ABSTRACT
Oral anticoagulant therapy can be difficult in patients with cancer. Frequent blood sampling may be necessary because diet, medication, gastrointestinal absorption, and hepatic function alter the anticoagulant dose response. This is particularly inconvenient because these patients often have limited venous access. Due to the delayed onset and reversal of action, oral anticoagulants must be discontinued days before an invasive procedure, and therapeutic levels may not be reached again for days after reversal of the anticoagulant effect. Such interruptions in anticoagulation make dose adjustment more difficult. Due to the narrow therapeutic window of vitamin K antagonists, unpredictable fluctuations in the INR may lead to excessive bleeding or recurrent thrombosis.
