Volumetric Modulated Arc Therapy After Lung Sparing Surgery for Malignant Pleural Mesothelioma: A Single Institution Experience

Abstract

Introduction: We investigated the possible role of volumetric modulated arc therapy (VMAT) in the setting of adjuvant treatment of malignant pleural mesothelioma (MPM) after lung-sparing surgery with pleurectomy and decortication.

Materials and methods: Patients affected by MPM who had undergone pleurectomy and decortication and adjuvant radiotherapy with VMAT were included. The endpoints of the present analysis were local control, progression-free survival, and overall survival. Assessment of the variables affecting survival was performed using univariate and multivariate Cox proportional hazard models.

Results: A total of 49 patients were included in the present study. Of the 49 patients, 96% had been treated with a trimodality approach. Radiotherapy was delivered to a median dose of 44 Gy in 22 fractions (range, 22-59.4 Gy). The treatment was well tolerated, with just 2 grade 3 acute toxicities, 1 grade 5, and 2 grade 4 toxicities recorded during the follow-up period. The median follow-up period was 27.4 months. The local control rate at 12, 24, and 36 months was 75.2%, 67.4%, and 56.5%, respectively. The median progression-free survival was 14.9 months (95% confidence interval [CI], 7.5-25.2). The median overall survival was 21.5 months (95% CI, 15.3-37.1). On multivariate analysis, the administration of carboplatin- instead of cisplatin-based chemotherapy (hazard ratio, 2.97; 95% CI, 1.22-7.26; P = .017) and R2 resection (hazard ratio, 1.95; 95% CI, 1.27-2.99; P = .002) showed a negative correlation with overall survival. On univariate analysis, the percentage of the heart receiving >20 Gy and >30 was associated with the occurrence of late pneumonitis (P = .018 and P = .077).

Conclusion: VMAT is feasible in the setting of MPM after lung-sparing surgery. The toxicity rates were reduced with this technique compared with historical data of older techniques. Local and distant failure remain a major issue to be addressed in future trials.

Keywords: Adjuvant radiotherapy; Heart dose; Lung-sparing surgery; Malignant pleural mesothelioma; Volumetric modulated arc therapy.