The Role of Radiotherapy in Acromegaly

Abstract

uniform radiotherapy technique was used in this retrospective study. Both proton beam radiotherapy and conventional radiation techniques were used, and patients were treated in several centers. The relatively low number of subjects in this study and the variability of the IGF-I assays used make it hard to draw final conclusions. In our own database, we looked for the course of serum IGF-I concentrations in acromegalic patients. In a group of 37 patients who were not cured after transsphenoidal surgery and radiotherapy and who could be followed for a period of 7 yr, we found that IGF-I concentrations had not normalized, even after a follow-up period of 7 yr. In the same group, anterior pituitary insufficiency had developed in about 40% (39% thyroidal insufficiency; 33% gonadal insufficiency; 42% adrenal insufficiency). This clearly demonstrates that pituitary damage frequently occurs after radiotherapy. The lowering of GH levels further supports the damaging effect of radiotherapy on the pituitary fossa. Why then do serum IGF-I concentrations not normalize, and what does this mean from a clinical