CYP19A1 and uterine cancer: The 5-year incidence of endometrial cancer (defined as any uterine cancer except cervix cancer) was also low: seven (0·2%) of 3528 women in the aromatase inhibitor group versus 15 (0·3%) of 3502 in the tamoxifen group (p=0·14, figure 4, appendix p 18).