A Phase II Prospective Study of Preoperative Spatially Fractionated Radiation Therapy (SFRT) in Soft Tissue Sarcoma (neoSFRT-SARC)
The goal of this prospective, single-arm, phase II trial is to evaluate whether a preoperative regimen combining spatially fractionated radiation therapy (SFRT) with subsequent surgery can improve outcomes in patients with large (≥5 cm) limb/trunk soft tissue sarcoma (STS). Currently, there is a lack of standardized SFRT-based protocols for operable or borderline-resectable large STS, and optimal dose-fractionation schedules, timing to surgery, differential efficacy by resectability status, and the induced systemic immune response remain undefined. Patients will receive 5 fractions of SFRT to the primary tumor, followed by definitive surgery. The main questions are: * Can this SFRT-first approach increase the 1-year disease-free survival (DFS) compared with historical controls? * What are the pathologic complete response (pCR) rate, overall survival (OS), and treatment-related safety profile? * What immune mechanisms are engaged by SFRT, as reflected by dynamic changes in peripheral immune cell subsets and cytokines? Participants will undergo SFRT, then surgery, with serial blood sampling for immune monitoring.
• Histologically confirmed soft tissue sarcoma of the extremity or trunk, with tumor size ≥5 cm in greatest dimension (by imaging or clinical examination).
• Disease classified as operable or borderline-resectable as determined by the multidisciplinary tumor board.
• Age ≥18 years at the time of consent.
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2.
• Adequate organ function as defined by:
⁃ Absolute neutrophil count ≥1.5 × 10⁹/L; Platelet count ≥100 × 10⁹/L; Hemoglobin ≥9.0 g/dL; Total bilirubin ≤1.5 × upper limit of normal (ULN) (or ≤3 × ULN in patients with Gilbert's syndrome); AST/ALT ≤2.5 × ULN; Creatinine clearance ≥50 mL/min (by Cockcroft-Gault or measured);
• Women of childbearing potential must have a negative serum or urine pregnancy test within 7 days prior to enrollment and agree to use effective contraception during the study treatment period and for at least 3 months after the last study procedure. Men with partners of childbearing potential must agree to use effective contraception during the same period.
• Willing and able to provide written informed consent and comply with all study procedures, including scheduled follow-up visits and blood sample collections.