title: Clinical analysis of spinal stereotactic radiosurgery in the treatment of neurogenic tumors.
abstract: OBJECTIVE
  In this study the authors sought to evaluate clinical outcomes after using stereotactic radiosurgery (SRS) to treat benign and malignant spinal neurogenic tumors.
  
  
  METHODS
  The authors reviewed a total of 66 procedures of spinal SRS performed between 2001 and 2013 for 110 tumors in 58 patients with spinal neurogenic tumors, which included schwannomas, neurofibromas, and malignant peripheral nerve sheath tumors (MPNSTs). The clinical and radiological findings were evaluated in patients with benign neurogenic tumors. For the 4 patients with MPNSTs, the authors reported overall survival and results of additional immunohistochemical staining to predict the survival difference among the patients.
  
  
  RESULTS
  Of the 92 benign neurogenic tumors, 65 tumors that were serially followed up using MRI after SRS showed significant change in mean tumor volume, from a mean of 12.0 ± 2.6 cm3 pre-SRS to 10.8 ± 2.5 cm3 post-SRS (p = 0.027), over an average of 44 months. The local control rate of benign neurogenic tumors was 95.4%. The 34 patients who presented with clinical symptoms of pain showed a significant symptomatic improvement. The initial mean visual analog scale (VAS) score was 6.0 and decreased dramatically to 1.0 after SRS during an average follow-up period of 10.9 months (median of 8.1 months). Although the proportions of transient swelling and loss of intramural enhancement were significantly different among the groups, there was no statistically significant correlation between those 2 factors and local tumor control (p = 0.253 and 0.067, respectively; Fisher's exact text). Cross-table analysis also indicated that there was no statistically significant relationship between groups with loss of intramural enhancement and transient swelling. The median survival of neurofibromatosis Type 1 (NF1)-related and sporadic MPNSTs was 1.13 and 5.8 years, respectively. Immunohistochemical results showed that S100 was expressed in a sporadic MPNST or neurofibroma, whereas topoisomerase-IIa was expressed in NF1-related MPNSTs.
  
  
  CONCLUSIONS
  SRS is an effective treatment modality for benign neurogenic tumors, while MPNSTs showed heterogeneity in their responses to SRS.
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Dong-Won
authors.initials: DW
authors.lastname: Shin
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Moon-Jun
authors.initials: MJ
authors.lastname: Sohn
authors.affiliation: Pathology, and.
authors.forename: Han-Seong
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Dong-Joon
authors.initials: DJ
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Asan Medical Center, College of Medicine, University of Ulsan, Seoul; and.
authors.forename: Sang Ryong
authors.initials: SR
authors.lastname: Jeon
authors.affiliation: Radiology, Inje University IIsan Paik Hospital, College of Medicine, Goyang;
authors.forename: Yoon Joon
authors.initials: YJ
authors.lastname: Hwang
authors.affiliation: Department of Life Science, The University of Seoul, Korea.
authors.forename: Eek-Hoon
authors.initials: EH
authors.lastname: Jho
mesh_terms: D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018317:Nerve Sheath Neoplasms / Q000473:pathology / Q000601:surgery*; D009442:Neurilemmoma / Q000473:pathology / Q000601:surgery; D009455:Neurofibroma / Q000473:pathology / Q000601:surgery*; D019635:Neurosurgical Procedures; D010147:Pain Measurement; D016634:Radiosurgery / Q000379:methods*; D013125:Spinal Neoplasms / Q000473:pathology / Q000601:surgery*; D015996:Survival Rate; D016896:Treatment Outcome
keywords: GTV = gross tumor volume; MPNST = malignant peripheral nerve sheath tumor; NF1 = neurofibromatosis Type 1; NF2 = NF Type 2; SRS = stereotactic radiosurgery; TOP2A = topoisomerase II alpha; VAS = visual analog scale; immunohistochemical staining; malignant peripheral nerve sheath tumor; neurofibromatosis; oncology; spinal neurogenic tumors; stereotactic spinal radiosurgery