GRPR and breast neoplasm: <h4>Purpose</h4>This study investigates the theranostic potential of a <sup>44/47</sup>Sc-labeled antagonist targeting the gastrin-releasing peptide receptor (GRPR) in prostate and breast tumors.<h4>Methods</h4>A statine-based GRPR antagonist (AAZTA<sup>5</sup>-Pip-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH<sub>2</sub>: LF1) was radiolabeled with scandium-44/47.