SSTR2 and neuroendocrine neoplasm: Somatostatin analogues, such as octreotide, which display high binding affinity to SSTR2 and lower affinity to SSTR5 and SSTR3 (affinity rank order: SSTR2 > SSTR5 > SSTR3) are efficacious in the treatment of neuroendocrine tumors and exhibit only mild toxicity [139].