Long-term Outcomes After Gamma Knife Stereotactic Radiosurgery for Nonfunctional Pituitary Adenomas

BACKGROUND: Nonfunctional pituitary adenomas (NFPAs) represent approximately 50% of all pituitary tumors. OBJECTIVE: To evaluate the long-term outcomes of stereotactic radiosurgery for NFPAs. METHODS: We evaluated the management outcomes of Gamma Knife radiosurgery in 125 patients with NFPAs over an interval of 22 years. The median patient age was 54 years (range, 16-88 years). One hundred ten patients (88%) had residual or recurrent tumors after >= 1 surgical procedures, and 17 (14%) had undergone prior fractionated radiation therapy. The median target volume was 3.5 cm(3) (range, 0.4-28.1 cm(3)), and the median tumor margin dose was 13.0 Gy (range, 10-25 Gy). RESULTS: Tumor volume decreased in 66 patients (53%), remained stable in 46 (37%), and increased in 13 (10.4%) during a median of 62 months (maximum, 19 years) of imaging follow-up. The actuarial tumor control rates at 1, 5, and 10 years were 99%, 94%, and 76%, respectively. Factors associated with a reduced progression-free survival included larger tumor volume (>= 4.5 cm(3)) and >= 2 prior recurrences. Of 88 patients with residual pituitary function, 21 (24%) suffered new hormonal deficits at a median of 24 months (range, 3-114 months). Prior radiation therapy increased the risk of developing new pituitary hormonal deficits. One patient (0.8%) had a decline in visual function, and 2 (1.6%) developed new cranial neuropathies without tumor progression. CONCLUSION: Stereotactic radiosurgery can provide effective management for patients with newly diagnosed NFPAs and for those after prior resection and/or radiation therapy.