Intensity-modulated radiotherapy following extrapleural pneumonectomy for the treatment of malignant mesothelioma: clinical implementation

Abstract

Purpose: New insight into the extent of the target volume for the postoperative irradiation of malignant pleural mesothelioma as determined during surgery has indicated that standard conformal radiotherapy (IMRT) is not sufficient for curative treatment. We describe a novel technique for implementing intensity-modulated radiotherapy (IMRT) to deliver higher doses to treat the full extent of these complex target volumes.

Methods and materials: After extrapleural pneumonectomy, 7 patients underwent simulation, treatment planning, and treatment with IMRT to the involved hemithorax and adjacent abdomen. The target volumes encompassed the entire operative bed, including the ipsilateral mediastinum, anterior pleural reflection, and ipsilateral pericardium and the insertion of the diaphragm and crura. These were extensively marked during surgery with radiopaque markers to facilitate target delineation.

Results: Setup uncertainty and respiratory-dependent motion were found to be small. Coverage of the planning target volume was very good, with the crus of the diaphragm the most difficult volume to irradiate. The radiation doses to normal structures were acceptable.

Conclusion: IMRT for treatment of malignant mesothelioma after extrapleural pneumonectomy results in more potentially curative doses to large, complex target volumes with acceptable doses to normal tissues.