Impact of Neoadjuvant and Adjuvant Pleural Intensity-Modulated Radiotherapy in Multimodality Treatment for Malignant Pleural Mesothelioma.

Background: Few malignancies provoke as many controversies about treatment as pleural mesothelioma. There is limited experience with novel radiotherapy techniques worldwide in adjuvant and particularly in neoadjuvant settings within multimodality treatment. The objective of the current study was to investigate the long-term outcome of neoadjuvant and adjuvant pleural intensity-modulated radiotherapy (IMRT) combined with macroscopic complete resection with or without chemotherapy.

Methods: We retrospectively analyzed a consecutive cohort of 59 patients who were diagnosed with pleural mesothelioma and underwent multimodality treatment including macroscopic complete resection and neoadjuvant or adjuvant IMRT between 2005 and 2019 at the Department of Thoracic Surgery, Medical University of Vienna, Austria.

Results: In total, 59 patients (median age 59 years; IQR 54-66, male, n = 48; 81%) were included. Forty-seven patients underwent trimodality treatment consisting of induction chemotherapy, extrapleural pneumonectomy, and adjuvant IMRT. Novel neoadjuvant IMRT with (n = 9) or without (n = 3) chemotherapy followed by extrapleural pneumonectomy was performed in 12 patients. Median overall survival (OS) of all patients was 23.2 months (95% CI; 18.1-28.2) and 3- and 5-year survival rates were 33% and 28%, respectively. Survival was comparable between therapies including neoadjuvant versus adjuvant IMRT (median OS 17.5 vs. 24.0 months, p = 0.39).

Conclusions: Neoadjuvant pleural IMRT has been investigated as a novel treatment option for highly selected cases in pleural mesothelioma. Neoadjuvant IMRT was effective and safe in patients treated in a high-volume institution but showed no relevant survival benefit compared to adjuvant IMRT within multimodality treatment.