OBJECTIVES: I. Determine the patterns of tissue factor pathway inhibitor (TFPI) release according to tumor type and type of anticoagulation (heparin or enoxaparin) in patients with cancer. II. Determine the incidence of portacath clots and its correlation to TFPI releasability in this patient population. III. Compare these anticoagulation drugs in terms of releasability of TFPI in this patient population.