Alterations in platelet surface sialytransferase activity and platelet aggregation in a group of cancer patients with a high incidence of thrombosis.

Platelet aggregation, platelet surface sialic acid, and platelet surface sialytransferase activity were studied in a group of 12 cancer patients with a high incidence of thrombosis. These patients demonstrated accelerated coagulation, increased Factor VIII antigen and restocetin cofactor, and enhanced adenosine 5'-diphosphate-induced platelet aggregation. Platelet exogenous sialytransferase activity was increased in cancer patients (117.6 +/- 14 pmol/10(9) platelets) as compared to controls (59.0 +/- 4.3 pmol/10(9) platelets, p less than 0.01). Platelet exogenous sialytransferase activity and platelet aggregation were inhibited by aspirin. Thrombosis and bleeding have complicated the clinical course of half of these patients. This platelet membrane analysis provides additional data which may be related to current observations of increased levels of plasma sialytransferase activity and serum sialic acid in cancer patients.