Gamma knife radiosurgery: a safe and effective salvage treatment for pituitary tumours not controlled despite conventional radiotherapy.
OBJECTIVE
We report the use of 'gamma knife' (GK) radiosurgery in 25 patients with pituitary adenomas not cured despite conventional therapy, including external beam radiotherapy.


METHODS
All patients had previously received conventional radiotherapy for a mean of 11.8 years prior to receiving GK; 23 out of 25 had also undergone pituitary surgery on at least one occasion. Seventeen had hyperfunctioning adenomas that still required medical therapy without an adequate biochemical control--ten somatotroph adenomas, six corticotroph adenomas and one prolactinoma, while eight patients had non-functioning pituitary adenomas (NFPAs).


RESULTS
Following GK, mean GH fell by 49% at 1 year in patients with somatotroph tumours. Serum IGF1 fell by 32% at 1 year and by 38% at 2 years. To date, 80% of the patients with acromegaly have achieved normalisation of IGF1, and 30% have also achieved a mean GH level of <1.8 ng/ml correlating with normalised mortality. A total of 75% NFPAs showed disease stabilisation or shrinkage post GK. The patient with a prolactinoma showed a dramatic response: 75% reduction in prolactin at 2 years, with a marked shrinkage on magnetic resonance imaging. The results in corticotroph adenomas were variable. Prior to GK, 72% of the patients were panhypopituitary, and 42% of the remainder have developed new anterior pituitary hormone deficiencies to date. No other adverse events have been detected at a mean follow-up of 36.4 months.


CONCLUSIONS
These data indicate that GK is a safe and effective adjunctive treatment for patients with NFPAs and acromegaly not satisfactorily controlled with surgery and radiotherapy.
Department of Oncology, Barts and the London NHS Trust, West Smithfield, London EC1A 7BE, UK.
F M
FM
Swords
J P
JP
Monson
G M
GM
Besser
S L
SL
Chew
W M
WM
Drake
A B
AB
Grossman
P N
PN
Plowman
D049913:ACTH-Secreting Pituitary Adenoma / Q000601:surgery; D000236:Adenoma / Q000601:surgery; D000328:Adult; D000368:Aged; D005260:Female; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000601:surgery; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000532:radiotherapy / Q000601:surgery*; D015175:Prolactinoma / Q000601:surgery; D016634:Radiosurgery; D016896:Treatment Outcome
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I