Conventional pituitary irradiation is effective in normalising plasma IGF-I in patients with acromegaly

Department of Internal Medicine, Medizinische Klinik Innenstadt, University of Munich, Ziemssenstrasse 1, D-80336 Munich, Germany.

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. DESIGN AND 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. CONCLUSION: 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.

This article has been cited by other articles:

				M. Losa, L. Gioia, P. Picozzi, A. Franzin, M. Valle, M. Giovanelli, and P. Mortini The Role of Stereotactic Radiotherapy in Patients with Growth Hormone-Secreting Pituitary Adenoma J. Clin. Endocrinol. Metab., July 1, 2008; 93(7): 2546 - 2552. [Abstract] [Full Text] [PDF]

				P. J. Jenkins, P. Bates, M. N. Carson, P. M. Stewart, J. A. H. Wass, and on behalf of the UK National Acromegaly Register S Conventional Pituitary Irradiation Is Effective in Lowering Serum Growth Hormone and Insulin-Like Growth Factor-I in Patients with Acromegaly J. Clin. Endocrinol. Metab., April 1, 2006; 91(4): 1239 - 1245. [Abstract] [Full Text] [PDF]

				C. A. Hurty and B. Flatland Feline Acromegaly: A Review of the Syndrome J. Am. Anim. Hosp. Assoc., September 1, 2005; 41(5): 292 - 297. [Abstract] [Full Text] [PDF]

				Z Merza Modern treatment of acromegaly Postgrad. Med. J., April 1, 2003; 79(930): 189 - 194. [Abstract] [Full Text] [PDF]