Trimodality therapy of malignant pleural mesothelioma with helical tomotherapy

Our plain-English summary of Trimodality therapy of malignant pleural mesothelioma with helical tomotherapy, by H. Ozyurt, S. Ozdemir, B. Dogan, et al (Northern Clinics of Istanbul, 2023).

The study

• Authors: H. Ozyurt, S. Ozdemir, B. Dogan, G. Gunalp, A.S. Ozden
• Journal: Northern Clinics of Istanbul
• Published: 2023;10(2):172-180
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: The purpose of this study was to determine the efficacy and tolerability of hemithoracic radiotherapy implemented with helical tomotherapy (HTT) in malignant pleural mesothelioma (MPM) patients.

Methods: Between October 2018 and December 2020, data from 11 MPM patients who received trimodality therapy, including lung-sparing surgery (pleurectomy-decortication, P/D), adjuvant chemotherapy (cisplatin+ pemetrexed), and radiotherapy, were retrospectively reviewed. HTT was used to deliver a total of 30 Gy, 50-54 Gy or 59.4-60 Gy to R2 disease with 1.8-2 Gy daily doses. Descriptive data are presented in number (percentage) or median (minimum- maximum). The Kaplan-Meier method was used to calculate survival data. In patients with toxicities, the risk organ doses were compared using the Mann-Whitney U test.

Results: The median follow-up was 20.5 (12-30) months. Two-year local control, disease-free, and overall survival rates were 48.5%, 49%, and 77.9%, respectively. The median prescribed dose for planning target volume (PTV) was 50.4±8.7 (30-60) Gy. Mean dose (Dmean) of total lung was 19.9±6 (10.4-26) Gy; the V20 (%) of ipsilateral and contralateral lungs were 89.±11.2 (62.7-100) and 0.7±2.1 (0.49-5.9), respectively. Esophageal Dmean and maximum doses (Dmax) were found as 21.7±8.4 (7.4-34) and 53.1±10.4 (25.4-64.4) Gy, respectively. V30 (%) and Dmean of heart were 22.3%±13.4% (3.9-47) and 21±5.7 (10.8-29.3) Gy, respectively. Dmax of medulla spinalis (MS) was 38.6± 1.3 (13.7-48) Gy. Grade 1-2 radiation pneumonitis (RP) developed in 4 (36.4%) and esophagitis in 2 (18.2%) patients. RP was found to be associated with MS and esophageal doses (p<0.05). Myelitis was diagnosed in 1 (9.1%) patient (MS Dmax: 29 Gy).

Conclusion: HTT can be used as part of trimodality therapy for MPM patients with acceptable toxicities. MS and esophageal doses should be considered for radiation pneumonitis risk, and new dose constraints for these organs should be defined.

© Copyright 2023 by Istanbul Provincial Directorate of Health.

In plain English

This retrospective review covered 11 patients with malignant pleural mesothelioma treated at an Istanbul hospital from October 2018 to December 2020. Each had lung-sparing surgery (pleurectomy/decortication), then cisplatin and pemetrexed chemotherapy, then radiotherapy to the affected side of the chest by helical tomotherapy. The article did not report the patients' asbestos exposure. One patient received 30 Gy because of the COVID-19 pandemic; the others received at least 45 Gy. Two-year local control, disease-free and overall survival rates were 48.5%, 49% and 77.9%. No patient had grade 3 or higher side effects. Radiation pneumonitis (lung inflammation) developed in 4 patients (36.4%) and esophagitis in 2 (18.2%). Patients with pneumonitis had significantly higher spinal cord doses and higher maximum esophageal doses. The share of their heart receiving at least 20 Gy was higher, but not significantly. One patient was diagnosed with transverse myelitis; the authors said radiation myelitis could not be excluded. The authors concluded the treatment can be used with acceptable toxicities and that spinal cord and esophageal doses should be kept as low as possible, with new dose limits possibly needed. They noted the study was retrospective and small.

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 patient records (case series) from one hospital
• Who was studied: 11 patients diagnosed with malignant pleural mesothelioma (MPM) and treated with trimodality therapy, October 2018 to December 2020, at Kartal Dr. Lutfi Kirdar City Hospital, Istanbul, Turkiye. There were 8 men and 3 women, median age 57 (range 22 to 70). Tumor types were 72.7% epithelioid, 18.2% biphasic and 9.1% sarcomatoid.
• Exposure: The article gives no asbestos exposure data for the patients. What it studied was treatment: lung-sparing surgery, cisplatin plus pemetrexed chemotherapy, and hemithoracic radiotherapy by helical tomotherapy. One patient received 30 Gy in 10 fractions. All others received at least 45 Gy in daily doses of 1.8 to 2 Gy, for totals of 50 to 60 Gy.
• Main results:
  • Two-year local control was 48.5%, disease-free survival 49% and overall survival 77.9% in the 11 patients.
  • Median follow-up was 20.5 months (range 12 to 30).
  • No patient had grade 3 or higher toxicity. Radiation pneumonitis developed in 4 of 11 patients (36.4%) within 6 months after radiotherapy.
  • Esophagitis developed in 2 patients (18.2%) during radiotherapy.
  • Patients with radiation pneumonitis had significantly higher spinal cord (medulla spinalis) doses than those without, with p less than 0.05. Maximum dose was 45.5 vs 35.8 Gy and mean dose 19.2 vs 10.7.
  • Maximum esophageal dose was significantly associated with radiation pneumonitis (61 vs 51.6, p=0.01).
  • Patients with radiation pneumonitis had a higher heart V20, the percentage of heart volume receiving at least 20 Gy (55.3 vs 26.6). The difference was not statistically significant (p=0.067).
  • In the discussion, the authors reported that one patient was diagnosed with transverse myelitis. They said radiation myelitis could not be excluded in that patient. The results section calls this case radiation myelitis.
  • In that patient, the maximum and mean spinal cord doses were reported as 29.1 and 19 Gy.
  • The authors recommended keeping spinal cord and esophageal doses as low as possible. They said new dose constraints, particularly for the spinal cord, may be required.
• The authors' conclusion: The authors concluded that helical tomotherapy can be used as part of trimodality therapy for MPM patients with acceptable toxicities.
• Limitations the authors state:
  • The study was retrospective, and the small number of patients prevented subgroup analyses linking radiation dose measures to survival.

Topics

Medical terms in this study, explained in our Lexicon: Trimodality Therapy, Pleural Mesothelioma, Pleurectomy/Decortication (P/D), Chemotherapy, Cisplatin, Pemetrexed (Alimta), Overall Survival, Pneumonitis.

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• Dosimetric evaluation of helical tomotherapy and volumetric-modulated arc therapy for malignant pleural mesothelioma: a planning study for dose escalation — F.L. Zhang, N. Lu, et al. (2021)
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• Mesothelioma at era of helical tomotherapy: results of two institutions in combining chemotherapy, surgery and radiotherapy — A. Sylvestre, M.A. Mahé, et al. (2011)
• Hemithoracic intensity-modulated radiotherapy using helical tomotherapy for patients after extrapleural pneumonectomy for malignant pleural mesothelioma — T. Ebara, H. Kawamura, et al. (2012)

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