title: CyberKnife multisession stereotactic radiosurgery and hypofractionated stereotactic radiotherapy for perioptic meningiomas: intermediate-term results and radiobiological considerations.
abstract: Single fraction radiosurgery is conventionally precluded for lesions lying <2-3 mm of the anterior visual pathway because of the radiosensitivity of the optic nerve. We analyzed a series of 64 patients with "perioptic" meningiomas treated by CyberKnife multisession radiosurgery and hypofractionated stereotactic radiotherapy (hSRT). Between July 2007-May 2010, patients were treated using conventional multisession Cyberknife schemes (2-5 fractions) and results were retrospectively analyzed. A radiobiological model was then developed to estimate the best tumor control probability (TCP)/ normal tissue complication probability (NTCP) for these lesions. Resulting dose/fraction schemes were applied to patients treated between May 2010 and July 2014. Data were prospectively collected Twenty-five patients were included in the retrospective part of the study. Median tumor volume was 4.95 cc; median dose was 23.0 Gy and median number of fraction was 5 (range 2-5). No patient had visual deterioration at mean follow-up of 60 ± 12 months. Tumor control was achieved in all cases. Thirty-nine patients were treated according the radiobiology model and results prospectively analyzed. Median tumor volume was 7.5 cc, median dose 25.0 Gy and mean number of fraction 5 (range 3-15). No patient had visual deterioration or tumor progression at mean follow-up of 17 ± 10 months. Conventional multisession CyberKnife treatments (2-5 fractions) provided satisfactory results. Nonetheless, our estimation of TCP suggests the use of higher doses to grant long-term disease control. To achieve higher equivalent doses without significantly increasing the NTCP, we suggest the use of a greater number of fractions, moving to hSRT, in tumors in which the encasement of optic nerves is presumed.
authors: Department of Neurosurgery, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Alfredo
authors: A
authors: Conti
authors: Department of Radiation Oncology, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Antonio
authors: A
authors: Pontoriero
authors: Department of Medical Physics, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Federica
authors: F
authors: Midili
authors: Department of Radiation Oncology, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Giuseppe
authors: G
authors: Iatì
authors: Department of Medical Physics, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Carmelo
authors: C
authors: Siragusa
authors: Department of Oncology, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Chiara
authors: C
authors: Tomasello
authors: Department of Neurosurgery, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Domenico
authors: D
authors: La Torre
authors: Department of Neurosurgery, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Salvatore M
authors: SM
authors: Cardali
authors: Department of Radiation Oncology, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Stefano
authors: S
authors: Pergolizzi
authors: Department of Radiation Oncology, University of Messina, AOU "Policlinico G. Martino", Via Consolare Valeria 1, 98125 Messina, Italy.
authors: Costantino
authors: C
authors: De Renzis
keywords: CyberKnife; Hypofractionated stereotactic radiotherapy; Meningioma; Radiation induced optic neuropathy; Radiobiology