**5.1 Aspirin**

Platelets activation is a part of coagulation process and venous thrombosis. Aspirin is an inhibitor of platelet-derived cyclooxygenaze1 (COX1) and thromboxane A and is the most common used antiplatelet agents through the world. Studies showed that aspirin can decrease thrombotic events in older patients with cancer without evidence of increased major bleeding [27, 28].
