Use of Continuous Positive Airway Pressure (CPAP) to Limit Diaphragm Motion-A Novel Approach for Definitive Radiation Therapy for Inoperable Pleural Mesothelioma: A Pilot Study

Our plain-English summary of Use of Continuous Positive Airway Pressure (CPAP) to Limit Diaphragm Motion-A Novel Approach for Definitive Radiation Therapy for Inoperable Pleural Mesothelioma: A Pilot Study, by A. Moore, M.J. Kindler, A.M. Allen (Biology, 2021).

The study

• Authors: A. Moore, M.J. Kindler, A.M. Allen
• Journal: Biology
• Published: 2021;10(8)
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is a deadly disease and radiotherapy (RT) plays an important role in its management. Recent developments in technique have made it is possible to deliver RT to MPM in the intact lung. However, it is imperative to reduce normal lung doses. We present a pilot study examining the use of CPAP and VMAT radiotherapy to reduce toxicity when treating MPM, involving three consecutive patients with MPM, not amenable to surgery, who were treated according to Helsinki committee approval. Patients were simulated using four-dimentional CT simulation with the assistance of CPAP lung inflation, then were treated using both IMRT and VMAT techniques. Radiation lung dose was optimized based on accepted lung dose constraints. Patients were followed for toxicity as well as local control and survival. Results: Three patients were treated with CPAP-based IMRT treatment. These patients tolerated the treatment and DVH constraints were able to be met. The comparison plans among the four VMAT arcs and the IMRT static field treatment were able to accomplish the treatment planning objectives without significant advantages with either technique. The treatment combined with CPAP reduced the normal lung dose in MPM patients with intact lungs. This technique is worthy of further investigation.

In plain English

This pilot report from Rabin Medical Center's Davidoff Cancer Center in Israel described three consecutive patients with biopsy-proven malignant pleural mesothelioma who were treated without surgery. They received radiotherapy while wearing a CPAP mask, which inflates the lungs. One man had worked in asbestos production. Of the other two, the article reported no asbestos exposure for one and no history of asbestos exposure for the other. The table lists 54 Gy for each patient; the text gives 60 Gy for one. Treatment used IMRT, and each plan was redone with VMAT for comparison only. A 75-year-old woman developed persistent grade 3 pneumonitis, later had liver metastases, and died in November 2018. One man had no adverse events and a partial response. Both men's disease later progressed; both were alive when the article was written. The authors reported that dose limits were met and neither planning technique was significantly better, though their tables show both-lung V5 of 64.7% and 62.57% against a limit under 60%. They concluded that CPAP may improve dosimetry and reduce toxicity and should be further explored.

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: Pilot case series of three patients treated with CPAP-assisted radiotherapy, with a planning sub-study that re-planned the IMRT treatments with VMAT for comparison
• Who was studied: Three consecutive patients with biopsy-proven malignant pleural mesothelioma, enrolled in a CPAP study at the Davidoff Cancer Center, Rabin Medical Center, Israel. None was treated surgically: Patient 1 was judged inoperable, Patient 2 refused surgery, and Patient 3 was referred for radiotherapy after a drug trial. They were diagnosed in 2017 and treated between August 2017 and February 2018. The patients were a 75-year-old woman and two men aged 62 and 65.
• Exposure: The exposure studied was radiotherapy (IMRT, re-planned with 4-arc VMAT) given with CPAP lung inflation. CPAP pressure started at 4 mmHg and was raised toward a goal of 15 mmHg. Asbestos history: Patient 2 worked in asbestos production. Patient 1 is described as having no asbestos exposure, and Patient 3 as having no history of asbestos exposure. No fiber type was named.
• Main results:
  • Patient 1 (75-year-old woman, biphasic MPM, described as having no asbestos exposure) developed persistent grade 3 pneumonitis after radiotherapy. During treatment this patient had grade 3 thrombocytopenia due to suspected immune thrombocytopenia. Liver metastases were found later, and the patient died in November 2018.
  • Patient 2 (62-year-old man who worked in asbestos production, epithelioid MPM) refused surgery. He had no adverse events from 54 Gy and a partial response on PET/CT in December 2017. His disease progressed in August 2018, and he was alive at the time of writing.
  • Patient 3 (65-year-old man, no history of asbestos exposure, epithelioid MPM) was treated to 54 Gy. There was no progression until July 2018, when distant nodal involvement and peritoneal spread appeared. The thoracic disease remained stable until late September 2018.
  • Both-lung mean lung dose was 17.051, 11.3 and 17.06 for Patients 1, 2 and 3. Both-lung V20 was 33%, 25% and 35.3%, against stated limits of mean lung dose under 18 Gy and V20 under 35%.
  • Both-lung V5 was 64.7%, 44.1% and 62.57% for Patients 1, 2 and 3. The stated limit was under 60%.
  • In the planning comparison, mean lung dose with IMRT versus 4-arc VMAT was 18.9 vs 17.9 (Patient 1), 12.5 vs 14.7 (Patient 2) and 19.6 vs 21.4 (Patient 3). The authors reported no significant advantage for either technique.
  • The authors reported that CPAP inflated the chest, moved the heart and liver away from the radiation fields, and increased lung volume. This was shown only in figures, without numbers.
• The authors' conclusion: The authors concluded that radiotherapy is effective for pleural mesothelioma and can offer long-term local control. They also concluded that CPAP may improve dosimetry and reduce toxicity and should be further explored.

Topics

Medical terms in this study, explained in our Lexicon: Diaphragm, Pleural Mesothelioma.

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