Efficacy and safety analysis of intraoperative radiotherapy for soft tissue sarcoma: The largest-sample, single-center, real-world data review.

Abstract

11579 Background: This study aimed to evaluate the efficacy and safety of surgery combined with intraoperative radiotherapy (IORT) versus surgery combined with postoperative adjuvant radiotherapy in the treatment of soft tissue sarcoma (STS). It sought to identify patient subgroups that derive the most benefit from IORT and to provide evidence for treatment selection. Methods: This retrospective single-center study was conducted at Tianjin Medical University Cancer Institute & Hospital between May 2021 and December 2024. A total of 420 patients with pathologically confirmed STS were initially screened. After applying strict inclusion and exclusion criteria, 252 eligible patients were enrolled and divided into two groups: 147 patients who underwent surgery combined with IORT using the INTRABEAM 600 System, and 105 patients who received surgery combined with conventional postoperative adjuvant radiotherapy. Results: After a median follow-up period of 17.2 months (range: 4.8-47.18 months), the IORT group demonstrated significantly superior outcomes. Multivariate analysis identified three independent risk factors for RFS: radiotherapy modality (IORT vs. postoperative radiotherapy, p = 0.001), primary versus recurrent tumor status (p < 0.001), and T stage (p = 0.003). The RFS in the IORT group was significantly better than in the postoperative radiotherapy group (P = 0.001). Subgroup analysis revealed that IORT was particularly advantageous for specific patient populations. Tumor size was a critical determinant: for lesions larger than 5 cm in diameter, IORT significantly improved RFS across all subgroups ( > 15 cm: p = 0.008; 10-15 cm: p = 0.008; 5-10 cm: p = 0.004). However, for tumors smaller than 5 cm, no significant difference was observed between the two treatment modalities (p = 0.874). For OS, multivariate analysis identified radiotherapy type (p = 0.01) and AJCC stage (p = 0.007) as independent risk factors. The IORT group showed a trend toward improved OS, though longer follow-up is needed for definitive conclusions. The safety analysis strongly favored IORT. The incidence of treatment-related adverse events was significantly lower in the IORT group across all categories. Conclusions: This large-sample, single-center real-world study demonstrates that surgery combined with intraoperative radiotherapy significantly prolongs recurrence-free survival and improves local control in soft tissue sarcoma patients compared to surgery combined with postoperative radiotherapy. The benefits are most pronounced in patients with primary or recurrent tumors larger than 5 cm in diameter. Additionally, IORT offers a substantially more favorable safety profile with significantly reduced rates of radiation-related adverse events.