Treatment of pituitary-dependent Cushing's syndrome: long-term results of unilateral adrenalectomy followed by external pituitary irradiation compared to transsphenoidal pituitary surgery

Summary BACKGROUND The preferred treatment of Cushing's disease (CD) nowadays is transsphenoidal pituitary surgery (TPS). Prior to TPS, patients at the Leiden University Medical Centre were treated by unilateral adrenalectomy followed by external pituitary irradiation (UAPI). We report on long‐term results of both UAPl and TPS and compare remission, relapse rates, and complications. PATIENTS AND METHODS A retrospective Study was carried out on 130 patients with CD. Patients with pituitary macroadenoma were excluded. Eighty‐six and 44 patients underwent UAPl and TPS, respectively. Of these patients, 85 and 41 were evaluable for long‐term results. RESULTS Remission following UAPl and TPS was identical at 64% (54/85 and 27/41). Cumulative relapse was also comparable ‐ 17% (9/54) and 22% (6/27), respectively, ‐ for UAPl and TPS, although the mean follow‐up periods were different ‐ 21.4 years and 8.5 years, respectively. Cumulative disease‐free survival curves after UAPl and TPS are identical until 5 years of follow‐up, but diverge thereafter indicating more sustained remissions following UAPl (P=0.17, Wilcoxon statistic). Pituitary dysfunction following UAPl (36%) and pituitary surgery (55%) likewise did not dlffer significantly. However, pituitary dysfunction was an immediate event after TPS, whereas it developed after a mean interval of 17.8 years following UAPI. Low‐dose dexamethasone testing during follow‐up had no value in predicting therapeutic outcome. CONCLUSIONS The results of unilateral adrenalectomy followed by external pituitary irradiation do not Justify that this therapy is totally abandoned in favour of transsphenoidal pituitary surgery. Unilateral adrenalectorny followed by external pituitary irradiation is a valid therapeutic modality for the treatment of Cushing's disease, and could be considered as alternative to bilateral adrenalectomy and under some circumstances to transsphenoidal pituitary surgery.