Superior venocaval obstruction secondary to central venous catheter-related thromboses in two patients with metastatic colorectal carcinoma receiving weekly 5-flurouracil. Should adjusted-dose warfarin be used as thromboprophylaxis?

Standard treatment for patients with metastatic colorectal carcinoma (MCC) involves treatment with weekly 5-flurouracil (5-FU) chemotherapy by continuous infusion, requiring the insertion of a central venous catheter (CVC). One of the main complications of CVCs is venous thromboembolic disease (VTE), with an incidence varying between 3 and 54% in different studies. During the past 14 months, 17 patients with MCC have been treated weekly with 5-FU in our unit, comprising 11 males and six females with a mean age of 60 years (range, 49-72 years). Thromboprophylaxis for all patients included 1 mg/day warfarin unless contraindicated. Three patients developed venography-confirmed CVC-related VTE, including two cases of occlusive superior venocaval VTE. All three patients were treated with intravenous thrombolytic drugs; two responded completely and one partially. We wonder whether the incidence of CVC-related VTE may be reduced further by using adjusted-dose warfarin rather than fixed low-dose warfarin. However, one has to be guarded because of the greater risk of bleeding with more intensive anticoagulation, especially in patients with liver metastases. Ongoing studies such as the warfarin prophylaxis study are essential to determine the safety and efficacy of different approaches in order to determine the optimum thromboprophylaxis for this group of patients.