Chondrosarcomas: Multidisciplinary review and practical recommendations, on behalf of GroupOs.

Chondrosarcomas are rare tumors occurring in middle age and older adults, defined by malignant cartilaginous matrix-producing neoplasms. Chondrosarcomas represent a heterogeneous group of tumors with diverse characteristics, management strategies and prognosis. The aim is to establish recommendations to support optimal practice for the diagnosis and treatment of chondrosarcomas within the framework of an expert group at the request of GroupOs and the French Sarcoma Group. The recommendations were developed by a multidisciplinary working and underwent thorough proofreading. The level of evidence in scientific literature and the grading of recommendations by the French Haute Autorité de santé (HAS) were taken into account. Key recommendations cover: (i) diagnosis, management and follow-up enchondromatosis; (ii) initial assessment, diagnosis and staging of cartilaginous tumor; (iii) management of low-grade, clear cell and high-grade, localized resectable chondrosarcomas; (iv) indications for radiotherapy in chondrosarcomas; (v) management of locally advanced and metastatic disease; (vi) management of mesenchymal chondrosarcomas. Surgical resection at a specialized center remains the mainstay for localized chondrosarcomas management, tailored to grade and anatomical location. Limited evidence supports the use of neoadjuvant or adjuvant treatment in chondrosarcomas, except in mesenchymal chondrosarcomas. For patients with dedifferentiated chondrosarcomas, neo or adjuvant treatment with osteosarcoma-like regimens may be proposed. In cases of recurrence or metastasis, local treatment should be prioritized or participation in clinical trials including new targeted or immune therapies should be considered. This article presents consensus recommandations from adult and pediatric sarcoma experts of various disciplines on the practical management of chondrosarcomas patients.