Three of the five observational studies that compared tamoxifen use with non-tamoxifen use suggested a decreased risk of stroke in tamoxifen users.21, 24, 26, 43 Furthermore, the results for angina were consistent with patterns seen for myocardial infarction, but only four studies explored this outcome.19, 28, 41, 42, 43 However, one randomised controlled trial reported an increased risk of angina in aromatase inhibitor users compared with placebo users (relative risk 1.35, 95% confidence interval 1.17 to 1.56). This evidence concerns the gene CYP19A1 and Stroke.