A Study of Dalteparin Prophylaxis in High-Risk Ambulatory Cancer Patients

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