Does surgery for metastatic spinal tumors improve functional outcomes in patients without spinal cord compression but with potentially unstable spines (SINS 7-12)?

Abstract

In the absence of spinal cord compression, it is unclear if surgery is more effective than radiation treatment for improving functional outcomes in metastatic spinal tumor patients with potentially unstable spines. The authors compared functional status outcomes assessed with Karnofsky Performance Status (KPS) and Eastern Cooperative Oncology Group (ECOG) scores after surgery or radiation in patients without spinal cord compression with Spine Instability Neoplastic Score (SINS) values of 7-12 indicating possible instability (SINS 7-12). A retrospective review was performed of patients with metastatic spinal tumor SINS values of 7-12 at a single institution between 2004 and 2014. Patients were divided into two different groups: 1) those treated with surgery and 2) those treated with radiation. Baseline clinical characteristics were measured, and KPS and ECOG scores were obtained pre- and postradiation or postsurgery. The paired, nonparametric Wilcoxon signed-rank test and ordinal logistic regression analysis were used for statistical analysis. A total of 162 patients met inclusion criteria; 63 patients were treated operatively and 99 patients were treated with radiation. The mean follow-up was 1.9 years, with a median of 1.1 years for the surgical cohort (ranging from 2.5 months to 13.8 years) and a mean of 2 years with a median of 0.8 years for the radiation cohort (ranging from 2 months to 9.3 years). After covariates were accounted for, the average posttreatment changes in KPS scores in the surgical cohort were 7.46 ± 17.3 and in the radiation cohort were -2 ± 13.6 (p = 0.045). No significant difference was observed in ECOG scores. KPS scores improved postoperatively in 60.3% of patients in the surgical group and postradiation in 32.3% of patients in the radiation cohort (p < 0.001). Subanalysis within the radiation cohort revealed no differences in fracture rates or local control between patients treated with external-beam radiation therapy versus stereotactic body radiation therapy. In patients initially treated with radiation, 21.2% eventually developed compression fractures at a treated level. Five of the 99 patients in the radiation cohort-all of whom had a fracture-eventually underwent either methyl methacrylate augmentation or instrumented fusion. Patients with SINS values of 7-12 who underwent surgery had greater improvement in KPS scores-but not in ECOG scores-than patients undergoing radiation alone. In patients treated with radiation, treatment was converted to a procedural intervention such as surgery only in patients who sustained fractures. Of the patients with fractures after radiation (21 of 99), 5 patients underwent an invasive procedure and 16 did not.