Long-Term Follow-Up Results of Postoperative Radiotherapy in 36 Patients with Acromegaly

In acromegaly, pituitary irradiation is a slow, but effective, intervention in decreasing GH concentration. Few studies addressing the outcome of radiotherapy have used the currently accepted strict criteria for remission in the analysis of data. These studies report a low percentage of remission after radiotherapy. Doubt has especially been raised as to whether radiotherapy is effective in normalizing serum insulin-like growth factor (IGF)-I concentration. We analyzed the long-term follow-up data of postoperatively administered radiotherapy in 36 patients with postoperative persistent acromegaly, using both the normalization of GH suppression during oral glucose loading (GTT) and the normalization of IGF-I concentration as criteria for remission. Before radiotherapy, mean suppressed GH was 9.8 ± 1.9 mU/L (n = 31), and mean IGF-I concentration was 44.3 ± 3.9 nmol/L, equivalent to + 4.76 ± 0.78 age-related IGF-I sd score (n = 13). The median radiation dose was 40 Gray (range, 25–50 Gray). At 5, 10, and 15 ...