Dalteparin Low Molecular Weight Heparin for Primary Prophylaxis of Venous Thromboembolism in Brain Tumour Patients

Inclusion Criteria: * Both of the following criteria must be satisfied: 1. Patients with newly-diagnosed pathologically-confirmed WHO Grade 3 or Grade 4 glioma (anaplastic astrocytoma, glioblastoma multiforme, gliosarcoma, anaplastic oligodendroglioma, and anaplastic mixed glioma). Tumour histology is based on local pathology review only; 2. Patients 18 years of age or older at time of randomization Exclusion Criteria: * If one or more of the following criteria are satisfied, the patient is not eligible for the study: 1. The presence of acute or chronic DVT demonstrated by duplex ultrasonography (DUS) or venography. (Note: a screening DUS is not required for study entry); 2. Inability to commence study drug within four weeks of original surgery or biopsy; 3. Serious hemorrhage requiring hospitalization, transfusion, or surgical intervention within four weeks of potential study entry; 4. Presence of a coagulopathy (e.g. INR \>1.5 or platelet count \< 100x109/L); 5. Symptomatic intracranial or intratumoural bleeding. (Note: post-operative imaging of the brain is not required for study entry. Asymptomatic "routine" post-operative blood products in a post-surgical cavity are not an exclusion; 6. Known acute (symptomatic or actively bleeding) gastroduodenal ulcer; 7. Familial bleeding diathesis; 8. Requiring long term anticoagulants for other reasons (e.g., mechanical heart valves, atrial fibrillation); 9. Uncontrolled hypertension despite antihypertensive therapy; 10. Significant renal failure (dependent on dialysis or creatinine of greater than three times upper limit of normal control); 11. Prior history of documented DVT or PE; 12. Allergy to anticoagulants (UFH, LMWH) including immune-mediated heparin-induced thrombocytopenia; 13. Pregnant or of childbearing potential and not using adequate contraception; 14. Geographically inaccessible for follow-up; 15. Having an expected life span of less than 6 months; 16. Body weight \< 40 kg.