Pituitary tumors are generally benign slow-growing neoplasms, and different adenomas show a typical pattern of SST receptor expression [74] according to the secreting cells from which they originate: GH-secreting pituitary adenomas mostly express sst2 and sst5 [147], ACTH-secreting lesions predominantly coexpress sst5 and sst2 [148] while in prolactinomas sst1 and sst5 are the predominant receptors [149]. This evidence concerns the gene SST and adenoma.