Purpose:Tumor metastasis is the main cause of tumor death and poor long term effect in clinical treatment. In the process of metastasis, tumor cell adhesion is one of the key steps. It has been shown that P selectin and its ligands were related to tumor infiltration, invasion and the generation of metastastic lesions, and may be a prognostic factor or metastasis index. But the relationship between platelet P selectin and tumor emboli/metastasis need to be further investigated.