RESUMO
Objective:To investigate the effectiveness of postoperative radiotherapy using shrinking field for patients with extremity soft tissue sarcoma (STS), mainly focusing on the local control rate and adverse events.Methods:Clinical data of 49 extremity STS patients who received postoperative intensity-modulated radiotherapy in the First Hospital of Tsinghua University from October 2017 to March 2021 were retrospectively analyzed. Target volumes were contoured on CT and MRI fusion images. The tumor bed was defined as GTV tb, with 3 cm expansion in the longitudinal direction and 1.5 cm expansion in the radial direction to construct CTV (the target volume should be properly repaired according to the anatomical barrier, and the edema area around the tumor should be included). GTV tb and CTV were expanded in all directions by 0.5 cm to construct PTV1 and PTV2 respectively, at a dose of 95%PTV1 63-66 Gy, 95%PTV2 50-56 Gy,1.8-2.0 Gy/f. The dose of surgical volume should be given at 70 Gy for patients who had a microscopic positive margin. Results:The median follow-up time was 32.1 months (7.9-45.6 months). The 3-year local failure-free survival (LFFS), overall survival (OS)and distant metastasis-free survival (DMFS) were 91.7%,77.6% and 71.5%, respectively. Univariate analysis showed that patients with a microscopic positive margin were more likely to develop local recurrence ( P<0.05). The incidence of grade 2 or above wound complications, joint stiffness, fracture, edema and skin fibrosis were 2%, 4.1%, 2%, 8.2% and 26.5%, respectively. Conclusion:Postoperative radiotherapy with shrinking field provides excellent local control rate and low incidence of late adverse events in patients with extremity STS.