This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Powell, J. S. Articles by Freda, P. U. Search for Related Content PubMed PubMed Citation Articles by Powell, J. S. Articles by Freda, P. U.

Outcome of Radiotherapy for Acromegaly Using Normalization of Insulin-Like Growth Factor I to Define Cure¹

Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032; and Department of Neurosurgery, Mount Sinai Medical Center, New York, New York 10029

Address all correspondence and requests for reprints to: Dr. Pamela U. Freda, Department of Medicine, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, New York 10032.

Abstract

Radiation therapy (RT) has traditionally been considered a useful additional therapy for patients with acromegaly not achieving biochemical remission after surgery. However, recent evidence has suggested that RT is not curative in most patients with acromegaly when normalization of the serum insulin-like growth factor I (IGF-I) level is used to define remission. Therefore, we evaluated the success of RT based on IGF-I level in the 47 patients who received RT as part of their treatment from the cohort of 161 patients with acromegaly seen by us between 1981 and 1999. Four patients in whom no post-RT IGF-I level was available were excluded from the analysis. Of the remaining 43 patients, 32 patients received external beam RT, 6 received fractionated stereotactic radiosurgery, 4 received -knife RT, and 1 received proton beam RT. The most recent IGF-I levels in these 43 patients, obtained a mean of 5.2 yr post-RT (range, 0.8–13.2 yr), were compared to age-adjusted normal ranges.

IGF-I levels were normal in 17 patients (39.5%) without the addition of medical therapy. The percentage of patients with a normal IGF-I level generally increased with time post-RT; 27% of patients less than 6 yr post-RT, but 69.2% of patients 6 yr or more post-RT had normal IGF-I levels. Using the more traditional criterion for cure, a random GH measurement, 74% of patients had a GH level below 5 ng/mL, and 44% had a GH level below 2.5 ng/mL and would have been considered in remission based on these criteria.

We conclude that with time RT remains a useful adjunctive treatment for many patients with acromegaly. RT should be considered along with appropriate medical therapy in selected patients who do not achieve normalization of IGF-I level after surgery or for those resistant to medical therapy.

This article has been cited by other articles:

				K Mullan, C Sanabria, W P Abram, E M McConnell, H C Courtney, S J Hunter, D R McCance, H Leslie, B Sheridan, and A B Atkinson Long term effect of external pituitary irradiation on IGF1 levels in patients with acromegaly free of adjunctive treatment Eur. J. Endocrinol., October 1, 2009; 161(4): 547 - 551. [Abstract] [Full Text] [PDF]

				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. Abrams, O. Alexopoulou, R. Abs, D. Maiter, and J. Verhelst Optimalization and cost management of lanreotide-Autogel therapy in acromegaly Eur. J. Endocrinol., November 1, 2007; 157(5): 571 - 577. [Abstract] [Full Text] [PDF]

				S. Melmed Acromegaly N. Engl. J. Med., December 14, 2006; 355(24): 2558 - 2573. [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]

				A. F. Muller, J. J. Kopchick, A. Flyvbjerg, and A. J. van der Lely Growth Hormone Receptor Antagonists J. Clin. Endocrinol. Metab., April 1, 2004; 89(4): 1503 - 1511. [Full Text] [PDF]

				A. Colao, D. Ferone, P. Marzullo, and G. Lombardi Systemic Complications of Acromegaly: Epidemiology, Pathogenesis, and Management Endocr. Rev., February 1, 2004; 25(1): 102 - 152. [Abstract] [Full Text] [PDF]

				N. R. Biermasz, A. M. Pereira, M. Frolich, J. A. Romijn, J. D. Veldhuis, and F. Roelfsema Octreotide represses secretory-burst mass and nonpulsatile secretion but does not restore event frequency or orderly GH secretion in acromegaly Am J Physiol Endocrinol Metab, January 1, 2004; 286(1): E25 - E30. [Abstract] [Full Text]

				D. R. Clemmons, K. Chihara, P. U. Freda, K. K. Y. Ho, A. Klibanski, S. Melmed, S. M. Shalet, C. J. Strasburger, P. J. Trainer, and M. O. Thorner Optimizing Control of Acromegaly: Integrating a Growth Hormone Receptor Antagonist into the Treatment Algorithm J. Clin. Endocrinol. Metab., October 1, 2003; 88(10): 4759 - 4767. [Abstract] [Full Text] [PDF]