Top Line: Is aggressive hemi-thoracic radiation beneficial for patients with malignant pleural mesothelioma (MPM) and unresectable or gross residual disease after surgery?
The Study: The goal of radiation as part of a multi-modality approach for MPM is to improve local control, but it is uncertain if the benefits outweigh potential pulmonary toxicity. Newer IMRT techniques better spare the lungs and may reduce such toxicity. In this single center, randomized trial, 220 patients with MPM were evaluated for radical hemi-thoracic IMRT. All patients had gross residual disease following either lung-sparing surgery (43%) or biopsy (57%), and all received adjuvant chemo (platinum/pemetrexed) prior to RT. Of those screened, 49% were eligible for randomization to either radical hemithoracic IMRT or palliative RT to gross disease. In the radical arm, 50 Gy in 25 fractions was delivered to a target encompassing all ipsilateral pleural surfaces (sans the interlobar pleura) with an SIB of 60 Gy to gross disease. Lung constraints were: contralateral V5<17% (mandatory) and total lung mean < 24 Gy (encouraged). Radical RT was associated with significantly longer median OS (12.4→ 25.6 months) and increased 2-year OS (28→ 58%). This appeared to be driven by a significant improvement in 2-year local control (27→ 83%). The rate of grade 2+ pneumonitis was 16%, and 15% of patients developed late grade 3+ dyspnea. Here’s a great expert opinion paper on RT for MPM.
TBL: This single-center trial suggests that hemi-thoracic IMRT (when feasible) after lung-sparing surgery and chemo for MPM improves local control and overall survival compared to palliative radiation. | Trovo, Int J Radiat Oncol Biol Phys 2020