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...