Objectives

Stereotactic ablative radiotherapy (SABR) is used to treat inoperable early-stage, node-negative small cell lung cancer (SCLC). We performed a systematic review and meta-analysis of the literature on SABR for T1-2N0M0 SCLC to summarize outcomes including local control (LC), overall survival (OS), recurrence rates, and toxicity.

Materials and Methods

This study was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) and MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. A systematic review of PubMed and EMBASE (inception to April 2021) was conducted. Two authors independently reviewed articles for inclusion and extracted study-level data. Random-effects meta-analysis was conducted using R (version 3.6.2) at a significance threshold of .05.

Results

Eleven studies were identified in the systematic review and seven (399 patients) were selected for meta-analysis. Inoperability was noted as the indication for SABR in 94% (75-100%) of patients. Median follow-up and tumor size were 19.5 months (11.9-32) and 24 mm (19-29), respectively. Chemotherapy and PCI use rates were 44.1% (95% confidence interval [CI], 27.0-61.9%) and 13.8% (95% CI, 0.4-41.2%), respectively. Local control was 97.3% (95% CI, 92.3-99.8%) at 1 year and 95.7% (95% CI, 74.2-100.0%) at 2 years. Overall survival was 86.3% (95% CI, 74.4-94.9%) at 1 year and 63.7% (95% CI, 45.7-79.9%) at 2 years. Nodal and distant recurrence rates were 17.8% (95% CI, 7.5-31.2%) and 26.9% (95% CI, 7.4-53.0%), respectively. The rates of grade 1, grade 2, and grade 3 toxicity (CTCAE) were 12.6% (95% CI, 6.7-19.9%), 6.7% (95% CI, 3.3-11.2%), and 1.4% (95% CI, 0.0-5.3%), respectively. No grade 4 or 5 events were observed across the studies.

Conclusion

SABR for inoperable early-stage, node-negative SCLC is locally effective with limited toxicity. Prospective studies are required to further evaluate the role of SABR for patients at higher risk of toxicity with surgery or combined chemoradiation.

中文翻译：

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T1-2N0M0 小细胞肺癌的立体定向消融放疗：系统评价和荟萃分析

目标

立体定向消融放疗 (SABR) 用于治疗无法手术的早期淋巴结阴性小细胞肺癌 (SCLC)。我们对 T1-2N0M0 SCLC 的 SABR 文献进行了系统回顾和荟萃分析，以总结包括局部控制 (LC)、总生存期 (OS)、复发率和毒性在内的结果。

材料和方法

本研究是根据 PRISMA（系统评价和荟萃分析的首选报告项目）和 MOOSE（流行病学观察性研究的荟萃分析）指南进行的。对 PubMed 和 EMBASE（成立至 2021 年 4 月）进行了系统评价。两位作者独立审查了纳入的文章并提取了研究级数据。使用 R（版本 3.6.2）以 0.05 的显着性阈值进行随机效应荟萃分析。

结果

在系统评价中确定了 11 项研究，并选择了 7 项（399 名患者）进行荟萃分析。在 94% (75-100%) 的患者中，不能手术被认为是 SABR 的指征。中位随访时间和肿瘤大小分别为 19.5 个月 (11.9-32) 和 24 mm (19-29)。化疗和 PCI 使用率分别为 44.1%（95% CI，27.0-61.9%）和 13.8%（95% CI，0.4-41.2%）。局部控制在 1 年时为 97.3%（95% CI，92.3-99.8%），在 2 年时为 95.7%（95% CI，74.2-100.0%）。1 年总生存率为 86.3%（95% CI，74.4-94.9%），2 年总生存率为 63.7%（95% CI，45.7-79.9%）。淋巴结和远处复发率分别为 17.8% (95% CI, 7.5-31.2%) 和 26.9% (95% CI, 7.4-53.0%)。1 级、2 级和 3 级毒性 (CTCAE) 的发生率分别为 12.6%（95% CI，6.7-19.9%）、6.7%（95% CI，3.3-11.2%）和 1。分别为 4%（95% CI，0.0-5.3%）。在这些研究中未观察到 4 级或 5 级事件。

结论

SABR 对不能手术的早期淋巴结阴性 SCLC 局部有效，毒性有限。需要进行前瞻性研究以进一步评估 SABR 对手术或联合放化疗毒性风险较高的患者的作用。