Immediate response to preoperative external beam radiotherapy in combined modality treatment of soft tissue sarcomas

The purpose of the study was to assess immediate response to preoperative external beam radiotherapy in patients with soft tissue sarcomas. The study comprised 55 patients with primary and recurrent soft tissue sarcomas. All patients underwent external beam radiotherapy at a total dose of 38-44 Gy in 5 fractions of 3 Gy daily, followed by surgery with 10-15 Gy intraoperative radiotherapy. The objective tumor response to preoperative external beam radiotherapy was assessed using RECIST criteria. Partial response to preoperative radiotherapy was achieved in 9.1% of patients and disease stabilization in 90.9% of cases. Grade I pathological tumor response was observed in 25 (46.5 %) patients, grade II tumor response in 19 (34.5 %) patients and grade III tumor response in 11 (20 %) cases. A 3-week interval between radiotherapy and surgery was the most optimal time. Pathological tumor response with RECIST criteria is an additional parameter in assessment of immediate tumor response.