Long-term outcomes Following Gamma Knife Radiosurgery For Patients with a Nonfunctioning Pituitary Adenoma

Jason P. Sheehan, PhD1, Rupa Gopalan2, David Schlesinger3, Mary Lee Vance2

1Department of Neurosurgery, University of Virginia 2University of Virginia, Charlottesville, Virginia, USA 3Charlottesville, United States

Keywords: pituitary adenoma, brain tumor, radiosurgery, gamma knife, outcome

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     Nonfunctioning pituitary adenomas recur after microsurgery. Gamma Knife radiosurgery (GKRS) has been used to treat recurrent adenomas.  
     This study evaluates the long term rates of tumor control and development of hypopituitarism in patients with nonfunctioning pituitary adenomas after GKRS.
Forty-eight patients with a nonfunctioning pituitary adenoma treated between 1991 and 2004 at the University of Virginia were studied. All patients had greater than 4 years of clinical and imaging follow-up.
     We reviewed the clinical and imaging records in our patient series.
     All patients underwent follow-up imaging and endocrine evaluations with duration ranging from 50 to 215 months (median 80.5) and 57 to 201 (median 95), respectively. New hormone deficiency after GKRS occurred in 19 of 48 patients (39%). Eight percent of patients developed ACTH/cortisol deficiency, 20.8% thyroid hormone deficiency, 4.2% gonadotropin deficiency, 16.7% growth hormone/IGF-1, and 2% diabetes insipidus. One patient developed panhypopituitarism including diabetes insipidus. Overall, control of tumor volume was 83%. Tumor volume decreased in 36 patients (75%), increased in eight patients (17 %), and was unchanged in four patients (8%). Tumor volumes greater than 5cc at the time of GKRS were associated with a significantly greater rate of growth (p=.003) compared with an adenoma with a volume of less than or equal to 5cc.
     This was a retrospective study without a control group.
     GKRS resulted in a high and durable rate of tumor control in patients with a nonfunctioning pituitary adenoma. A higher preoperative tumor volume was associated with an increased rate of tumor growth. 
     Although likely underreported in series with shorter follow-up, our higher incidence of long-term hypopituitarism following radiosurgery underscores the need for careful endocrine follow-up and appropriate hormone replacement.


Project Roles:

J. Sheehan (), R. Gopalan (), D. Schlesinger (), M. Vance ()