title: Gamma knife radiosurgery for patients with nonfunctioning pituitary adenomas: results from a 15-year experience.
abstract: OBJECTIVE
  To evaluate the efficacy and complications of stereotactic radiosurgery for patients with nonfunctioning pituitary adenomas (NFA).
  
  
  METHODS
  This was a retrospective review of 62 patients with NFA undergoing radiosurgery between 1992 and 2004, of whom 59 (95%) underwent prior tumor resection. The median treatment volume was 4.0 cm(3) (range, 0.8-12.9). The median treatment dose to the tumor margin was 16 Gy (range, 11-20). The median maximum point dose to the optic apparatus was 9.5 Gy (range, 5.0-12.6). The median follow-up period after radiosurgery was 64 months (range, 23-161).
  
  
  RESULTS
  Tumor size decreased for 37 patients (60%) and remained unchanged for 23 patients (37%). Two patients (3%) had tumor growth outside the prescribed treatment volume and required additional treatment (fractionated radiation therapy, n = 1; repeat radiosurgery, n = 1). Tumor growth control was 95% at 3 and 7 years after radiosurgery. Eleven (27%) of 41 patients with normal (n = 30) or partial (n = 11) anterior pituitary function before radiosurgery developed new deficits at a median of 24 months after radiosurgery. The risk of developing new anterior pituitary deficits at 5 years was 32%. The 5-year risk of developing new anterior pituitary deficits was 18% for patients with a tumor volume of < or = 4.0 cm(3) compared with 58% for patients with a tumor volume >4.0 cm(3) (risk ratio = 4.5; 95% confidence interval = 1.3-14.9, p = 0.02). No patient had a decline in visual function.
  
  
  CONCLUSIONS
  Stereotactic radiosurgery is effective in the management of patients with residual or recurrent NFA, although longer follow-up is needed to evaluate long-term outcomes. The primary complication is hypopituitarism, and the risk of developing new anterior pituitary deficits correlates with the size of the irradiated tumor.
authors.affiliation: Department of Neurological Surgery, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. pollock.bruce@mayo.edu
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Pollock
authors.forename: Joseph
authors.initials: J
authors.lastname: Cochran
authors.forename: Neena
authors.initials: N
authors.lastname: Natt
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.forename: Dana
authors.initials: D
authors.lastname: Erickson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Link
authors.forename: Yolanda I
authors.initials: YI
authors.lastname: Garces
authors.forename: Robert L
authors.initials: RL
authors.lastname: Foote
authors.forename: Scott L
authors.initials: SL
authors.lastname: Stafford
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Schomberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007018:Hypopituitarism / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000473:pathology / Q000601:surgery*; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D047368:Tumor Burden