Background
Retrospective multicenter cohort (International Radiosurgery Research Foundation). N=512 nonfunctioning pituitary adenomas (NFPA) treated with Gamma Knife SRS, all after prior transsphenoidal surgery (adjuvant for residual/recurrent disease). Median tumor volume 2.9 cm³.
Interventions and follow up
Treatment: Gamma Knife SRS for NFPA after prior transsphenoidal surgery (median tumor volume 2.9 cm³)
Primary endpoint: 5-yr tumor control; new endocrine deficit; new visual deficit
mFollow up: Median 55.6 mo
Primary endpoint: 5-yr tumor control; new endocrine deficit; new visual deficit
mFollow up: Median 55.6 mo
Results
5-yr tumor control (no progression): 93%
New hypopituitarism after SRS: 27% at 5 yr
New visual deficit: 4.7%
Smaller volume (≤4 cm³): Associated with lower hypopituitarism risk
New hypopituitarism after SRS: 27% at 5 yr
New visual deficit: 4.7%
Smaller volume (≤4 cm³): Associated with lower hypopituitarism risk
Adverse events
New endocrine deficiency (any axis): 27% at 5 yr (GH most common)
New cranial nerve palsy: 2.1%
New visual field defect: 4.7% (higher optic apparatus dose)
Deaths / radiation-induced neoplasia: None in cohort
New cranial nerve palsy: 2.1%
New visual field defect: 4.7% (higher optic apparatus dose)
Deaths / radiation-induced neoplasia: None in cohort
Conclusions
SRS achieves 93% 5-yr tumor control for residual/recurrent NFPA after transsphenoidal surgery, with new hypopituitarism in 27% and visual deficit in 4.7%. Larger tumor volume and higher optic-apparatus dose are key adverse prognostic factors.
Key Limitations
Retrospective multicenter pooling with variable technique/dose; no comparator arm; endocrine assessment heterogeneity across centers; limited long-term ('beyond 5 yr) visual/cognitive data.
Clinical Context
One of the largest multicenter NFPA SRS series; supports adjuvant SRS for residual/recurrent NFPA and informs dose constraints to the optic apparatus.