MRI tumor response and clinical outcomes after LINAC radiosurgery on 50 patients with recurrent malignant gliomas

The place of radiosurgery (RS) as an option in the treatment of recurrent malignant glioma is still debated on in the absence of prospective randomized trials.To assess the clinical outcome and MRI response after radiosurgery of recurrent malignant glioma.We evaluated 50 consecutive patients treated in a single institution. Between 2001 and 2008, 34 glioblastoma (GBM) and 16 anaplastic oligodendroglioma (AO) patients were treated with linear accelerator (Linac) RS for recurrence.The median marginal dose was 15 Gy and the median gross tumor volume (GTV) was 6.64 ml. No patient had acute (3 months) neurological morbidity after RS. Ten patients (20%) were reoperated on after RS, histopathological findings included necrosis alone in 3 cases (6%). The median overall survival was 21.5 months for GBM and 57.9 months for AO. The median survival after RS was 9.5 months for GBM and 32.9 months for AO. The median progression-free survival after RS was 6.7 months for GBM and 18 months for AO. MRI volume modifications after RS showed a transitory reduction or stabilization of disease linked to significantly improved survival in 58.8% of patients with GBM, 81.1% of patients with AO. Pathological subtype (AO versus GBM), MRI response, KPS70, marginal dose13 Gy, largest diameter of GTV25 mm and GTV7 ml were the main prognostic factors, associated with improved survival or PFS from RS.The magnitude of the survival increase compared to historical RPA classes may not be due to selection bias alone. Linac RS in selected patients with recurrent malignant glioma was well tolerated, effective and can be considered as one of several re-treatment options.