IntroductionRecent randomized trials have compared the efficacy and safety of stereotactic body radiation therapy (SBRT) with standard conventional external beam radiotherapy (cEBRT) for the treatment of painful spinal metastases. We conducted a composite analysis of these trials in order to inform current practice using pooled outcomes. MethodsData from each randomized trial were abstracted from the final publications with biologically effective doses (BEDs) recalculated for SBRT and cEBRT. Primary outcome measures were overall (OR) and complete pain response (CR) rates at 1, 3, and 6-months, and rates of vertebral compression fracture (VCF). Random effects models were used to estimate primary outcome measures and meta-regression assessed the effect of BED. ResultsFour prospective randomized clinical trials published between 2018 and 2024 were included, with a total of 686 patients (383 and 303 in the SBRT and cEBRT groups, respectively). Dose and fraction (fx) number for the SBRT group ranged from 24 Gy/ 1 fx to 48.5 Gy/ 10 fx (median BED10 50 Gy), and for the cEBRT group from 8 Gy/ 1 fx to 30 Gy/ 10 fx (median BED10 28 Gy). The 1, 3, and 6-month OR rates for SBRT and cEBRT were similar: 53.6%, 52.4%, 58.8% vs. 48.4%, 47.9%, 43.8%, respectively (p>0.05). The 3-month CR rate was significantly higher for SBRT compared to cEBRT (31.9% vs. 14.8%, RR 2.26; 95% CI, 1.48-3.45, p<0.001), but not the 6-month rate (34.4% vs. 16.3% RR 1.83; 95% CI, 0.74-4.53, p=0.194). VCF rates were similar at 17.3% and 18.4% for SBRT and cEBRT, respectively. No significant dose-dependent effect was observed with increasing BED for any efficacy or safety outcomes. ConclusionsOR pain response rates are similar, but CR pain response rates appear higher with SBRT compared to cEBRT, yet no dose-dependent effects were identified despite approximately 1.8x BED dose with SBRT.
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