Factor v leiden mutation and thromboembolism risk in women receiving adjuvant tamoxifen for breast cancer

Abstract

Background Tamoxifen use has been associated with increased risk of thromboembolic events (TEs) in women with breast cancer and women at high risk for the disease. Factor V Leiden (FVL) is the most common inherited clotting factor mutation and also confers increased thrombosis risk. We investigated whether FVL was associated with TE risk in women with early-stage breast cancer who took adjuvant tamoxifen. Methods A case-control study was conducted among 34 Cancer and Leukemia Group B (CALGB) institutions. We matched each of 124 women who had experienced a docUmeånted TE while taking adjuvant tamoxifen for breast cancer (but who were not necessarily on a CALGB treatment trial) to two control subjects (women who took adjuvant tamoxifen but did not experience TE) by age at diagnosis (±5 years). DNA from blood was analyzed for FVL mutations. Conditional logistic regression was used to estimate odds ratios (ORs) and to evaluate other potential factors associated with TE and tamoxifen use. All P values are based on two-sided tests. Results FVL mutations were identified in 23 (18.5%) case and 12 (4.8%) control subjects (OR = 4.66, 95% confidence interval = 2.14 to 10.14, P