In the randomized, double-blind OlympiA clinical trial, patients with pathogenic or likely pathogenic gBRCAm and non-metastatic, ERBB2-negative primary breast cancer were randomized to receive twice-daily oral olaparib or placebo for 1 year following completion of definitive local treatment and neoadjuvant or adjuvant chemotherapy (14). This evidence concerns the gene ERBB2 and breast cancer.