Stereotactic Body Radiation Therapy (SBRT) as Salvage Therapy for Oligorecurrent Pleural Mesothelioma After Multi-Modality Therapy

Our plain-English summary of Stereotactic Body Radiation Therapy (SBRT) as Salvage Therapy for Oligorecurrent Pleural Mesothelioma After Multi-Modality Therapy, by C. Schröder, I. Opitz, M. Guckenberger, et al (Frontiers in Oncology, 2019).

The study

• Authors: C. Schröder, I. Opitz, M. Guckenberger, R. Stahel, W. Weder, R. Förster, N. Andratschke, O. Lauk
• Journal: Frontiers in Oncology
• Published: 2019;9:961
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Therapy options for patients with oligoprogressive malignant pleural mesothelioma (MPM) are limited. Stereotactic Body Radiotherapy (SBRT) may be a promising therapeutic option, as it delivers a localized ablative dose of radiation and therefore balances efficacy and treatment related toxicities. The intent of this retrospective analysis was to evaluate the feasibility of SBRT for limited pleural recurrences. Methods and Materials: This retrospective single-institution study is based on the 21 consecutive patients treated with hypofractionated radiotherapy for oligoprogressive MPM. Clinical and radiological data was collected at regular follow-up visits including toxicity, local control and survival. Results: At primary diagnosis, 57% of the patients presented with stage III disease. Initial treatment of MPM consisted of induction chemotherapy (n = 12) prior to a macroscopic complete resection (n = 18). Three patients received additional intracavitary chemotherapy and another three patients were treated with chemotherapy alone without another treatment at the time of first diagnosis. A total of 50 lesions in recurrent MPM were treated with SBRT. The median number of radiotherapy fractions was 5 (range 3-20) with a median dose per fraction of 5 Gy (range 2.5-12.5 Gy). The median total treatment dose was 30 Gy (20-50 Gy) with a median prescription isodose line (IDL) of 65% (65-100%). Median follow-up of all patients from diagnosis was 28 months (range 7-152 months). Analyzing all lesions separately, the 12-months-local control from SBRT was 73.5%. The median progression free survival (PFS) after SBRT was 6 months (range 0-21 months) and the median OS from first first SBRT was 29 months (range 0-61 months). Only one patients experienced above Grade 3 toxicities. Conclusion: This analysis demonstrates the feasibility of a SBRT approach for oligorecurrent MPM. SBRT was well-tolerated even after multiple repetitions and local control was high with a promising median OS.

Copyright © 2019 Schröder, Opitz, Guckenberger, Stahel, Weder, Förster, Andratschke and Lauk.

In plain English

This retrospective study at University Hospital Zurich looked at 21 patients with malignant pleural mesothelioma (MPM) that had come back in a limited way (at most three lesions) after earlier treatment. Most had earlier had surgery, often after chemotherapy. From 2010 to 2018 they received stereotactic body radiation therapy (SBRT), a precisely targeted radiotherapy. Ten had a second course and four a third; 50 lesions were treated. The article does not report asbestos exposure. At 12 months, 73.5% of treated lesions were controlled. After the first course, cancer returned in the chest in 13 of 21 patients. Median progression-free survival after first SBRT was 6 months; median overall survival was 29 months. One patient had grade 3 or worse side effects: upper digestive-tract bleeding during treatment of tumor invading the esophagus. That patient died 3 months later of massive esophageal bleeding and progressive disease. The authors interpreted this as the radiation combined with the infiltrating, progressive disease. The authors concluded that SBRT appeared feasible and safe. As a limitation, they noted that the patients had different earlier treatments and different timing of radiotherapy.

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 single-institution study (the authors also call it a case series)
• Who was studied: 21 patients with malignant pleural mesothelioma, treated between 2010 and 2018 at the authors' institution (University Hospital Zurich, Switzerland). They received radiotherapy for limited recurrence in the chest. There were 17 males and 4 females; 17 had epithelioid, 2 sarcomatoid and 2 biphasic tumors. Median age at first diagnosis was 65 years (range 33 to 75), and 57% had IMIG stage III disease at first diagnosis. Of the 21, 18 had had macroscopic complete resection (12 of them after platinum-based induction therapy), and 3 had had chemotherapy alone.
• Exposure: The study examined a treatment, not asbestos exposure, which the article does not report. The treatment was stereotactic body radiation therapy to recurrent lesions, given as a median of 5 fractions (range 3 to 20). The median dose was 5 Gy per fraction (range 2.5 to 12.5 Gy) and the median total prescription dose was 30 Gy (range 20 to 50 Gy). Up to 25% of patients were also treated with a palliative pain-relief approach. Two patients received concurrent pembrolizumab.
• Main results:
  • All 21 patients received one course of radiation, 10 received a second and 4 a third. In total, 50 lesions were treated.
  • Analyzing all lesions separately, 12-month local control of the irradiated lesions was 73.5%.
  • After the first SBRT course, 13 of 21 patients had a recurrence in the chest: 11 outside the treated field and 2 inside it.
  • After the second and third courses, recurrence in the chest occurred in 6 of 10 and 2 of 4 patients respectively. In each case, half of the recurrences were inside the treated field.
  • Across all 21 patients, median progression-free survival after first SBRT was 6 months (range 0 to 21 months). Median overall survival after first SBRT was 29 months (range 0 to 61 months).
  • Overall survival at 3 years was 9.5%.
  • At the time of analysis, 11 of the 21 patients were still alive. Median follow-up from diagnosis was 28 months (range 7 to 152 months).
  • One patient had grade 3 or higher toxicity. This patient's MPM was infiltrating the esophagus, and the patient was hospitalized during treatment for upper gastrointestinal bleeding. The patient died 3 months later of massive esophageal bleeding and progressive disease. The authors interpreted this as a combination of the radiation and the infiltrating, progressive disease.
• The authors' conclusion: The authors concluded that SBRT appears feasible and safe for oligoprogressive MPM, especially for patients in reduced general condition after multiple earlier therapies. They proposed it may be a promising approach to delay systemic therapy in selected patients, and they called for further studies.
• Limitations the authors state:
  • The patient group was not uniform: patients had different earlier therapies and received radiotherapy at different time points.
  • Because the disease infiltrates tissue, lesions might be missed or underestimated even with PET-CT planning, so not all lesions may have received a sufficient dose.
  • The radiation doses used were lower than the ablative doses used in phase I or II trials of oligometastatic lesions from other cancers.

Topics

Medical terms in this study, explained in our Lexicon: Stereotactic Body Radiation Therapy (SBRT), Pleural Mesothelioma, Chemotherapy.

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