Efficacy and safety of enoxaparin versus unfractionated heparin for prevention of deep vein thrombosis in elective cancer surgery: A double-blind randomized multicentre trial with venographic assessment

BACKGROUND: Surgery for malignant disease carries a high risk of deep vein thrombosis. The aim of this study was to evaluate the prophylactic effect of a low molecular weight heparin, enoxaparin, 40 mg once daily, beginning 2 h before surgery, compared with that of unfractionated low-dose heparin three times daily. METHODS: Patients included were over 40 years of age and undergoing planned elective curative abdominal or pelvic surgery for cancer. The study was designed as a prospective double-blind randomized multicentre trial with participating departments from ten countries. Primary outcome was venous thromboembolism as detected by mandatory bilateral venography or pulmonary scintigraphy. Follow-up was at 3 months. RESULTS: Some 1115 patients were randomized into the study but venograms were inadequate in 460 (41.3 per cent). Of 631 evaluable patients, a total of 104 (16.5 per cent) developed thromboembolic complications. The frequency was 18.2 per cent in the heparin group and 14.7 per cent in the enoxaparin group (95 per cent confidence interval of the difference -9.2-2.3 per cent). There were no differences in bleeding events or other complications. One patient in the heparin group developed severe thrombocytopenia. There were no differences in mortality at either 30 days or 3 months. CONCLUSION: Enoxaparin, 40 mg once daily, is as safe and effective as unfractionated heparin three times daily in preventing venous thromboembolism in patients undergoing major elective surgery for abdominal or pelvic malignancy.