Radiosurgery of growth hormone-producing pituitary adenomas: factors associated with biochemical remission.
OBJECTIVE
The authors reviewed outcomes after stereotactic radiosurgery for patients with acromegaly and analyzed factors associated with biochemical remission.


METHODS
Retrospective analysis was performed for 46 consecutive cases of growth hormone (GH)-producing pituitary adenomas treated by radiosurgery between 1991 and 2004. Biochemical remission was defined as a fasting GH less than 2 ng/ml and a normal age- and sex-adjusted insulin-like growth factor-I (IGF-I) level while patients were not receiving any pituitary suppressive medications. The median follow up after radiosurgery was 63 months (range 22-168 months). Twenty-three patients (50%) had biochemical remission documented at a median of 36 months (range 6-63 months) after one radiosurgical procedure. The actuarial rates of biochemical remission at 2 and 5 years after radiosurgery were 11 and 60%, respectively. Multivariate analysis showed that IGF-I levels less than 2.25 times the upper limit of normal (hazard ratio [HR] 2.9, 95% confidence interval [CI] 1.2-6.9, p = 0.02) and the absence of pituitary suppressive medications at the time of radiosurgery (HR 4.2, 95% CI 1.4-13.2, p = 0.01) correlated with biochemical remission. The incidence of new anterior pituitary deficits was 10% at 2 years and 33% at 5 years.


CONCLUSIONS
Discontinuation of pituitary suppressive medications at least 1 month before radiosurgery significantly improved endocrine outcomes for patients with acromegaly. Patients with GH-producing pituitary adenomas should not undergo further radiation therapy or surgery for at least 5 years after radiosurgery because GH and IGF-I levels continue to normalize over that interval.
Pollock
Bruce E
BE
Department of Neurological Surgery, Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA. pollock.bruce@mayo.edu
Jacob
Jeffrey T
JT
Brown
Paul D
PD
Nippoldt
Todd B
TB
D000172:Acromegaly / Q000097:blood / Q000601:surgery*; D000206:Actuarial Analysis; D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000097:blood / Q000601:surgery*; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007018:Hypopituitarism / Q000097:blood / Q000175:diagnosis; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000097:blood / Q000601:surgery*; D011183:Postoperative Complications / Q000097:blood / Q000175:diagnosis*; D016634:Radiosurgery; D012189:Retrospective Studies
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I