Combined proton and photon conformal radiotherapy for intracranial atypical and malignant meningioma.

Abstract

To evaluate retrospectively the efficacy of conformal fractionated radiotherapy combining proton and photon beams after primary surgery for treatment of atypical and malignant meningiomas. Between September 1999 and October 2006, 24 patients (12 male, 12 female) with histopathologically proven meningioma (atypical 19, malignant 5) received postoperative combined radiotherapy with a 201-MeV proton beam at the Centre Protontherapie d'Orsay and a high-energy photon beam. Six patients underwent gross total resection and 18 a subtotal resection. Median gross tumor volume and clinical target volume were 44.7 cm(3) and 153.3 cm(3), respectively. Mean total irradiation dose was 65.01 CGE (cobalt gray equivalent), with a mean proton total dose of 34.05 CGE and a mean photon total dose 30.96 CGE. The median (range) follow-up interval was 32.2 (1-72) months. The overall mean local relapse-free interval was 27.2 (10-50) months, 28.3 (10-50) months for atypical meningioma and 23 (13-33) months for malignant meningioma. Ten tumors recurred locally. One-, 2-, 3-, 4-, 5-, and 8- year local control rates for the entire group of patients were 82.9% +/- 7.8%, 82.9% +/- 7.8%, 61.3% +/- 11%, 61.3% +/- 11%, 46.7% +/- 12.3%, and 46.7% +/- 12.3%, respectively. One-, 2-, 3-, 4-, 5-, and 8- year overall survival rates were 100%, 95.5% +/- 4.4%, 80.4% +/- 8.8%, 65.3% +/- 10.6%, 53.2% +/- 11.6%, and 42.6% +/- 13%, respectively. Survival was significantly associated with total dose. There was no acute morbidity of radiotherapy. One patient developed radiation necrosis 16 months after treatment. Postoperative combination of conformal radiotherapy with protons and photons for atypical and malignant meningiomas is a well-tolerated treatment producing long-term tumor stabilization.