Aim of this study was to investigate the diagnostic performance of [<sup>68</sup>Ga]Ga-FAPI-46 versus [<sup>18</sup>F]FDG PET/CT in patients with hormone-receptor and/or HER2-positive breast cancer, and to evaluate the uptake of both tracers stratified by molecular subtypes (luminal-like vs HER2-positive). This evidence concerns the gene ERBB2 and breast cancer.