Somatostatin analogs in treatment of non-growth hormone-secreting pituitary adenomas.

Besides well-known effects in GH-secreting adenomas, somatostatin analogs such as octreotide and lanreotide have been used in TSH-secreting adenomas and in the so-called clinically nonfunctioning adenomas. The rationale for their use is based on the evidence that both these tumor types express large amounts of somatostatin receptor subtypes 2 and 5, which are preferentially bound by octreotide and lanreotide. However, whether in TSH-secreting adenomas the results are excellent in the nonfunctioning type, the results are controversial. Some preliminary results showing a very rapid recovery of the visual field have not been confirmed subsequently. No evident effect of tumor shrinkage has been reported. At present, the use of somatostatin analogs in clinically nonfunctioning adenomas is questioned.