Department of Radiation Oncology, The Methodist Hospital and Weil-Cornell Medical College, Houston, Texas, USA.
Cancer. 2013 Jul 15;119(14):2654-9. doi: 10.1002/cncr.28118. Epub 2013 Apr 30.
The objective of this study was to evaluate local control and patterns of failure in pediatric patients with low-grade glioma (LGG) who received treatment with intensity-modulated radiation therapy (IMRT).
In total, 39 children received IMRT after incomplete resection or disease progression. Three methods of target delineation were used. The first was to delineate the gross tumor volume (GTV) and add a 1-cm margin to create the clinical target volume (CTV) (Method 1; n = 19). The second was to add a 0.5-cm margin around the GTV to create the CTV (Method 2; n = 6). The prescribed dose to the GTV was the same as dose to the CTV for both Methods 1 and 2 (median, 50.4 grays [Gy]). The final method was dose painting, in which a GTV was delineated with a second target volume (2TV) created by adding 1 cm to the GTV (Method 3; n = 14). Different doses were prescribed to the GTV (median, 50.4 Gy) and the 2TV (median, 41.4 Gy).
The 8-year progression-free and overall survival rates were 78.2% and 93.7%, respectively. Seven failures occurred, all of which were local in the high-dose (≥95%) region of the IMRT field. On multivariate analysis, age ≤5 years at time of IMRT had a detrimental impact on progression-free survival.
IMRT provided local control rates comparable to those provided by 2-dimensional and 3-dimensional radiotherapy. Margins ≥1 cm added to the GTV may not be necessary, because excellent local control was achieved by adding a 0.5-cm margin (Method 2) and by dose painting (Method 3).
本研究旨在评估接受调强放疗（IMRT）治疗的儿童低级别胶质瘤（LGG）患者的局部控制率和失败模式。
共有 39 名儿童在不完全切除或疾病进展后接受了 IMRT。使用了三种靶区勾画方法。第一种方法是勾画大体肿瘤体积（GTV），并在外围增加 1cm 边界来创建临床靶区（CTV）（方法 1；n=19）。第二种方法是在 GTV 周围增加 0.5cm 边界来创建 CTV（方法 2；n=6）。两种方法 GTV 处方剂量与 CTV 相同（中位数 50.4 戈瑞[Gy]）。最后一种方法是剂量涂画，其中 GTV 用 GTV 向外增加 1cm 勾画的第二个靶区（2TV）来定义（方法 3；n=14）。不同剂量用于 GTV（中位数 50.4Gy）和 2TV（中位数 41.4Gy）。
8 年无进展生存率和总生存率分别为 78.2%和 93.7%。7 例患者发生失败，均为 IMRT 高剂量（≥95%）区域的局部失败。多因素分析显示，IMRT 时年龄≤5 岁对无进展生存率有不良影响。
IMRT 提供的局部控制率与二维和三维放疗相当。GTV 增加≥1cm 的边界可能没有必要，因为增加 0.5cm 边界（方法 2）和剂量涂画（方法 3）可实现优异的局部控制。
