The Watchful Many: Platelets at the Intersection of Hemostasis, Immunity, and Cancer

Platelets are anucleate megakaryocyte-derived cytoplastic fragments best known for their roles in hemostasis and thrombosis, but they also play roles in systemic immune surveillance, vascular integrity, and tissue homeostasis. In cancer, this versatility is co-opted through communication between the tumor, bone marrow, and platelets. Tumor-derived cytokines, extracellular vesicles, and inflammatory cues can rewire thrombopoiesis and platelet activation, lifespan, and cargo, giving rise to tumor-educated platelets. Platelets support multiple stages of cancer progression by promoting metastatic traits in the tumor, cancer cell survival in the circulation, immune evasion, and vascular adhesion. Clinically, platelets are key drivers of coagulopathies in cancer patients, including venous and arterial thromboembolism, thrombotic microangiopathy, and disseminated intravascular coagulation. Here, we review platelet biology at the intersection of hemostasis, inflammation, and cancer.