Abstract：
OBJECTIVE: There is limited clinical data for recommendations on how to deliver thoracic radiation therapy (TRT) concurrently with chemotherapy in limited-stage small cell lung cancer. We reviewed radiation therapy treatment plans in a randomized phase 2 trial comparing high-dose with standard-dose twice-daily TRT to assess treatment planning techniques, dose-volume data for target volumes and organs at risk (OARs), evaluate compliance with the protocol, associations with radiation-induced toxicity, and whether an imbalance in treatment planning parameters might be a reason for the large survival benefit of the higher dose (median overall survival 43.6 vs 22.6 months).
METHODS: In the study, 170 patients were to receive 4 courses of platinum/etoposide and were randomized to receive twice-daily TRT of 60 Gy/40 fractions (fx) or 45 Gy/30 fx. TRT treatment plans for those who received 1 or more fx of TRT (n = 166) were analyzed.
RESULTS: The most common treatment planning technique was 3-dimensional conformal radiation therapy (67%). The 75th percentile of the reported dose-volume parameters for the OARs were within the protocol-recommended limits for both groups. Mean doses to the esophagus of 25.5 Gy (IQR, 20.2-31.3; 60 Gy/40 fx) and 24.3 Gy (IQR, 20.3-27.5; 45 Gy/30 fx) were associated with 21% and 18% ≥ grade 3 acute esophagitis, respectively. In the 60 Gy/40 fx group, a mean dose to the lungs of 16.5 Gy (IQR, 15.8-16.9), V20 Gy of 29.5% (IQR, 28.8-30.4), and V5 Gy of 65.6% (IQR, 61.5-68.7) led to ≥ grade 3 pneumonitis in 4% of the patients. There was no ≥ grade 3 pneumonitis in the 45 Gy/30 fx group. The treatment planning techniques, the percentage change in volumes between original and redelineated OARs, planning target volumes, relative doses, and laterality were well balanced between the randomly assigned groups.
CONCLUSIONS: Considering the incidences of severe radiation-induced toxicities were within the range of other recent trials, the reported doses to the OARs appear to be safe. Treatment planning parameters were well balanced between the randomly assigned groups, supporting that the survival benefit of the twice-daily 60 Gy/40 fx TRT schedule was due to the higher dose.
METHODS: In the study, 170 patients were to receive 4 courses of platinum/etoposide and were randomized to receive twice-daily TRT of 60 Gy/40 fractions (fx) or 45 Gy/30 fx. TRT treatment plans for those who received 1 or more fx of TRT (n = 166) were analyzed.
RESULTS: The most common treatment planning technique was 3-dimensional conformal radiation therapy (67%). The 75th percentile of the reported dose-volume parameters for the OARs were within the protocol-recommended limits for both groups. Mean doses to the esophagus of 25.5 Gy (IQR, 20.2-31.3; 60 Gy/40 fx) and 24.3 Gy (IQR, 20.3-27.5; 45 Gy/30 fx) were associated with 21% and 18% ≥ grade 3 acute esophagitis, respectively. In the 60 Gy/40 fx group, a mean dose to the lungs of 16.5 Gy (IQR, 15.8-16.9), V20 Gy of 29.5% (IQR, 28.8-30.4), and V5 Gy of 65.6% (IQR, 61.5-68.7) led to ≥ grade 3 pneumonitis in 4% of the patients. There was no ≥ grade 3 pneumonitis in the 45 Gy/30 fx group. The treatment planning techniques, the percentage change in volumes between original and redelineated OARs, planning target volumes, relative doses, and laterality were well balanced between the randomly assigned groups.
CONCLUSIONS: Considering the incidences of severe radiation-induced toxicities were within the range of other recent trials, the reported doses to the OARs appear to be safe. Treatment planning parameters were well balanced between the randomly assigned groups, supporting that the survival benefit of the twice-daily 60 Gy/40 fx TRT schedule was due to the higher dose.
摘要：
目的：关于有限期（LS）小细胞肺癌（SCLC）如何在化疗的同时进行胸部放疗（TRT）的临床数据有限。我们回顾了一项随机II期试验中的放射治疗计划，比较高剂量与标准剂量每日两次TRT，以评估治疗计划技术。靶体积和危险器官(OAR)的剂量体积数据，评估对协议的遵守情况，与辐射诱导的毒性相关，以及治疗计划参数的不平衡是否可能是高剂量大生存获益的原因(中位总生存43.6vs.22.6个月）。
方法：170例患者接受4个疗程的铂/依托泊苷，并随机接受每日两次60Gy/40分数（fx）或45Gy/30fx的TRT。分析了那些接受一个或多个fx的TRT（n=166）的TRT治疗计划。
结果：最常见的治疗计划技术是3DCRT（67%）。两组OAR报告的剂量-体积参数的第75百分位数均在方案推荐的范围内。食道平均剂量为25.5Gy（IQR：20.2-31.3）[60Gy/40fx]和24.3Gy（IQR：20.3-27.5）[45Gy/30fx]与21％和18％≥3级急性食管炎相关，分别。在60Gy/40fx组中，肺的平均剂量为16.5Gy（IQR：15.8-16.9），V20Gy为29.5%(IQR:28.8-30.4),V5Gy为65.6％（IQR：61.5-68.7）导致4％的患者≥3级肺炎。45Gy组无≥3级肺炎。治疗计划技术，原始和重新划定的OAR之间的体积变化百分比，PTV音量,相对剂量,随机分配组之间的偏侧性平衡良好。
结论：考虑到严重辐射所致毒性的发生率在其他近期试验的范围内，报告给OAR的剂量似乎是安全的。随机分配组之间的治疗计划参数平衡良好，支持每日两次60Gy/40fxTRT方案的生存益处是由于较高的剂量。
方法：170例患者接受4个疗程的铂/依托泊苷，并随机接受每日两次60Gy/40分数（fx）或45Gy/30fx的TRT。分析了那些接受一个或多个fx的TRT（n=166）的TRT治疗计划。
结果：最常见的治疗计划技术是3DCRT（67%）。两组OAR报告的剂量-体积参数的第75百分位数均在方案推荐的范围内。食道平均剂量为25.5Gy（IQR：20.2-31.3）[60Gy/40fx]和24.3Gy（IQR：20.3-27.5）[45Gy/30fx]与21％和18％≥3级急性食管炎相关，分别。在60Gy/40fx组中，肺的平均剂量为16.5Gy（IQR：15.8-16.9），V20Gy为29.5%(IQR:28.8-30.4),V5Gy为65.6％（IQR：61.5-68.7）导致4％的患者≥3级肺炎。45Gy组无≥3级肺炎。治疗计划技术，原始和重新划定的OAR之间的体积变化百分比，PTV音量,相对剂量,随机分配组之间的偏侧性平衡良好。
结论：考虑到严重辐射所致毒性的发生率在其他近期试验的范围内，报告给OAR的剂量似乎是安全的。随机分配组之间的治疗计划参数平衡良好，支持每日两次60Gy/40fxTRT方案的生存益处是由于较高的剂量。
