Conventional pituitary irradiation is effective in normalising plasma IGF-I in patients with acromegaly.
OBJECTIVE
For patients in whom acromegaly persists despite pituitary surgery, conventional pituitary irradiation represents an additional treatment option. A 30-60% cure rate is described in the literature, but these studies did not utilise strict rules of remission, such as "safe" GH levels <2.5 microg/l, and age-adjusted normal IGF-I levels.


METHODS
We report the outcome of 41 patients with acromegaly who received pituitary conventional external irradiation. The median follow-up time was 12.8 years (3.7-43.4 years) post-radiotherapy.


RESULTS
The median pre-irradiation GH level was 31.0 microg/l (7.0-210 microg/l). Information on IGF-I levels was only available for 6 patients prior to therapy. Utilising strict rules of remission, one-third (14/41) of our patients had normal biochemical parameters, i.e. "safe" GH (0.5 microg/l (range 0.2-1.6 microg/l)) and normal age-adjusted IGF-I levels (multiple of upper limit of normal range (xULN); 0.45 (0.2-1.0)) at the end of the follow-up period. An additional 9 patients achieved normal levels with adjunctive drug therapy. Furthermore, disease activity was reduced in a considerable proportion of the 18 patients who did not achieve normal biochemical levels (GH: 3.6 microg/l (1.9-15.7 microg/l); xULN of IGF-I: 1.6 (0.9-2.6)). In retrospect, remission is unlikely in patients who had a GH level greater than 52 microg/l (mean+2 s.d. of cured patients) prior to radiotherapy. In addition to the 12 patients with pre-irradiation pituitary functional deficiency, another 11 patients developed symptoms of panhypopituitarism during the 3-year period following irradiation. Within a 6-year period, partial pituitary insufficiency was observed in a further 7 patients, thus necessitating hormone substitution treatment.


CONCLUSIONS
Using strict rules of remission, in our cohort we found both a normalisation of IGF-I and safe GH levels in 34% of patients treated for acromegaly with conventional irradiation therapy.
Gutt
B
B
Department of Internal Medicine, Medizinische Klinik Innenstadt, University of Munich, Ziemssenstrasse 1, D-80336 Munich, Germany.
Hatzack
C
C
Morrison
K
K
Pöllinger
B
B
Schopohl
J
J
D000172:Acromegaly / Q000097:blood* / Q000503:physiopathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D010902:Pituitary Gland / Q000528:radiation effects*; D010903:Pituitary Gland, Anterior / Q000503:physiopathology; D012016:Reference Values; D012189:Retrospective Studies
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I