High-dose-rate surface brachytherapy to boost elongated, curvilinear incisional scars after extrapleural pneumonectomy for malignant pleural mesothelioma treated with adjuvant intensity-modulated radiation therapy

Our plain-English summary of High-dose-rate surface brachytherapy to boost elongated, curvilinear incisional scars after extrapleural pneumonectomy for malignant pleural mesothelioma treated with adjuvant intensity-modulated radiation therapy, by L.A. Doyle, T.N. Showalter, M. Werner-Wasik, et al (Brachytherapy, 2010).

The study

• Authors: L.A. Doyle, T.N. Showalter, M. Werner-Wasik, B. Weksler, Y. Xiao, Y. Yu, A. Macrone, H. Liu, A. Harrison
• Journal: Brachytherapy
• Published: 2010;9(1):86-90
• Type of article: Case report
• Read it: PubMed · Publisher

Abstract

Purpose: Providing adequate dosimetric coverage of elongated, curvilinear incisions during adjuvant intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM) creates technical challenges. We explored high-dose-rate (HDR) surface brachytherapy to supplement dose to multiple curvilinear incisions. This modality circumvents the technical limitations of relying on multiple en face electron fields while minimizing dose to adjacent normal tissues.

Methods And Materials: A 59-year-old man presented with a left-sided, Stage III, T3N2M0, epithelioid MPM. After undergoing a left EPP, adjuvant IMRT was recommended to improve local control. An eight-field IMRT plan was designed to encompass the postoperative hemithorax. Incisional scars were lengthy and extended beyond the hemithoracic target volume. Both en face electron and surface HDR plans were prepared and evaluated based on dosimetric coverage of the incisional scars, dose to normal tissues, reliability of setup, and treatment delivery.

Results: HDR was preferred. The patient was planned and treated in the right lateral decubitus position. HDR source catheters were placed along the incisions atop 5-mm bolus. A composite plan including IMRT and brachytherapy dose contributions was produced. Boosts of incisional scars were performed in six fractions (three fractions per week) of 3 Gy prescribed to 12 mm from the catheter. HDR brachytherapy was well tolerated.

Conclusions: Surface HDR brachytherapy is a viable option for supplemental dose to incisional scars at risk of local recurrence after EPP for MPM. Advantages over electron beam therapy include avoidance of field abutments and feathering, less tissue-bone interface dose uncertainty and reproducibility of treatment delivery.

Copyright (c) 2010 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

In plain English

This case report described radiation treatment for one man, aged 59, with left-sided, Stage III epithelioid malignant pleural mesothelioma. The article did not discuss asbestos exposure. After extrapleural pneumonectomy, surgery removing the lung and its lining, he received intensity-modulated radiation therapy (IMRT), 54.0 Gy in daily 1.8-Gy doses. His two scars, 22 and 34 cm long, extended beyond the main radiation target. Dose readings taken along them during IMRT ranged from 1.0 to 1.7 Gy, below target. The team compared electron beam and surface high-dose-rate (HDR) brachytherapy plans and chose HDR. HDR gave six 3-Gy treatments through catheters laid along the scars. The six HDR treatments took about 270 minutes in total, versus 450 minutes for the 15-treatment electron course, which was not given. He developed Grade 2 dermatitis, which resolved. He then developed Grade 3 lung toxicity and died of pneumonitis the authors called likely treatment-related. They attributed the opposite-lung dose to IMRT, with negligible contribution from HDR. The authors concluded that surface HDR is an option for boosting dose to scars at risk of recurrence.

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: Case report (single patient), comparing two radiation planning approaches for boosting dose to surgical scars
• Who was studied: One 59-year-old man with left-sided, Stage III, T3N2M0 malignant pleural mesothelioma (epithelioid on surgical pathology) after extrapleural pneumonectomy, treated at Jefferson Medical College of Thomas Jefferson University, Philadelphia; dates of treatment not given
• Exposure: No asbestos exposure is described. The exposure studied was radiation treatment: IMRT prescribed to 54.0 Gy in 1.8-Gy daily fractions, plus a surface HDR brachytherapy boost to the incisional scars of six fractions of 3 Gy, prescribed to a point 12 mm from the catheter (a depth of 7 mm in tissue)
• Main results:
  • The incisional scars were 22 and 34 cm long and extended beyond the hemithoracic clinical target volume
  • MOSFET dose readings taken during IMRT along the two incisional scars were variable and below target dose, ranging from 1.0 to 1.7 Gy along the length of the incisions
  • The electron beam alternative would have required matching five fields across the two incisions
  • HDR was selected. Total setup and treatment time for the six HDR treatments given was approximately 270 minutes. The authors compared this with 450 minutes for the alternative course of 15 electron fractions, which was not delivered
  • The patient developed Grade 2 dermatitis about 1 week after completing treatment; it was treated with topical ointment and resolved within 1 month
  • The patient developed Grade 3 lung toxicity 5 weeks after completing radiation therapy
  • The patient died of pneumonitis, described by the authors as likely treatment-related, 3 weeks after presenting with the lung toxicity
  • The authors attributed the dose to the contralateral (right) lung to the IMRT, with negligible contribution from the HDR treatment
• The authors' conclusion: The authors concluded that surface HDR brachytherapy is an option for supplemental dose to incisional scars at risk of local recurrence after extrapleural pneumonectomy for malignant pleural mesothelioma. In their view, its advantages over electron beam therapy include avoiding multiple field abutments and feathering, less dose uncertainty at the tissue-bone interface, shorter treatment time and sparing of departmental resources
• Limitations the authors state:
  • The composite IMRT-plus-HDR plan did not account for biologic equivalent dose
  • The IMRT and HDR planning CT scans could not be fused because the patient's position was so different, so the HDR plan had to be reconstructed on the IMRT CT
  • Incisional dose from IMRT was not measured precisely enough to vary the HDR dose along the catheter length
  • Skin dose estimates in treatment planning systems may not be precise enough

Topics

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

Medical terms in this study, explained in our Lexicon: Brachytherapy, Extrapleural Pneumonectomy (EPP), Pleural Mesothelioma, Intensity-Modulated Radiation Therapy (IMRT), Epithelioid, Hemithorax.

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