The authors report on a retrospective analysis of the imaging and clinical outcomes following gamma surgery in 100 patients with nonsecretory pituitary macroadenoma.
Between June 1989 and March 2004, 100 consecutive patients with nonsecretory pituitary macroadenoma were treated at the Lars Leksell Center for Gamma Surgery, University of Virginia Health System (Charlottesville, VA). Ninety-two patients had residual or recurrent macroadenoma following one or more surgical procedures. In eight patients, gamma surgery was the primary treatment. Ten patients received conventional fractionated radiotherapy before the gamma surgery. Sixty-nine patients required hormone replacement therapy for one or more deficits before gamma knife treatment. Peripheral doses between 5 and 25 Gy (mean 18.5 Gy) were administered.
Imaging and endocrinological follow-up evaluations were performed in 90 patients; these studies ranged from 6 to 142 months (mean 44.9 months) and 6 to 127 months (mean 47.9 months), respectively. Tumor volume decreased in 59 patients (65.6%), remained unchanged in 24 (26.7%), and increased in seven (7.8%). The minimal effective peripheral dose was 12 Gy; peripheral doses greater than 20 Gy did not seem to provide additional benefit. Of 61 patients with a partially or fully functioning pituitary gland and follow-up data, 12 (19.7%) suffered new hormone deficits following gamma surgery. In patients with endocrinological follow-up data that had been collected over more than 2 years, the rate of new deficits was 25%. No neurological morbidity or death was related to treatment.
Current experience suggests that gamma surgery is an appropriate means of managing recurrent or residual nonsecretory pituitary macroadenoma following microsurgery and a primary treatment in selected patients. To evaluate definite rates of recurrence and new endocrine deficiencies, long-term follow-up studies are needed.
Abbreviations used in this paper:CT = computerized tomography; GKS = gamma knife surgery; LINAC = linear accelerator; MR = magnetic resonance.
Address reprint requests to: Ladislau Steiner, M.D., Ph.D., Department of Neurological Surgery, Lars Leksell Center for Gamma Surgery, University of Virginia Health System, 1215 Lee Street, Room G-512, Charlottesville, Virginia 22908. email:
HoybyeCGrenbackERahnTDegerbladMThorenMHultingAL: Adrenocorticotropic hormone-producing pituitary tumors: 12 to 22-year follow-up after treatment with stereotactic radiosurgery. Neurosurgery49:284–2922001
McColloughWMMarcusRBJrRhotonALJrBallingerWEMillionRR: Long-term follow-up of radiotherapy for pituitary adenoma: the absence of late recurrence after greater than or equal to 4500 cGy. Int J Radiat Oncol Biol Phys21:607–6141991
MitsumoriMShrieveDCAlexanderEIIIKaiserUBRichardsonGEBlackPM: Initial clinical results of LINAC-based stereotactic radiosurgery and stereotactic radiotherapy for pituitary adenomas. Int J Radiat Oncol Biol Phys42:573–5801998
WebbKMLaurentJJOkonkwoDOLopesMBVanceMLLawsERJr: Clinical characteristics of silent corticotrophic adenomas and creation of an internet-accessible database to facilitate their multi-institutional study. Neurosurgery53:1076–10852003
WowraBStummerW: Efficacy of gamma knife radiosurgery for nonfunctioning pituitary adenomas: a quantitative follow up with magnetic resonance imaging-based volumetric analysis. J Neurosurg97:5 Suppl429–4322002