Because greater benefits from HER2-targeted neoadjuvant treatment in breast cancer are achieved in patients with small HR-negative tumors compared with patients with large HR-positive tumors (25), it is noteworthy that the capacity of the ATM rs11212617 C allele to predict a higher chance of achieving a pCR in patients treated with neoadjuvant metformin was not altered after accounting for factors like tumor size and HR status. The gene discussed is ERBB2; the disease is breast cancer.