Stereotactic body radiation therapy (SBRT) improves local control and overall survival compared to conventionally fractionated radiation for stage I non-small cell lung cancer (NSCLC)

<b>Background:</b> Stereotactic body radiotherapy (SBRT) has been adopted as the standard of care for inoperable early-stage non-small cell lung cancer (NSCLC), with local control rates consistently &gt;90%. However, data directly comparing the outcomes of SBRT with those of conventionally fractionated radiotherapy (CONV) is lacking. <b>Material and methods:</b> Between 1990 and 2013, 497 patients (525 lesions) with early-stage NSCLC (T1-T2N0M0) were treated with CONV (<i>n</i> = 127) or SBRT (<i>n</i> = 398). In this retrospective analysis, five endpoints were compared, with and without adjusting for clinical and dosimetric factors. Competing risks analysis was performed to estimate and compare the cumulative incidence of local failure (LF), nodal failure (NF), distant failure (DF) and disease progression. Overall survival (OS) was estimated by the Kaplan–Meier method and compared by the Cox regression model. Propensity score (PS) matched analysis was performed based on seven patient and clinical variables: age, gender, Karnofsky performance status (KPS), histology, T stage, biologically equivalent dose (BED), and history of smoking. <b>Results:</b> The median dose delivered for CONV was 75.6 Gy in 1.8–2.0 Gy fractions (range 60–90 Gy; median BED = 89.20 Gy) and for SBRT 48 Gy in four fractions (45–60 Gy in three to five fractions; median BED = 105.60 Gy). Median follow-up was 24.4 months, and 3-year LF rates were 34.1% with CONV and 13.6% with SBRT (<i>p</i> &lt; .001). Three-year OS rates were 38.9 and 53.1%, respectively (<i>p</i> = .018). PS matching showed a significant improvement of OS (<i>p</i> = .0497) for SBRT. T stage was the only variable correlating with all five endpoints. <b>Conclusion:</b> SBRT compared to CONV is associated with improved LF rates and OS. Our data supports the continued use and expansion of SBRT as the standard of care treatment for inoperable early-stage NSCLC.

背景：立体定向体部放疗（Stereotactic body radiotherapy, SBRT）已成为不可手术早期非小细胞肺癌（non-small cell lung cancer, NSCLC）的标准治疗方案，其局部控制率稳定维持在90%以上。然而，目前尚缺乏直接比较SBRT与常规分割放疗（conventionally fractionated radiotherapy, CONV）疗效的相关数据。
材料与方法：1990年至2013年间，共纳入497例早期NSCLC（T1-T2N0M0）患者（共525个病灶），分别接受CONV治疗（n=127）或SBRT治疗（n=398）。本项回顾性分析对5项结局指标分别进行了未校正与校正临床及剂量学因素后的组间比较。采用竞争风险分析法估算并比较局部失败（local failure, LF）、区域淋巴结失败（nodal failure, NF）、远处失败（distant failure, DF）及疾病进展的累积发生率。总生存期（overall survival, OS）采用卡普兰-迈耶法（Kaplan–Meier method）估算，并通过Cox回归模型进行组间比较。基于年龄、性别、卡氏功能状态评分（Karnofsky performance status, KPS）、组织学类型、T分期、生物等效剂量（biologically equivalent dose, BED）及吸烟史7项患者与临床特征，开展倾向得分（propensity score, PS）匹配分析。
结果：CONV组中位给药剂量为75.6 Gy，分割剂量1.8~2.0 Gy（总剂量范围60~90 Gy；中位生物等效剂量BED=89.20 Gy）；SBRT组中位给药剂量为48 Gy，分4次给药（3~5次分割的总剂量范围45~60 Gy；中位BED=105.60 Gy）。中位随访时间为24.4个月，CONV组与SBRT组的3年局部失败率分别为34.1%与13.6%（p<0.001）。两组3年总生存率分别为38.9%与53.1%（p=0.018）。倾向得分匹配分析显示，SBRT可显著改善患者总生存期（p=0.0497）。T分期是唯一与全部5项结局指标均存在相关性的变量。
结论：与CONV相比，SBRT可显著提升局部失败控制率与总生存期。本研究数据支持将SBRT持续作为不可手术早期NSCLC的标准治疗方案，并进一步推广其临床应用。