PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Not specified Life expectancy: Greater than 6 months Hematopoietic: Hemoglobin greater than 8.5 g/dL Platelet count greater than 100,000/mm3 No history of heparin and/or low weight molecular heparin induced thrombocytopenia No history of bleeding diathesis Hepatic: No history of coagulation factor deficiency No hepatic encephalopathy No hepatic failure No cirrhosis No hemophilia Renal: Creatinine less than 2.5 mg/dL (no greater than upper limit of normal for diabetes mellitus) Cardiovascular: No New York Heart Association class III or IV heart disease No congestive heart failure No uncontrolled hypertension (i.e., systolic blood pressure at least 180 mmHg and diastolic blood pressure at least 110 mmHg) No endocarditis No hemorrhagic stroke No prior or concurrent deep vein thrombosis Pulmonary: No prior or concurrent pulmonary embolus Other: No known allergy to enoxaparin or standard heparin No known allergy to fish (e.g., protamine sulfate) or swine products No active ulcerative disease or angiodysplasia of the gastrointestinal (GI) tract or active GI bleeding within the past 6 months No other active significant medical illness or major failure of any organ system No refusal of donor blood products secondary to religious or other reasons Not pregnant or nursing