Circulating " Cancer Cells / Macrophage " HYbrid Cells in Patients With Sarcoma, Part 2

Pilot, prospective, monocentric study aimed at evaluating the rate of patients with circulating "cancer cell/macrophage" hybrid cells in the peripheral blood and the evolution of this rate over time. The study will be conducted on a population of patients with leiomyosarcoma and treated in the context of routine care. 20 patients will be included: * 10 patients with localized disease. * 10 patients with metastatic disease. For each included patient, blood samples will be collected during baseline visit and up to 24 months after inclusion.