ABSTRACT
Women receiving chemotherapy for metastatic breast cancer are at high risk for thromboembolic disease, but long-term oral anticoagulation increases the risk of haemorrhagic complications. In this trial, 311 women receiving chemotherapy for metastatic breast cancer were randomly assigned to either low-dose warfarin (1 mg/daily for 6 weeks, adjusted upwards as required to maintain an international normalized ratio (INR) of 1.3-1.9) or placebo. Study treatment continued until 1 week after the end of chemotherapy. There were seven thromboembolic events (six deep-vein thromboses and one pulmonary embolism) in the placebo group and one (pulmonary embolism) in the warfarin group (a relative risk reduction of about 85%; p 0.031). Major bleeding occurred in two placebo recipients and one warfarin-treated patient. There was no detectable difference in survival between the treatment groups.
