Purpose: To describe the occurrence of radiation-induced soft tissue sarcomas in a retrospectively analyzed cohort of patients. To analyze the histologic subtypes and survival in this rare disease.
Patients and methods: While performing a retrospective analysis of soft tissue sarcomas in patients treated between 1974 and 1999 at the two major cancer centres in Alberta (Canada), eight patients presenting with nine sarcomas occurring in a previously radiated site were identified. Eight fulfilled the criteria for radiation-induced sarcoma.
Results: Radiation-induced sarcomas occurred between 10 months and more than 50 years after irradiation (median 7.35 years). Patients' ages ranged from 36 to 88 years (median 77.3 years) at the time of their sarcoma diagnosis. Histologically, four malignant fibrous histiocytomas, two dermatofibrosarcoma protuberans, two carcinosarcomas, and one fibrosarcoma were diagnosed. All patients received surgery as the primary treatment. Complete resection could not be achieved in three cases. Two of them died of disease. The 5-year disease-specific survival rate was 50%, whereas the 5-year overall survival rate was 25%.
Conclusions: Radiotherapy can induce malignancies after a latency period of a few months to several years. Radiation-induced sarcomas are associated with poor overall prognosis. The treatment in most cases is late and ineffective. The population at risk for the development of radiation-induced sarcoma is increasing, so vigilance is required in the follow-up of those patients.