Extraskeletal osteosarcoma: analysis of outcome of a rare neoplasm.

Purpose. Extraskeletal osteosarcoma represents an unusual soft-tissue sarcoma that historically is reported to carry an exceptionally poor prognosis.The objectives of this study were to use a prospectively gathered sarcoma database to test the prevailing clinical bias and more accurately describe the natural history, characterize the prognostic features, estimate survival and evaluate treatment strategies for this unusual sarcoma.Patients and methods. From a large database of nearly 4000 sarcomas at a single institution, 15 patients with pathologically confirmed extraskeletal osteosarcoma were analysed.Results and discussion. Extraskeletal osteosarcoma usually occurs as a large, deep, high-grade lesion in the lower extremity of older patients. Overall and disease-specific survival at 5 years was 50%, with a median follow-up of 35 months (range 3- 200 months). Use of adjuvant chemotherapy or radiation therapy did not appear to influence survival, but an effect may have been missed by the relatively low numbers in each group.When matched to a comparable group of patients with stage III extremity sarcomas, there was no significant difference in overall or disease-specific survival between groups. Treatment for extraskeletal osteosarcoma should follow established guidelines for treatment of soft-tissue sarcomas, with the decision regarding adjuvant therapy to be based on individual risk factors.