There was weak evidence that HER2 status might affect the benefit of aromatase inhibitor over tamoxifen for recurrence (p=0·021, figure 2): recurrence rates were similar with aromatase inhibitors and tamoxifen in women with HER2-positive tumours (16·0% vs 13·9%), although just 723 (15·7%) of 4594 women with ER-positive status had HER2-positive disease, and hence there were few events and a wide CI. This evidence concerns the gene CYP19A1 and neoplasm.