Circulating " Cancer Cells / Macrophage " HYbrid Cells in Patients With Sarcoma?

Pilot, prospective, monocentric study aimed at evaluating the rate of patients with circulating "cancer cell/macrophage" hybrid cells in the peripheral blood. The study will be conducted on a population of patients with sarcoma and treated in the context of routine care. For each included patient, blood samples will be collected during baseline visit and after the initiation therapy. At the end of the 2nd blood collection, the patient will have completed his participation in the study.