ERBB2 and breast cancer: The PHERGAIN 1 trial showed that, while 18fluorine-fluorodeoxyglucose positron emission tomography (FDG-PET) alone was ineffective at independently identifying responders to neoadjuvant trastuzumab/pertuzumab (HP) treatment in patients with early HER2+ breast cancer, about a third of responders to HP therapy (identified by FDG-PET) who also achieved a pCR post-treatment were able to forgo adjuvant TCHP chemotherapy.