In support of this, in the phase III randomized PEONY trial of Asian patients with early/locally advanced HER2 breast cancer treated with pertuzumab plus trastuzumab and docetaxel, concomitant use of prophylactic granulocyte-colony stimulating factor was permitted, with only four patients (1.8%) reported to develop febrile neutropenia [19]. This evidence concerns the gene CSF3 and breast cancer.