The overall incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) is 1 per 200 cancer patients, about 5 times higher than in the general population.~These events are of crucial importance, since nearly 10% of cancer patients died from thromboembolic events (EVT), making them the second leading cause of death in this population.~In hospitalized patients, the rate seems to have increase between 1979 and 1990 from 0.6% - 2% before 1990 to 4% since 1990.~Some studies report an increase in the hospitalization cost of 38%, correlated in part with the increase in hospitalization duration related to venous thromboembolism.~Thrombotic risk in cancer patients is known and identified. Thrombotic complications affect the survival and quality of life of cancer patients. Scores were established and validated to establish this risk and to propose prophylaxis in these patients. Guidelines exist for prophylaxis and for the treatment of these patients.~Chemotherapy is a regular generator of cytopenia, the most prominent of which is thrombocytopenia. In addition, a prospective study of 107 cancer patients in our institution shows that almost 40% of patients over 65 years of age take anticoagulant or antiplatelet therapy.~In this specific population (i.e., with cancer and hypocoagulability), the occurrence of thrombosis poses particular problems. The prevalence and incidence of venous thrombosis in this situation is unknown and the behavior to be poorly specified.~Based on these considerations, The investigator propose a two-year prospective cohort study to explore the biological parameters of hypocoagulability and to assess the incidence and prevalence of DVT in thrombocytopenic patients on vitamin K antagonists. (AVK), anti-platelet aggregation (AGP) and / or direct oral anticoagulant (AOD).~In this study, the investigator means by hypocoagulability any situation modifying the normal coagulation system, that is to say:~The presence of any anti-coagulant or antiplatelet treatment,~Or abnormalities of primary or secondary hemostasis causing coagulation disorders.~Some studies report an increase in the hospitalization cost of 38%, correlated in part with the increase in hospitalization duration related to venous thromboembolism.~Thrombotic risk in cancer patients is known and identified. Thrombotic complications affect the survival and quality of life of cancer patients. Scores were established and validated to establish this risk and to propose prophylaxis in these patients. Guidelines exist for prophylaxis and for the treatment of these patients.~Chemotherapy is a regular generator of cytopenia, the most prominent of which is thrombocytopenia. In addition, a prospective study of 107 cancer patients in our institution shows that almost 40% of patients over 65 years of age take anticoagulant or antiplatelet therapy.~In this specific population (i.e., with cancer and hypocoagulability), the occurrence of thrombosis poses particular problems. The prevalence and incidence of venous thrombosis in this situation is unknown and the behavior to be poorly specified.~Based on these considerations, The investigator propose a two-year prospective cohort study to explore the biological parameters of hypocoagulability and to assess the incidence and prevalence of DVT in thrombocytopenic patients on vitamin K antagonists (AVK), anti platelet aggregation (AGP) and / or direct oral anticoagulant (AOD).~In this study the investigator mean by hypocoagulability any situation modifying the normal coagulation system, that is to say:~the presence of any anti-coagulant or antiplatelet treatment,~or abnormalities of primary or secondary hemostasis causing coagulation disorders.
The overall incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) is 1 per 200 cancer patients, about 5 times higher than in the general population.~These events are of crucial importance, since nearly 10% of cancer patients died from thromboembolic events (EVT), making them the second leading cause of death in this population.~In hospitalized patients, the rate seems to have increase between 1979 and 1990 from 0.6% - 2% before 1990 to 4% since 1990.~Thrombotic risk in cancer patients is known and identified. Thrombotic complications affect the survival and quality of life of cancer patients.~Chemotherapy is a regular generator of cytopenia, the most prominent of which is thrombocytopenia. In addition, a prospective study of 107 cancer patients in our institution shows that almost 40% of patients over 65 years of age take anticoagulant or antiplatelet therapy.~In this specific population (i.e., with cancer and hypocoagulability), the occurrence of thrombosis poses particular problems. The prevalence and incidence of venous thrombosis in this situation is unknown and the behavior to be poorly specified.~Based on these considerations, The investigator propose a two-year prospective cohort study to explore the biological parameters of hypocoagulability and to assess the incidence and prevalence of DVT in thrombocytopenic patients on vitamin K antagonists. (AVK), anti-platelet aggregation (AGP) and / or direct oral anticoagulant (AOD).~In this study, the investigator means by hypocoagulability any situation modifying the normal coagulation system.