Local Tumor Control for Metastatic Epidural Spinal Cord Compression Following Separation Surgery with Adjuvant CyberKnife Stereotactic Radiotherapy or Image-Guided Intensity-Modulated Radiotherapy

BACKGROUND: We sought to compare local tumor control after conventionally fractionated image-guided intensity-modulated radiotherapy (IMRT) versus adjuvant CyberKnife stereotactic body radiotherapy (SBRT) in patients who underwent separation surgery for metastatic epidural spinal cord compression (MESCC). METHODS: We retrospectively reviewed patients with MESCC who were treated at our hospital. The Kaplan-Meier method was used to estimate local progression and overall survival. RESULTS: Fifty-six patients with MESCC underwent separation surgery between 2013 and 2018, among whom 6 were lost to follow-up, 24 received conventionally fractionated image-guided IMRT, and 26 were treated with CyberKnife SBRT. The median follow-up was 16.5 months (range, 2.1-47.5 months). Eleven patients experienced local failure including 9 and 2 from the IMRT and SBRT groups, respectively. The local progression-free survival rates were significantly higher in the SBRT group than IMRT group at 6 months (95.5% vs. 82.0%), 1 year (90.9% vs. 71.8%), and 2 years (90.9% vs. 57.6%) (P = 0.035). Multivariate Cox proportional hazards regression analysis identified radiotherapy method (P = 0.034) and receipt of preoperative radiotherapy (P = 0.047) as significant predictors of local control, while visceral metastasis (P = 0.048) and high-malignancy primary tumor type (P = 0.002) were negative predictors of overall survival. Moreover, postoperative SBRT was noninferior to IMRT in terms of pain control, adverse effects, and performance in treating irradiated spinal metastases. CONCLUSIONS: Hybrid surgery-radiosurgery therapy is a safe and effective treatment option for patients with MESCC. SBRT provided higher local control rates compared with IMRT. Thus postoperative SBRT should be considered for patients expected to have relatively long survival.