Pituitary tumor type affects the chance of biochemical remission after radiosurgery of hormone-secreting pituitary adenomas.
OBJECTIVE
Reported biochemical remission rates have ranged widely after stereotactic radiosurgery for patients with hormone-secreting pituitary adenomas. Confounding variables include histology, radiation dose, use of pituitary-suppressive medications, and length of follow-up.


METHODS
A retrospective review of 46 patients with pituitary adenomas (growth hormone-secreting, n = 27; prolactin-secreting, n = 11; adrenocorticotropin-secreting, n = 8) undergoing radiosurgery between January 1990 and December 2003 was conducted. All received a tumor margin dose of 18 Gy or more and were off pituitary-suppressive medications for at least 1 month before radiosurgery. The groups were similar with regard to irradiated volume, radiation dose, and follow-up. The median endocrinological follow-up after radiosurgery was 54 months.


RESULTS
The 4-year remission rates were 87% for patients with Cushing's disease, 67% for patients with acromegaly, and 18% for patients with prolactinomas. Patients with oversecretion of adrenocorticotropin or growth hormone were more likely to achieve remission after radiosurgery than patients with prolactinomas (hazard ratio, 4.4; 95% confidence interval, 1.1-18.2; P = 0.04). Of 44 patients with normal or partial anterior pituitary function before radiosurgery, 16 (36%) developed one or more new anterior pituitary deficits. The incidence of new anterior pituitary deficits was 26% at 4 years. No differences were noted in the incidence of new anterior deficits among the groups.


CONCLUSIONS
There seems to be a differential sensitivity after radiosurgery for hormone-secreting pituitary adenomas. Remission rates are greater for patients with Cushing's disease and acromegaly, whereas radiosurgery is less effective in achieving biochemical remission for patients with prolactinomas.
Pollock
Bruce E
BE
Departments of Neurological Surgery and Radiation Oncology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA. pollock.bruce@mayo.edu
Brown
Paul D
PD
Nippoldt
Todd B
TB
Young
William F
WF
D000236:Adenoma / Q000209:etiology / Q000378:metabolism* / Q000601:surgery*; D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010907:Pituitary Hormones / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000209:etiology / Q000378:metabolism* / Q000601:surgery*; D016634:Radiosurgery; D012074:Remission Induction; D012189:Retrospective Studies; D016896:Treatment Outcome
D010907:Pituitary Hormones