SSTR5 and neuroendocrine neoplasm: Their study exclusively focused on SSTR-2a, which is only one of the clinically relevant somatostatin receptors.15 This was preceded by a study in 2009 by Corleto et al, which focused on SSTR-2a and SSTR-5 expression in 33 cases of neuroendocrine tumors, not exclusive to PNETs.