Somatostatin analogs in ectopic corticotropin production.

Eutopic corticotroph pituitary adenomas and adrenal cortisol-producing adenomas do not usually express somatostatin receptors. However, ectopic corticotropin (ACTH)-producing tumors often express somatostatin receptors. Thus, the octreoscan can detect and localize tumors in 80% of patients with ectopic ACTH syndrome, and so it can be used to differentiate between eutopic and ectopic ACTH-dependent bilateral adrenal hyperplasia. Octreotide therapy can produce a rapid and sustained reduction of ACTH and cortisol levels in patients with ectopic ACTH-dependent Cushing's syndrome and, in some, may be the only long-term therapy possible. Although no large series have been reported, a review of the literature reveals a large number of case reports that have demonstrated the effectiveness of octreotide.