Conventional Pituitary Irradiation Is Effective in Lowering Serum Growth Hormone and Insulin-Like Growth Factor-I in Patients with Acromegaly

• Published in: The journal of clinical endocrinology and metabolism Vol. 91; no. 4; pp. 1239 - 1245
• Main Authors: Jenkins, P. J., Bates, P., Carson, M. N., Stewart, P. M., Wass, J. A. H.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01-04-2006
• Subjects: Acromegaly - metabolism; Acromegaly - radiotherapy; Adolescent; Adult; Aged; Aged, 80 and over; Biological and medical sciences; Endocrinopathies; Female; Fundamental and applied biological sciences. Psychology; Human Growth Hormone - blood; Humans; Hypopituitarism - etiology; Hypothalamus. Hypophysis. Epiphysis (diseases); Insulin-Like Growth Factor I - metabolism; Male; Medical sciences; Middle Aged; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Pituitary Gland - metabolism; Pituitary Gland - radiation effects; Pituitary Hormones - blood; Radiotherapy - adverse effects; Retrospective Studies; Treatment Outcome; Vertebrates: endocrinology; Endocrinopathy; Human; Endocrine gland; Diseases of the osteoarticular system; Somatotropin hormone; Acromegaly; Insulin like growth factor 1; Adenohypophyseal hormone; Efficiency; Pituitary diseases; Irradiation; Serum; Endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2005-1616

Background: There has been recent controversy as to the effectiveness of conventional pituitary irradiation in reducing circulating GH levels to less than 2.5 ng/ml and/or normalization of serum IGF-I.
Objectives: Our objectives were to determine the effects of conventional pituitary irradiation on 1) lowering of serum GH and IGF-I levels, 2) the proportion of patients who achieve a GH level less than 2.5 ng/ml and a normal age-corrected IGF-I and the time taken to achieve this, and 3) the incidence of hypopituitarism and other adverse effects.
Design: We conducted retrospective data collection from 14 centers throughout the United Kingdom.
Patients: We studied 1840 patients with acromegaly, of whom 884 had received conventional pituitary irradiation.
Measurements: We assessed circulating GH and IGF-I levels and pituitary function at intervals after irradiation.
Results: Mean GH levels declined from 13.5 to 5.3 ng/ml at 2 yr after irradiation, to 2.0 ng/ml by 10 yr, and to 1.1 ng/ml at 20 yr. Twenty-two percent of patients achieved a level less than 2.5 ng/ml by 2 yr, 60% by 10 yr, and 77% by 20 yr. The interval to achieve this depended on the preirradiation GH level. IGF-I levels fell in parallel to those of GH with 63% of patients having a normal level by 10 yr. The proportions of patients with new pituitary hormone deficiencies 10 yr after irradiation were 18% for LH/FSH, 15% for ACTH, and 27% for TSH. No other side effects were noted.
Conclusions: In this, the largest series reported, conventional pituitary irradiation is shown to be an effective and safe means of reducing both serum GH and IGF-I concentrations in patients with acromegaly.