensity-modulated radiotherapy for malignant pleural mesothelioma at University of Catania — C. Spatola, C. Militello, et al. (2018)
• Extra-pleural pneumonectomy in the era of image-guided intensity-modulated radiotherapy — M. Trovo, D. Franceschini, et al. (2019)
• 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)
• Optimal gross tumor volume definition in lung-sparing intensity modulated radiotherapy for pleural mesothelioma: an in silico study — A. Botticella, G. Defraene, et al. (2016)

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