Small but mighty: Platelets as multifunctional architects of tumor metastasis and immune regulation

Abstract Platelets play an irreplaceable role in hemostasis and wound healing. However, beyond these classical roles, as the smallest anucleate cells in the blood stream, they are crucial for immune response which have inflammatory functions through specialized receptors and different signaling pathways, influencing both innate and adaptive immune response. Furthermore, many research have proved that platelets significantly contribute to tumor metastasis and are associated with poor prognoses in cancer patients through its coagulability and supporting an immunosuppressive tumor microenvironment. When tumor cells detach from the primary tumor mass and enter the bloodstream, they rapidly initiate the direct activation and adhesion of platelets, forming a protective microenvironment. This environment shields circulating tumor cells (CTCs) from the mechanical shear forces of blood flow and immune surveillance. Here we delve into the interaction between platelets and immunomodulation and explore the multifaceted roles and underlying mechanisms by which platelets influence tumor cell metastasis and tumor growth. Furthermore, we also discussed the diagnostic role of platelets in cancer occurrence and progression, as well as the feasibility and prospects of targeting platelets for antitumor immunotherapy. This review provides a multidimensional perspective and reference for platelet‐related cancer treatment strategies and diagnosis.