Grant Jonathan D, Sobremonte Angela, Hillebrandt Evangeline, Allen Pamela K, Gomez Daniel R
Department of Radiation Oncology, MD Anderson Cancer Center, 1515 Holcombe Blvd Unit 097, Houston, TX, 77030, USA.
Radiat Oncol. 2015 Jan 31;10:32. doi: 10.1186/s13014-015-0332-9.
To investigate the influence of induction chemotherapy (ICT) on dosimetric outcomes in patients with inoperable non-small cell lung cancer (NSCLC) treated with definitive chemoradiation (CRT).
30 patients with inoperable stage II-III NSCLC treated with 2-4 cycles of ICT followed by definitive CRT to ≥ 60 Gy were selected. Tumor response to chemotherapy was scored by RECIST criteria. Treatment plans based on tumor extent prior to chemotherapy were generated based on equivalent planning constraints and techniques as the original post-chemotherapy plans. Dosimetric parameters predictive of toxicity for lung, esophagus, heart, and spinal cord were compared amongst the pre- and post-ICT plans.
The majority of patients (70%) experienced an overall reduction in GTV size between the pre-ICT imaging and the time of simulation. Comparing pre-and post-ICT diagnostic imaging, 5 patients met the RECIST criteria for response, 23 were classified as stable, and 2 experienced disease progression on diagnostic imaging. Despite a significantly reduced GTV size in the post-ICT group, no systematic improvements in normal tissue doses were seen amongst the entire cohort. This result persisted amongst the subgroup of patients with larger pre-ICT GTV tumor volumes (>100 cc(3)). Among patients with RECIST-defined response, a significant reduction in lung mean dose (1.9 Gy absolute, median 18.2 Gy to 16.4 Gy, p = 0.04) and V20, the percentage of lung receiving 20 Gy (3.1% absolute, median 29.3% to 26.3%, p = 0.04) was observed. In the non-responding group of patients, an increased esophageal V50 was found post-chemotherapy (median 28.9% vs 30.1%, p = 0.02).
For patients classified as having a response by RECIST to ICT, modest improvements in V20 and mean lung dose were found. However, these benefits were not realized for the cohort as a whole or for patients with larger tumors upfront. Given the variability of tumor response to ICT, the a priori impact of induction chemotherapy to reduce RT dose to normal tissue in these patients is minimal in the setting of modern treatment planning.
探讨诱导化疗（ICT）对接受根治性放化疗（CRT）的不可切除非小细胞肺癌（NSCLC）患者剂量学结果的影响。
选取30例接受2 - 4周期ICT治疗，随后接受≥60 Gy根治性CRT的不可切除II - III期NSCLC患者。根据实体瘤疗效评价标准（RECIST）对化疗的肿瘤反应进行评分。基于化疗前肿瘤范围，按照与原始化疗后计划相同的等效计划约束和技术生成治疗计划。比较ICT前后计划中预测肺、食管、心脏和脊髓毒性的剂量学参数。
大多数患者（70%）在ICT前成像与模拟时之间的GTV大小总体减小。比较ICT前后的诊断成像，5例患者符合RECIST反应标准，23例分类为稳定，2例在诊断成像时疾病进展。尽管ICT后组的GTV大小显著减小，但在整个队列中未观察到正常组织剂量有系统性改善。在ICT前GTV肿瘤体积较大（>100 cc³）的患者亚组中，这一结果仍然存在。在RECIST定义为有反应的患者中，观察到肺平均剂量显著降低（绝对降低1.9 Gy，中位数从18.2 Gy降至16.4 Gy，p = 0.04）以及V20（接受20 Gy照射的肺组织百分比）降低（绝对降低3.1%，中位数从29.3%降至26.3%，p = 0.04）。在无反应的患者组中，化疗后食管V50增加（中位数28.9%对30.1%，p = 0.02）。
对于根据RECIST标准对ICT有反应的患者，V20和肺平均剂量有适度改善。然而，对于整个队列或初始肿瘤较大的患者而言，这些益处并未实现。鉴于肿瘤对ICT反应的变异性，在现代治疗计划背景下，诱导化疗对降低这些患者正常组织放疗剂量的先验影响极小。
