Stereotactic Radiosurgery and Fractionated Stereotactic Radiosurgery in Patients with Recurrent Glial Tumors

Abstract

To evaluate stereotactic radiosurgery/fractionated stereotactic radiosurgery (SRS/fSRS) treatment outcomes of recurrent glial tumor patients who were previously treated with surgery and radiotherapy and who were not candidate for re-surgery. Thirty-one recurrent glial tumor patients treated with Cyberknife (AccurayIncorporated, Sunnyvale, CA, USA) were prospectively evaluated. The endpoints of the study were overall survival after the first diagnosis, overall survival after re-irradiation, and the parameters that affect them. Acute and chronic side effects related to the treatment were recorded. The median time between first radiotherapy and reirradiation was 26 months (range, 4-232 months). After the first radiation treatment, 27 (%87) patients relapsed in the primary radiotherapy region. A median total dose of 30 Gy (range, 18-40 Gy) was delivered in median fractions of 5 (range, 1-5 fraction) with CyberKnife. The Median follow-up was 12 months (6-37 months). The median tumor volume was 13 cc (range, 6-100 cc). The median overall survival after reirradiation was 15 months (range, 6-33 months). All the patients who developed grade 4 radionecrosis had tumor volumes greater than 25 ml. In multivariate analysis, only tumor volume (>= 15 ml vs. < 15 ml) was found to be a statistically significant independent predictor for survival after reirradiation (p=0.015). Large irradiation volumes increase radionecrosis risk and decrease tumor control probability. SRS/fSRS is safe and may be an effective treatment option for selected recurrent high-grade glioma patients with small focal tumors.