WITHDRAWN: Micro-Multileaf Collimator LINAC Radiosurgery for Vestibular Schwannomas.
This study evaluates the efficacy of linear accelerator (LINAC) radiosurgery using micro multi-leaf collimator technique (μMLC) in the treatment of a consecutive series of patients with vestibular schwannomas.



In this retrospective study, we enrolled 50 patients with non-neurofibromatosis type 2 vestibular schwannoma who were treated with μMLC LINAC-based SRS at University Hospital of Cologne, Germany. A minimum clinical follow-up of 24 months was conducted. Thirty-nine out of the 50 tumors (78 %) were treated with μMLC LINAC as a primary treatment (a newly diagnosed tumor). The remaining 11 vestibular schwannomas (22%) were treated as a salvage treatment (5 patients with a residual tumor; and 6 patients with a recurrent tumor following a microsurgical resection). The median tumor volume was 1.4 ml. The median tumor surface dose, median maximal dose and median therapeutic isodose were 12 Gy, 16 Gy and 77% respectively.



Follow-up MR images showed that a tumor progression-free status was achieved for 95.7% of patients. Partial tumor shrinkage was observed after μMLC LINAC SRS for 21.3% of patients. No change in tumor size (a stable tumor) was noted for 74.5% of patients. Tumor progression was observed for 4.3% of patients. At the end of follow-up, the actuarial 5- year and 10 year progression-free survival after radiosurgery were both 95.7%.



LINAC radiosurgery using a micro multi-leaf collimator for vestibular schwannomas smaller than 3 cm is effective in yielding a high local tumor control, whereas the treatment-related morbidity remains low.
Department of Stereotaxy and Functional Neurosurgery, University Hospital of Cologne, Germany; Department of Neurosurgery, Faculty of Medicine, Tanta University, Egypt. Electronic address: essam.rezk@med.tanta.edu.eg.
Essam M
EM
Rezk
Department of Stereotaxy and Functional Neurosurgery, University Hospital of Cologne, Germany.
Faycal
F
El Majdoub
Department of Radiation Oncology, University Hospital of Cologne, Germany.
Martin
M
Kocher
Department of Stereotaxy and Functional Neurosurgery, University Hospital of Cologne, Germany.
Harald
H
Treuer
Department of Stereotaxy and Functional Neurosurgery, University Hospital of Cologne, Germany.
Volker
V
Sturm
Department of Stereotaxy and Functional Neurosurgery, University Hospital of Cologne, Germany.
Mohammad
M
Maarouf
LINAC radiosurgery; Micro-multi-leaf collimator; vestibular schwannomas; μMLC