Gamma-knife surgery is effective in normalising plasma insulin-like growth factor I in patients with acromegaly.
OBJECTIVE
For patients in whom acromegaly persists despite pituitary surgery or drug treatment, gamma-knife surgery represents an additional treatment option. Considering carefully the different reported biochemical outcomes, the central point is whether gamma-knife radiosurgery has advantages compared to conventional radiotherapy or, furthermore, to newer medical therapies, such as long-acting somatostatin analogues or growth hormone receptor antagonists.


METHODS
We report the outcome of 44 patients with acromegaly, who received gamma-knife surgery with the Leksell gamma knife. The median follow-up time was 1.9 years (0.5-4.3 years) post-radiosurgery. 43 of 44 patients had previously undergone pituitary surgery.


RESULTS
Immediately prior to gamma-knife surgery, median xULN of patients' serum IGF-I was 1.9 times above upper limit of normal (range: 0.5-8.9 xULN [multiple of upper limit of normal range]). There was a significant decline of serum IGF-I at patients' final follow-up. We found a normal age-adjusted IGF-I in 21/44 patients (xULN of IGF-I<1). Furthermore, as the number of treated patients increased, we found an improvement in remission rate, which let us assume that there was a learning effect for the gamma-knife performing team over time. In addition, the median adenoma size decreased from 1.5 ml (0.1-6.9 ml) prior to gamma-knife therapy to 0.3 ml (no rest vol. detectable-2.4 ml) at patients' last visit.


CONCLUSIONS
We have shown that pituitary gamma-knife surgery is effective in lowering serum IGF-I levels. At the end of the follow-up period, 48 % of our cohort had normal age-adjusted IGF-I levels.
Gutt
B
B
Department of Internal Medicine Innenstadt, University of Munich, Munich, Germany. Bodo.Gutt@med.uni-muenchen.de
Wowra
B
B
Alexandrov
R
R
Uhl
E
E
Schaaf
L
L
Stalla
G K
GK
Schopohl
J
J
D000172:Acromegaly / Q000097:blood / Q000601:surgery*; D000236:Adenoma / Q000601:surgery; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000601:surgery; D016634:Radiosurgery; D012016:Reference Values; D012189:Retrospective Studies; D013997:Time Factors
D015415:Biomarkers; D007334:Insulin-Like Growth Factor I