LINAC stereotactic radiosurgery booster following whole brain radiotherapy for cerebral metastases - a single centre experience

Abstract

INTRODUCTION: Whole brain radiotherapy (WBRT) either as an adjunct or sole treatment for cerebral metastases has been employed for over 50 years. Studies have compared the efficacy of WBRT when used as adjunct for open neurosurgery or radiosurgery or as a stand alone treatment. But not many studies have looked at the booster effect of radiosurgery. The aim of this study is to review the efficacy and safety of LINAC (LINear ACcelerator) based stereotactic radiosurgery for cerebral metastases after the administration of whole brain radiotherapy at a single institution. METHOD: Patients with history of cerebral metastases treated with WBRT and subsequent X-knife LINAC stereotactic radiosurgery booster were retrospectively reviewed over 8 years in a single institution. All patients were adults above 18 years of age. Patients with prior craniotomies were included. Different primary carcinomas were included. The dosages of radiotherapy, follow-ups, complications and survival were reviewed and presented in the study. RESULTS: From January 2004 to March 2012, 16 patients with cerebral metastases treated with WBRT received booster X-knife LINAC stereotactic radiosurgery to reccurrent or residual lesions were identified. All patients received standard WBRT treatment of 30 gray (Gy) in 10 fractions. X-knife therapy booster were given to 2 isocenters in 3 patients and single isocenters in other 13 patients. Radiosurgery booster were given from 1 month after WBRT to 21 months after WBRT. The dosage for X-knife booster ranged from 14 Gy at 85% isodose line to 20 Gy at 90% isodose line. Only one patient reported significant cerebral oedema as a result of the radiosurgery requiring steroid cover and the rest of the patients recorded no complication from radiosurgery. Follow-up period ranged from 3 months to 25 months following radiosurgery. Survival ranged from 5 months to 25 months after radiosurgery. CONCLUSION: Stereotactic radiosurgery booster can be safely administered to patients with cerebral metastatic lesions who have been treated with WBRT in the past. Radiosurgery booster in majority of the cases seem to offer effective local control of the disease with little risk of undesirable effects.