Efficacy and Safety of Stereotactic Body Radiation Therapy for Metastatic Bone Tumors in Clinical Practice

The development of radiation techniques has demonstrated that stereotactic body radiation therapy (SBRT) effectively achieves good local control and long-term pain palliation for metastatic bone tumors. This study evaluated the efficacy and safety of SBRT for metastatic bone tumors in clinical practice.

Fifty-five patients with 64 metastatic bone tumors treated at the University of Osaka Hospital from July 2014 to March 2022 were retrospectively analyzed. Local failure (LF) rates were estimated using competing risk analysis, and overall survival (OS) rates using the Kaplan-Meier method. Pain response rates were assessed as complete response, partial response, and pain progression based on the patient's chief complaint at three months, six months, and the last follow-up. Treatment response was determined using the Spine Response Assessment in Neuro-Oncology criteria.

The most common primary site was the prostate (n=18), and the spine was the most prevalent radiation site (n=45). Dose prescription was performed at a planning target volume of D_95%, with a median dose fraction of 35 Gy in five fractions. The median follow-up duration was 25.8 months (range=1.9-60.5 months), and the 2-year LF and OS rates were 3.4% and 72.4%, respectively. The pain response rate three months post-SBRT was 93.8%. Grade 2 and 3 toxicities occurred in 4.7% (three cases) and 1.6% (one case), respectively.

SBRT for metastatic bone tumors achieved low LF rates with low toxicity and favorable pain response and is an effective treatment option in clinical practice.