Definitive Stereotactic Body Radiotherapy for Unresectable Primary Bone and Soft Tissue Tumors: A Single-institution Experience.

AIMS: Definitive radiotherapy is a treatment option for unresectable bone and soft-tissue tumors (BSTTs). We aimed to evaluate the efficacy and safety of stereotactic body radiotherapy (SBRT) for primary BSTTs. MATERIALS AND METHODS: We retrospectively analyzed patients with unresectable primary BSTTs who underwent definitive SBRT. The prescribed dose was 50 Gy in five fractions, with a central dose of 80 Gy. The study endpoints were local failure (LF), progression-free survival (PFS), overall survival (OS), and treatment-related toxicity. RESULTS: A total of 26 patients underwent definitive SBRT. The median age was 72 years (range, 23-94 years), and seven patients (27%) had a performance status of 3-4. Most patients had advanced disease (stages III-IV, 85%), and surgery was not performed, primarily because of anatomical or functional unresectability (42%) or medical inoperability (35%). The median planning target volume was 439 cc (range, 42-2247). The median follow-up period was 12 months (range, 3-56 months). The 1-year cumulative incidence of LF was 8%, and the 1-year PFS and OS rates were 57% and 72%, respectively. Late grade 3 toxicities occurred in five patients (19%). CONCLUSION: SBRT achieved favorable local control in patients with unresectable BSTTs despite their poor general condition and advanced disease, suggesting that it represents a clinically meaningful definitive treatment option for patients with unresectable BSTTs for whom standard curative approaches are not feasible. However, careful monitoring for potentially severe late toxicities remains critical.