Glioblastoma multiforme (GBM) is a devastating malignant brain tumor characterized by resistance to available therapeutic approaches and relentless malignant progression that includes widespread intracranial invasion, destruction of normal brain tissue, progressive disability, and death. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are increasingly used in patients with recurrent GBM to complement traditional treatments such as resection, conventional external beam radiotherapy, and chemotherapy. Both SRS and fSRT are powerful noninvasive therapeutic modalities well suited to treat focal neoplastic lesions through the delivery of precise, highdose radiation. Although no randomized clinical trials have been performed, a variety of retrospective studies have been focused on the use of SRS and fSRT for recurrent GBMs. In addition, state-of-the-art neuroimaging techniques, such as MR spectroscopic imaging, diffusion tensor tractography, and nuclear medicine imaging, have enhanced treatment planning methods leading to potentially improved clinical outcomes. In this paper the authors reviewed the current applications and efficacy of SRS and fSRT in the treatment of GBM, highlighting the value of these therapies for recurrent focal disease.

✓ Optic nerve sheath meningiomas (ONSMs) are benign lesions originating from the dural sheath of the optic nerve. Progressive growth can lead to gradual loss of vision and exophthalmos. Loss of vision following microsurgical resection is not uncommon, and although stereotactic fractionated radiotherapy can be a safe alternative to control tumor growth and preserve vision, it may also lead to complications. Frame-based stereotactic radiosurgery has only been rarely used because single-fraction high-dose treatments of intrinsic optic nerve lesions may induce unacceptably high toxicity. New frameless radiosurgery devices such as the robotic CyberKnife, an image-guided radiosurgery system, can provide the extremely tight conformality and submillimetric accuracy of frame-based systems combined with the possibility of delivering radiation in several sessions. In the present report the authors review the clinical presentation and management of ONSMs and describe their preliminary experience using multisession radiosurgery to treat these lesions.

Objective: To describe and synthesize the current stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) cost-effectiveness research to date across several common SRS and SBRT applications. Methods: This review was limited to comparative economic evaluations of SRS, SBRT and alternative treatments (e.g., other radiotherapy techniques or surgery). Based on PubMed searches using the terms, “stereotactic”, “stereotactic radiosurgery”, “stereotactic radiotherapy”, “stereotactic body radiotherapy”, “stereotactic body radiation therapy”, “stereotactic ablative radiotherapy”, “economic evaluation”, “quality adjusted life year (QALY)”, ”cost”, “cost effectiveness”, “cost utility” and “cost analysis”, published studies of cost-effectiveness and health economics were obtained. Included were articles in peer-reviewed journals that presented a comparison of costs between treatment alternatives from January 1997 to November 2012. Papers were excluded if they did not present cost calculations, therapeutic cost comparisons, or health economic endpoints. Results: Clinical outcomes and costs of SRS and SBRT were compared to other therapies for treatment of cancer in the brain, spine, lung, prostate and pancreas. Treatment outcomes for SRS and SBRT are usually superior or comparable, and cost-effective, relative to alternative techniques. Conclusion: Based on the review of current SRS and SBRT clinical and health economic literature, from a patient perspective, SRS and SBRT provide patients a clinically-effective treatment option, while from the payer and provider perspective, SRS and SBRT demonstrate cost-savings.

For decades since its introduction, stereotactic radiosurgery (SRS) was used only to treat intracranial lesions because intracranial targets could be immobilized and located relative to a rigid metal frame affixed to the patient's head. Lesions outside the head were generally not treated with SRS because it is difficult to immobilize extracranial lesions and to attach stereotactic frames elsewhere on the body. Advances in computerized image guidance and robotics allowed the development of systems, such as the CyberKnife SRS System (Accuray, Inc, Sunnyvale, CA), that could target intracranial lesions without the stereotactic frame. Enhancements have resulted in a radiation delivery system that can accurately deliver high-dose, focal radiation to lesions in the spine, chest, and abdomen, even if they move during respiration. In this review we will describe the technical features of frameless SRS systems and briefly review their application to treating intracranial and extracranial lesions, focusing in particular on spinal lesions.

BACKGROUND: Frameless, non-isocentric irradiation of an extended segment of the trigeminal nerve introduces new concepts in stereotactic radiosurgery for medically resistant trigeminal neuralgia (TN). OBJECTIVE: To report the results of the largest single-center experience about image-guided robotic radiosurgery for TN. METHODS: A cohort of 138 patients treated with CyberKnife® (Accuray Incorporated, Sunnyvale, California) radiosurgery with a minimum follow-up of 36 mo were recruited. Pain relief, medications, sensory disturbances, rate and time of pain recurrence were prospectively analyzed. RESULTS: Median follow-up was 52.4 mo; median dose 75 Gy; median target length 5.7-mm; median target volume 40 mm³; median prescription dose 60 Gy (80% isodose line). Actuarial pain control rate (Barrow Neurological Institute [BNI] class I-IIIa) at 6, 12, 24, and 36 mo were 93.5%, 85.8%, 79.7%, and 76%, respectively. Overall, 33 patients (24%) required a second treatment. Overall, 18.1% developed sensory disturbances after 16.4 ± 8.7 mo. One patient (0.7%) developed BNI grade IV dysfunction; 6 (4.3%) developed BNI grade III (somewhat bothersome) hypoesthesia after retreatment; BNI grade II (not bothersome) hypoesthesia was reported by 18 patients (11 after retreatment). Shorter nerve length (<6 mm vs 6 mm), smaller nerve volume (30 mm³), and lower prescription dose (58 Gy) were associated with treatment failure (P = .01, P = .02, P = .03, respectively). Re-irradiation independently predicted sensory disturbance (P < .001). CONCLUSION: Targeting a 6-mm segment of the trigeminal nerve with a prescribed dose of 60 Gy appears safe and effective. Persistent pain control was achieved in most patients with acceptable risk of sensory complications, which were typically found after re-irradiation.

✓ Radiosurgery plays an important role in the treatment of refractory seizures induced by hypothalamic hamartomas (HHs). These lesions, deeply located and surrounded by a delicate vascular and neuronal network, are often associated with catastrophic epilepsy leading to progressive cognitive and behavioral deterioration. Surgical approaches include microsurgical resection, endoscopic resection or disconnection, radiofrequency lesioning, and interstitial brachytherapy. Radiosurgery is an emerging treatment modality for HHs, which provides excellent seizure outcomes and no lasting complications to date.