GRPR and breast cancer: Other molecular targets, such as the somatostatin receptor (SSTR), gastrin-releasing peptide receptor (GRPR), folate receptor (FR), C-X-C chemokine receptor type 4 (CXCR4), neuropeptide Y receptor Y1 (NPY1R) and vasoactive intestinal polypeptide receptor 1 (VIP-R1) have been previously evaluated for their potential for BC imaging (8, 9).