CCKBR and cancer: Even though CCK2R could not be correlated with patient pathological data [2, 7, 9, 11, 14, 37], the previously reported overexpression of CCK2R on certain cancers [4, 6, 7, 8, 23] still promoted exploration of its use for delivery of ligand-targeted cancer imaging agents [19, 24–36, 38, 39].