Background: Tamoxifen is used for breast cancer treatment and has been reported to be beneficial for the cardiovascular system, but it is unclear whether tamoxifen exhibits a favorable cardiovascular effect in Asian patients. Methods and Results: From January, 1998 to December, 2006, a breast cancer cohort study was conducted using the Taiwan National Health Insurance database. Patients were divided according to whether tamoxifen was used. Study endpoints were occurrence of acute myocardial infarction (AMI), ischemic or hemorrhagic stroke and total cardiovascular events. A total of 3,690 female subjects were enrolled (mean age 50.1±11.3), 2,056 of whom received tamoxifen and 1,634 did not. During a mean follow-up of 6.9 years, the tamoxifen group had a significantly lower incidence of AMI (0.15% vs. 0.67%, P=0.008), ischemic stroke (1.99% vs. 3.30%, P=0.008), hemorrhagic stroke (0.15% vs. 0.55%, P=0.029), and total cardiovascular events (2.24% vs. 4.16%, P<0.001) than the non-exposed group. After adjusting for comorbidities, tamoxifen was independently associated with a reduced risk of myocardial infarction (hazard ratio [HR] 0.22; 95% confidence interval [CI] 0.07-0.70, ischemic stroke (HR 0.52; 95% CI 0.35-0.78), hemorrhagic stroke (HR 0.25; 95% CI 0.07-0.92), and total cardiovascular events (HR 0.54; 95% CI 0.37-0.78). Conclusions: In Asian female breast cancer patients, tamoxifen use was associated with reduced risks of AMI, ischemic, hemorrhagic stroke and total cardiovascular events.
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