89Zr-pertuzumab could recognize patients with HER2-positive breast cancer metastases whose primary tumors were HER2-negative, resulting in potential therapeutic effects.66,67 Since HER2-PET/TC assesses HER2 distribution among all metastatic sites simultaneously, it allows to overcome some limitations related to biopsies that, besides being more invasive procedures, permit to evaluate just one metastatic sample at a time. The gene discussed is ERBB2; the disease is breast cancer.