SSTR2 and neuroendocrine neoplasm: Specifically, OTR showed a trend towards higher relative expression in primary/metastasised gastroenteropancreatic neuroendocrine tumours versus normal tissue compared to the somatostatin receptor type 2 (SSTR2) [110], which is currently a known clinical ideal and successful receptor target for imaging and treatment displaying higher expression in tumour tissues with relatively low expression in the adjacent normal tissue.