Correlation of intraoperatively irradiated volume and fibrosis in patientswith soft-tissue sarcoma of the extremities

Purpose: To investigate the influence of intraoperatively irradiated volume on soft-tissue fibrosis. Methods and Materials: Fifty-three patients with soft-tissue sarcoma of the extremities were treated with intraoperative radiotherapy (IORT) (median d ose 15 Gy) and postoperative fractionated therapy (median dose 46 Gy). The median follow-up was 41.5 months (range 18-94). Late toxicity was classifie d according to the LENT-SOMA criteria. A Cox regression model was calculate d to identify the parameters that could influence soft-tissue fibrosis Grad e 3 or 4. Five parameters were observed: extent of surgical procedure, IORT in case of recurrence, extent of IORT volume, extent of IORT dose, and ext ent of postoperative volume. In addition, a logistic regression model was c alculated to demonstrate the relationship between the IORT volume and fibro sis development. Results: The overall survival rate after 5 years was 84%. The actuarial tum or control rate was 90% after 5 years. Ei-even patients developed soft-tiss ue fibrosis. Five patients developed Grade 3 fibrosis and 1 patient develop ed Grade 4 fibrosis. Only the IORT volume had a significant influence on Gr ade 3 or 4 fibrosis development. An IORT volume of 210 cm(3) conveyed a 5% risk (confidence interval 1-20%) of the development of severe fibrosis. The risk of severe Grade 3 or 4 fibrosis increased to 50% (confidence interval 15-80%) if a volume of 420 cm(3) was irradiated. Conclusion: The effect of volume in patients treated with IORT was remarkab le. The ratio of side effects was relatively low. The risk of soft-tissue G rade 3 or 4 fibrosis increased with the extent of the IORT volume. Compared with the literature, IORT provides excellent local control in these patien ts. (C) 2001 Elsevier Science Inc.