Platelets and the hallmarks of cancer. The original hallmarks of cancer included 6 biologic capabilities acquired during the complex development of tumors. Highlighted and discussed in the text are circulating platelet properties that contribute to some of the hallmarks. Thus, the platelet can be viewed as a normal cell contributing to the hallmark traits and influencing the TME. Antiplatelet therapies in the realm of cancer development and progression represent a future direction likely to impact patient prognosis and outcome.