Meta-Analysis of STereotactic body radiothERapy in non-spine BONE metastaseS (MASTER-BONES).

Purpose The efficacy and safety of stereotactic body radiation (SBRT) for patients with non-spine bone metastases (NSBM) remains in question. A systematic review and meta-analysis was performed to evaluate SBRT treatment outcomes in NSBM. Methods and Materials Eligible studies were retrieved from Medline, Embase, Scielo, the Cochrane Library, and annual meeting proceedings until July 6, 2023. We adhered to the PRISMA and MOOSE guideline recommendations. Quantitative synthesis was performed using a random effects model. Results Seven retrospective studies, with a total of 807 patients (1048 lesions) treated with stereotactic body radiation were included, with median follow-up ranging from 7.6-26.5 months. The most common stereotactic body radiation sites were pelvis (39.2%), ribs (25.8%), femur (16.7%), and humerus/shoulder region (8.7%). At 1-year, the LF and FR were 7% (95%CI 5.5-8.5%; I2=0, n= 75/1048), and 5.3% (95%CI 3-7.5%;I2=0, n= 65/1010). The 2-year cumulative LF incidence was 12.1% (95% CI: 10-15.5%). The OS and PFS at 1-year were 82% (95%CI 75-88%;I2=82%, n= 746/867), and 33.5%(95%CI 26-41%;I2=0%, n= 51/152), with a median of 20.2 months (95%CI: 10.9–49.1 months) and 8.3 months (95% CI: 6.3-10.3%) for OS and PFS, respectively. Meta-regression analysis revealed a significant relationship between planning target volume and fracture rate (p<0.05). Ribs 2.5% followed by the femur 1.9% (95%CI:0-6.1%) were the most common fracture sites. The occurrence of pain flare, fatigue and dermatitis were 7 %, 5.4 %, and 0.65 %, respectively. Conclusions Stereotactic body radiation proves both safety and efficacy for non-spine bone metastases and serious complications (grade 3) are infrequent. Careful consideration of target volume is crucial due to its link with a higher fracture risk.