OBJECTIVES:~To determine the influence of bevacizumab on platelet aggregation in patients receiving bevacizumab for cancer.~To determine the influence of VEGF on platelet aggregation.~To determine the influence of VEGF or bevacizumab on cyclooxygenesis.~To determine if the sequence of medication plays a role in platelet aggregation.~OUTLINE: Blood samples are collected before and after bevacizumab infusion. Samples are analyzed for measurements of platelet aggregation, coagulation parameters, and endothelial activation (e.g., fibrin fragment F1 and 2, thrombin and antithrombin complex, soluble P-selectin, Von Willebrand factor and factor VIII, tissue factor, and endothelin 1).
RATIONALE: Studying samples of blood from patients with cancer in the laboratory may help doctors learn more about the effect of bevacizumab and VEGF on platelet clustering.~PURPOSE: This research study is looking at the effect of bevacizumab and VEGF on platelet clustering in patients with cancer who are receiving bevacizumab.