Gamma knife radiosurgery for nonfunctioning pituitary adenomas.

The efficacy of gamma knife radiosurgery (GKS) for non-functioning pituitary adenomas (NPAs) has been assessed. Sixty patients with NPA were treated by GKS. Complete neurological and endocrinological follow-up information was available for 51 patients. Follow-up examinations included stereotactic magnetic resonance imaging for sequential measurements of the NPA volume. The median dose to the tumor margin was 16.5 Gy (range 11-20 Gy). The mean prescription isodose was 50% (range 45-75%). All patients underwent surgery for NPA before GKS. Fractionated radiotherapy was not applied. Median follow up after GKS was 21,7 months. Actuarial recurrence-free survival was 95% after three years with respect to a single GKS and 100% for patients who underwent repeated GKS. No neurological side effects were detected. Two patients developed new partial pituitary insufficiency after radiosurgery. Postoperative GKS for residual or recurrent small fragments of NPAs is an effective and safe treatment option. The follow-up examination for NPAs should include tumor volumetric analysis.