Treatment and outcome of radiation-induced soft-tissue sarcomas at a specialist institution.

BACKGROUND: Radiation-induced sarcoma (RIS) is a rare late complication of therapeutic irradiation with a reputation for aggressive pathology and poor outcome.
METHODS: We retrospectively reviewed histopathological features, surgery and outcome in 67 patients with RIS treated between 1990 and 2005 at a single tertiary referral center.
RESULTS: Previous breast cancer was the most common indication for radiotherapy. The median interval from irradiation to development of RIS of was 11 years (3-36 years). Median tumour size was 7 cm with 56% classified as high grade, 31% intermediate grade and 13% low grade. The commonest histology was leiomyosarcoma. The only relationship for histology with site was for angiosarcoma (n=9), all of which developed on the chest wall/breast after irradiation for breast cancer. Of 67 patients, 34 underwent potentially curative surgery, and microscopically clear margins were achieved in 75% of cases. Pedicled or free tissue transfer was required in 12 patients and abdominal or chest wall mesh reconstructions were required in 8 patients. No patient received adjuvant radiotherapy but 7 received adjuvant/neoadjuvant chemotherapy. Median follow up is 53 months. Median sarcoma specific survival was 54 months (2- & 5-year survival: 75% & 45%). The local relapse rate was 65%. Negative histopathological margins were a significant predictor of sarcoma specific survival (HR 3.0 95% CI 1.1-8.6 p=0.04). Grade and size of tumour approached, but did not attain significance.
CONCLUSION: RIS is a biologically aggressive tumour with high rates of local relapse despite aggressive attempts at curative surgery.