A pilot trial of high-dose-rate intraoperative radiation therapy for malignant pleural mesothelioma

PURPOSE: To report results of a phase II trial of high-dose-rate intra-operative radiation therapy (HDR-IORT) for malignant pleural mesothelioma (MPM). METHODS AND MATERIALS: Seven patients had extrapleural pneumonectomy with IORT (EPP/IORT) and 6 patients had pleurectomy/decortication with IORT (PD/IORT) between 1994 and 1996. IORT was delivered with ¹⁹²Ir using a customized applicator with a remote afterloader. A median of 3 sites were treated to a median area of 143 cm². A dose of 1500 cGy was prescribed at each site, with 1000 cGy delivered to the mediastinum. Postoperative external beam radiation therapy (EBRT) was given 3-5 weeks later. Median follow-up was 8 months (range, 1-84 months). RESULTS: Five patients developed local failure. Two-year local control and survival rates were 35% and 23%, respectively. Mortality was 2/13 (15%), 1 from each surgical group. Serious complications requiring further intervention occurred in 3/6 (50%) of the EPP/IORT group and 1/5 (20%) of the PD/IORT group. CONCLUSIONS: HDR-IORT after EPP for MPM is prohibitively toxic and has been abandoned, while its use with PD remains in question.