Metastasis formation after intravenous tumour cell injection in thrombocytopenic rats.

Induced thrombocytopenia has been found to decrease metastasis formation after intravenous tumour cell injection which emphasizes the importance of platelets in metastasis formation. Using a syngeneic 20-methylcholanthrene-induced fibrosarcoma in rats, the effect of platelet reduction was investigated in combination with trauma and infusion of dextran 1000. It was found that platelets were important for the increased formation of metastases after trauma but not for the increased formation of metastases after infusion of dextran 1000. Thus, trauma and dextran 1000 stimulate metastasis formation by different mechanisms. Possible explanations are discussed.