In 2004, a case control study with 1,442 cases and 1,420 controls reported a reduction in risk of breast cancer with aspirin use among those women with hormone receptor positive tumours (OR = 0.74, 95% CI = 0.60) but not for women with hormone receptor negative tumours (OR = 0.97, 95% CI = 0.67–1.40) [12]. This evidence concerns the gene NR4A1 and breast cancer.