Thrombogenic activity of mouse and human tumors: effects on platelets, coagulation, and fibrinolysis, and possible significance for metastases.

Twelve mouse tumors and 29 human malignancies were assayed in vitro for their capacity to aggregate platelets and induce release of radiolabelled serotonin, and for their ability to coagulate blood plasma and digest the fibrin clot. It was discovered that many human and mouse tumors can induce release of radiolabelled serotonin but that the quantitative relationships between this activity of tumors and their capacity to aggregate platelets was variable, permitting tumors to be classified into 3 different types. The procoagulant and fibrinolytic activity was also quite variable. Since no correlation was found between the 4 assayed tumor activities they appear to be independent, separate thrombogenic properties of tumors. Although the information gathered by this study is still fragmentary, some speculations can be made about the role of these activities in treatment of malignant tumors and in determing patterns of body distribution and control of metastases.