DEDIFFERENTIATED CHONDROSARCOMA: RETROSPECTIVE ANALYSIS OF 15 CASES. NATURAL HISTORY AND THERAPEUTIC STRATEGY

Purpose: This retrospective analysis was based on observations in 15 patients, seven men and eight women, mean age 48 years (19–72) treated between 1988 and 2000 at the Curie Institute. The tumour was located in limbs in eight patients (one humerus, two femurs, four tibias, one fibula), in the axial skeleton in five (four pelvi, one sacrum), and in the rib cage and the scapula in one each. Histology examination of the dedifferentiated component displayed fibrosacroma in six cases, HFM in two, rhabdomyosarcoma in two and leiomyosarcoma and osteosarcoma in one each. Six patients were given neoadjuvant and adjuvant chemotherapy of the osteosarcoma type and underwent conservative surgery of the affected limb in three out of four cases. Total histological necrosis was observed in three out of six cases. Six patients were given adjuvant treatment alone using an osteosarcoma protocol. Three unoperable patients were given palliative chemotherapy and radiotherapy. Results: Nine patients died from their disease. The most frequent metastatic site was the lung; mean survival was 20 months. Six patients survived including five with no progression (1+, 5+, 6+, 7+, 12+ years). Three out of five had had preoperative chemotherapy with a complete histological response and two out of five had had osteosarcoma protocol adjuvant chemotherapy. Conclusion: Dedifferentiated chondrosarcoma is generally considered to have very poor prognosis and should lead to an adapted therapeutic strategy. In our series, the osteosarcoma protocol provided complete histological response in three out of six patients. Five patients had prolonged survival, all had been given an osteosarcoma type chemotherapy protocol.