Because the trials included only premenopausal women, few non-breast cancer deaths occurred: 30 (0·9%) of 3528 women in the aromatase inhibitor group versus 24 (0·7%) of 3502 women in the tamoxifen group died without breast cancer recurrence (RR 1·30, 95% CI 0·75–2·25; p=0·34; figure 4, appendix p 16). This evidence concerns the gene CYP19A1 and breast cancer.