Volumetric Modulated Arc Therapy after lung sparing surgery for malignant pleural mesothelioma: single institution experience

ABSTRACT Purpose s: to investigate the possible role of Volumetric Modulated Arc Therapy (VMAT) in the setting of adjuvant treatment for malignant pleural mesothelioma (MPM) treated with lung sparing surgery (P/D: pleurectomy/decortication). Materials and methods Patients affected by MPM treated with P/D and adjuvant RT with VMAT were included. Endpoints of the present analysis were local control (LC), progression free survival (PFS), and overall survival (OS). Assessment of variables impacting survival was performed with univariate and multivariate Cox proportional hazards models. Results Forty-nine patients were suitable for the analysis. 96% was treated with a trimodality approach. Radiotherapy was delivered to a median dose of 44 Gy in 22 fractions (range 22-59.4 Gy).Treatment was well tolerated with just two G3 acute toxicities recorded, one case of G5 and two cases of G4 toxicity during follow up. With median follow up of 27.4 months, local control at 12, 24, and 36 months was 75.2%, 67.4%, and 56.5%. Median progression free survival was 14.9 months (95% CI 7.5-25.2). Median OS was 21.5 months (95% CI 15.3-37.1). At multivariable analysis, the administration of Carboplatin instead of Cisplatin based chemotherapy [HR 2.97 (1.22-7.26), p=0.017] and R2 resection [HR 1.95 (1.27-2.99), p=0.002] showed a negative correlation with OS. At univariate analysis, median heart V20 and V30 were associated with the occurrence of late pneumonitis (p=0.018 and p=0.077). Conclusion VMAT is feasible in the setting of MPM after lung sparing surgery. Toxicity rates are reduced with this technique in comparison with historical data with older techniques. Local and distant failures remain a major issue to be addressed in future trials.