CD63 and cancer: Elevated circulating levels of platelet activation-related markers, such as platelet-specific α-granuloprotein, CD62, CD63, and P-selectin, have been observed in cancer patients [34,42], particularly in the advanced stages of various cancers, such as prostate, breast, and gastric cancers, where levels of β-thromboglobulin (β-TG) are also significantly elevated [43,44].