Preoperative Stereotactic Body Radiotherapy for Metastatic Bone Disease With Impending Fracture: A Nonrandomized Clinical Trial

BACKGROUND: Surgical stabilization followed by postoperative radiotherapy (RT) is the standard of care for impending pathologic fractures due to bone metastases. Compared with conventional RT, stereotactic body RT (SBRT) provides more durable tumor control and palliation, but treatment volume constraints often preclude postoperative use. Preoperative SBRT limited to the tumor volume offers a solution by delivering an ablative dose before intraoperative tumor dissemination, but its safety is not established. METHODS: We conducted a phase I, nonrandomized clinical trial at a quaternary care cancer center, with accrual between June 2021 and April 2024. Eligible patients (N=38) had pelvic or long bone metastases with impending pathologic fractures requiring surgical stabilization. Patients received preoperative SBRT (27-30 Gy in 3 fractions or 18-24 Gy in 1 fraction) followed by surgical stabilization within 1 week. The primary endpoint was rate of wound complications within 6 weeks after preoperative SBRT and surgical stabilization. Secondary endpoints were rates of tumor recurrence and grade ≥3 treatment-related toxicities within 1 year. RESULTS: A total of 7 patients were excluded due to inability to receive treatment or death prior to the primary endpoint. Thirty-one patients were evaluated at 6 weeks postoperatively, 26 at 3 months, and 16 at 1 year. The median age was 66 years (IQR, 59-71), and 15 (48%) patients were male. At 6 weeks, 2 of 31 patients (6.5%; 95% CI, 0.79-21.4) experienced wound complications. At 3 months, 1 of 26 patients (3.8%; 95% CI, 0.10-19.6) experienced grade ≥3 treatment-related toxicity. At 12 months, 1 of 16 patients (6.3%; 95% CI, 0.16-30.2) had tumor recurrence. CONCLUSIONS: Preoperative SBRT is associated with a low risk of wound complications and durable local tumor control. A randomized controlled trial examining its efficacy, potential to facilitate less invasive surgery, and impact on functional outcomes is warranted. CLINICALTRIALS: gov identifier: NCT05038124.