Warfarin and cancer

New York, June 30, 2000 (Praxis Press) - The incidence of cancer increases after the diagnosis of venous thromboembolism, which is usually treated with vitamin K antagonists such as warfarin. Few randomized trials have examined the relation between the development of metastases and the clotting mechanism. During a prospective, randomized study that lasted eight years, Schulman and Lindmarker have compared the effects on the incidence of cancer of a six-week and a six-month warfarin treatment given to patients after a first episode of venous thromboembolism (see paper). The study shows that while the incidence of cancers is higher during the first two years -- overall ratio of 3.4 -- it is lower in the patients who received the six-month warfarin treatment, 10.3 percent vs. 15.8 percent. The study strongly suggests that warfarin has an antineoplastic effect, although its mechanism is still unknown. While such data are too scarce to justify ...