Inclusion Criteria:

-Scheduled or to be scheduled for surgery performed on neoplasms of the pelvis or lower
limbs, including both primary musculoskeletal lesions as well as metastatic lesions; these
neoplasms may include major tumor resections, metastatic and pathologic fractures of the
hip and lower extremities (LE), open biopsies, and primary malignant tumors; an active
malignant neoplasm must be present at the time of surgery

Exclusion Criteria:

- Prior history of DVT or PE

- Previously placed vena cava filter

- No detectable malignant disease at the time of operation

- Previous arterial thrombosis (myocardial infarction [MI], cerebral vascular accident
[CVA])

- Severe platelet dysfunction (uremia, medications, dysplastic hematopoiesis); excluded
if platelets < 50,000

- Preoperative anticoagulation or active/serious bleeding in past 2 weeks (prothrombin
time [PT] & partial thromboplastin time [PTT] > 1.6 & > 35)

- Hypersensitivity or allergy to aspirin or heparin (including those diagnosed with
heparin-induced thrombocytopenia)

- Conditions associated with bleeding (active ulcer disease, recent neurosurgery,
bleeding disorders)

- Patients with renal insufficiency (creatinine [Cr] > 1.5)

- Pregnant patients

- Epidural anesthesia