Radiotherapy of chondrosarcoma of bone.

A retrospective analysis of 31 cases of chondrosarcoma of bone treated by radiotherapy at the Princess Margaret Hospital between 1958 and 1976 is presented. In comparison with other large series, our group of patients were found to have been unfavourably selected with respect to the known prognostic factors: histology (39% mesenchymal and dedifferentiated), site (75% arising in the trunk and head and neck), adequacy of operative treatment (none having had a complete surgical excision), and presenting symptoms (two-thirds presenting with pain). Twelve patients with primary (good, moderate, and unknown differentiation) chondrosarcoma were radically irradiated; 6 of these 12 have been alive and well without tumor for periods ranging from three and half to 16 years and 3 of these are alive and well for 15 years or more following radiotherapy. The other 6 patients responded or disease stabilized following radiotherapy for periods ranging from 16 months to eight years. One poorly differentiated tumor was radically irradiated and did not respond. Eleven patients were irradiated palliatively (5 dedifferentiated and mesenchymal, 4 secondary, and 2 primary chondrosarcomas), generally with low doses of irradiation, and only 4 responded transiently for periods ranging from three to 12 months. Seven patients with mesenchymal and dedifferentiated tumors were radically irradiated. Four responded or disease stabilized, and 1 of these patients was alive and well at 3 years; 3 did not respond. Six died with distant metastasis. It is concluded that chondrosarcoma of bone is a radioresponsive tumor and the place of radiotherapy in the treatment of this disease and the reason for its being labelled a radioresistant tumor are discussed. The problems of assessing response of chondrosarcoma to therapy are also discussed. It is suggested that chemotherapy may have a role in the management of mesenchymal and dedifferentiated chondrosarcoma.