Inclusion Criteria:

- A histologic diagnosis of malignancy;

- At planned initiation of a new systemic chemotherapy regimen (including patients
starting on first chemotherapy or patients previously treated but starting on a new
regimen);

- A risk score for VTE ≥3 [assign score of 2 for very high risk sites of cancer
(stomach, pancreas), score of 1 for high risk site (lung, lymphoma, gynecologic,
bladder, testicular) and score of 0 for all other sites], hemoglobin <10 g/dL or
planned use of erythropoiesis stimulating agents, platelet count ≥350,000/mm3, total
leukocyte count > 11,000/mm3 or body mass index ≥ 35 kg/m2]. Any counts meeting
criteria drawn within 2 weeks prior to enrollment are considered acceptable.

- Age 18 years or older

- Provide written, informed consent.

Exclusion Criteria:

- Active bleeding or at high risk of serious bleeding complication in the opinion of
the investigator

- Diagnosis of primary brain tumor multiple myeloma, leukemia, or myelodysplastic
syndrome

- Planned stem cell transplant

- Life expectancy < 6 months

- Known allergy to heparin or LMWH

- Patient or caregiver incapable of daily self-injection

- Acute or chronic renal insufficiency with creatinine clearance < 30 mL/min

- History of heparin-induced thrombocytopenia

- Allergy to contrast agents

- Pregnancy

- Need for anticoagulant therapy

- Platelet count < 75,000/mm3