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

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.

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.

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%).

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.