Long term side effects after volumetric modulated arc therapy to the pleura in patients with malignant pleural mesothelioma.

PURPOSE

Lung-sparing pleurectomy/decortication (P/D) is the primary surgical approach for malignant pleural mesothelioma (MPM), and combining it with other therapies enhances patient outcomes.This report presents the extended follow-up results of MPM patients who underwent P/D and received volumetric modulated arc therapy (VMAT).

METHODS

From 2010 to 2021, 81 patients with biopsy-proven malignant pleural mesothelioma, all post-P/D with two intact lungs, were retrospectively analyzed. Some patients received either induction or post-radiation chemotherapy. The target volume was the entire hemithorax, excluding the ipsilateral lung, aiming for 50.4 Gy (1.8 Gy fractions), with a mean lung dose of <20 Gy. Kaplan-Meier analysis determined overall survival (OS) and progression-free survival (PFS). Pulmonary, cardiac, and gastrointestinal events (≥1 year follow-up) were scored using Common Terminology Criteria for Toxicity and Adverse Event Reporting version 5.0 (CTCAE V5.0).

RESULTS

Of the 81 patients, 45 (55.6 %) had ≥1 year of follow-up, median 2.2 years (26 months). Median OS was 14.2 months (95 % CI, 12.1-21) and PFS was 9.1 months (95 % CI, 7.7-12.5). The Kaplan-Meier OS rates were 60.5 % at 1 year, 33.3 % at 2 years; PFS rates were 40.7 % at 1 year, 19.8 % at 2 years. Seven patients (8.6 %) had grade 3 radiationpneumonitis, all resolving with care, and 1 patient experienced grade 3 pericarditis. No grade 3 gastrointestinal events occurred, and no grade 4 or 5 events were seen.

CONCLUSIONS

This study represents the largest retrospective cohort and longest follow-up to date assessing the safety of VMAT. Pleural VMAT proves safe, lacking unexpected long term severe side effects. Future research including treatment plan dose prediction, and advanced deployment techniques will aim to broaden mesothelioma radiotherapy delivery.