Miller Jacob A, Balagamwala Ehsan H, Berriochoa Camille A, Angelov Lilyana, Suh John H, Benzel Edward C, Mohammadi Alireza M, Emch Todd, Magnelli Anthony, Godley Andrew, Qi Peng, Chao Samuel T
Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic.
Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic.
J Neurosurg Spine. 2017 Oct;27(4):436-443. doi: 10.3171/2017.3.SPINE161015. Epub 2017 Jul 21.
OBJECTIVE Spine stereotactic radiosurgery (SRS) is a safe and effective treatment for spinal metastases. However, it is unknown whether this highly conformal radiation technique is suitable at instrumented sites given the potential for microscopic disease seeding. The authors hypothesized that spinal decompression with instrumentation is not associated with increased local failure (LF) following SRS. METHODS A 2:1 propensity-matched retrospective cohort study of patients undergoing SRS for spinal metastasis was conducted. Patients with less than 1 month of radiographic follow-up were excluded. Each SRS treatment with spinal decompression and instrumentation was propensity matched to 2 controls without decompression or instrumentation on the basis of demographic, disease-related, dosimetric, and treatment-site characteristics. Standardized differences were used to assess for balance between matched cohorts. The primary outcome was the 12-month cumulative incidence of LF, with death as a competing risk. Lesions demonstrating any in-field progression were considered LFs. Secondary outcomes of interest were post-SRS pain flare, vertebral compression fracture, instrumentation failure, and any Grade ≥ 3 toxicity. Cumulative incidences analysis was used to estimate LF in each cohort, which were compared via Gray's test. Multivariate competing-risks regression was then used to adjust for prespecified covariates. RESULTS Of 650 candidates for the control group, 166 were propensity matched to 83 patients with instrumentation. Baseline characteristics were well balanced. The median prescription dose was 16 Gy in each cohort. The 12-month cumulative incidence of LF was not statistically significantly different between cohorts (22.8% [instrumentation] vs 15.8% [control], p = 0.25). After adjusting for the prespecified covariates in a multivariate competing-risks model, decompression with instrumentation did not contribute to a greater risk of LF (HR 1.21, 95% CI 0.74-1.98, p = 0.45). The incidences of post-SRS pain flare (11% vs 14%, p = 0.55), vertebral compression fracture (12% vs 22%, p = 0.04), and Grade ≥ 3 toxicity (1% vs 1%, p = 1.00) were not increased at instrumented sites. No instrumentation failures were observed. CONCLUSIONS In this propensity-matched analysis, LF and toxicity were similar among cohorts, suggesting that decompression with instrumentation does not significantly impact the efficacy or safety of spine SRS. Accordingly, spinal instrumentation may not be a contraindication to SRS. Future studies comparing SRS to conventional radiotherapy at instrumented sites in matched populations are warranted.
目的 脊柱立体定向放射外科治疗（SRS）是治疗脊柱转移瘤的一种安全有效的方法。然而，鉴于存在微小病灶播散的可能性，这种高度适形的放射技术在有内固定的部位是否适用尚不清楚。作者推测，内固定减压与SRS后局部失败（LF）增加无关。方法 对接受SRS治疗脊柱转移瘤的患者进行了一项2:1倾向评分匹配的回顾性队列研究。排除影像学随访时间少于1个月的患者。根据人口统计学、疾病相关、剂量学和治疗部位特征，将每例接受脊柱减压和内固定的SRS治疗与2例未进行减压或内固定的对照进行倾向评分匹配。使用标准化差异评估匹配队列之间的平衡性。主要结局是LF的12个月累积发生率，将死亡作为竞争风险。显示任何野内进展的病灶被视为LF。感兴趣的次要结局是SRS后疼痛加剧、椎体压缩骨折、内固定失败以及任何≥3级毒性反应。使用累积发生率分析估计每个队列中的LF，并通过Gray检验进行比较。然后使用多变量竞争风险回归对预先指定的协变量进行调整。结果 在650名对照组候选患者中，166名与83名接受内固定的患者进行了倾向评分匹配。基线特征平衡良好。每个队列的中位处方剂量为16 Gy。各队列之间LF的12个月累积发生率无统计学显著差异（22.8%[内固定组]对15.8%[对照组]，p = 0.25）。在多变量竞争风险模型中对预先指定的协变量进行调整后，内固定减压并未导致LF风险增加（风险比1.21，95%可信区间0.74 - 1.98，p = 0.45）。内固定部位SRS后疼痛加剧（11%对14%，p = 0.55）、椎体压缩骨折（12%对22%，p = 0.04）和≥3级毒性反应（1%对1%，p = 1.00）的发生率并未增加。未观察到内固定失败。结论 在这项倾向评分匹配分析中，各队列之间LF和毒性反应相似，表明内固定减压不会显著影响脊柱SRS的疗效或安全性。因此，脊柱内固定可能不是SRS的禁忌证。有必要开展未来研究，在匹配人群中比较SRS与传统放疗在有内固定部位的效果。
