Patterns of failure following high-dose 3-D conformal radiotherapy for high-grade astrocytomas: A quantitative dosimetric study
Patterns of failure following high-dose 3-D conformal radiotherapy for high-grade astrocytomas: A quantitative dosimetric study
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DOI：
10.1016/s0360-3016(98)00266-1
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发表时间：
1999-01-01
影响因子：
7
通讯作者：
Sandler, HM
中科院分区：
文献类型：
--
作者：
Lee, SW;Fraass, BA;Sandler, HM
目的：分析高级别星形细胞瘤患者接受高剂量适形放射治疗（CRT）的失败模式，使用定量技术计算CT或MR定义的复发体积所接受的剂量，并评估本剂量递增研究中使用的最终靶体积边界是否需要在进一步递增前重新定义。方法和材料：在4/89和10/95之间，71名患有高级别幕上星形细胞瘤的患者进入了I/II期剂量递增研究，使用3-D治疗计划和适形放疗。所有患者均接受70或80戈伊的常规治疗，每日剂量为1.8-2.0戈伊。临床和计划靶体积（CTV，PTV）由连续较小的体积组成，最终PTV定义为增强病变加0.5 cm边缘。截至10/95，47例患者有疾病复发/进展的CT或MR证据。在47名患者中，36名在复发时获得的扫描被输入到三维放射治疗计划系统中。在确定复发肿瘤体积后，将复发扫描数据集与治疗前CT数据集配准，以便准确计算治疗期间复发肿瘤体积接受的实际剂量，然后使用剂量-体积直方图进行剂量学分析。复发分为几类：1）“中心”，其中95%或更多的复发肿瘤体积（V-复发）在D-95内，即高剂量治疗的区域（处方剂量的95%）; 2）“现场”，其中80%或更多的V-复发在D-95等剂量表面内; 3）边缘型，即20%~ 80%的V型复发位于D-95面内; 4）外部型，即小于20%的V型复发位于D-95面内。在29例孤立性复发中，26例位于中央，3例位于边缘，无一例位于外侧。在7例患者中观察到多个复发性病变：3例患者仅具有多个中心和/或视野内病变，3例患者具有中心和/或视野内病变伴额外的小边缘或外部病变，1例患者具有6个外部和1个中心病变。由于在最终分析中使用了总复发体积，因此7例多发性复发病灶患者中有6例被归类为中心/病灶内类别。对36例可评价患者的分析表明，36例患者中有32例（89%）因中央或区域内复发而失败，3/36例（8%）有明显的边缘复发成分，而只有1/36（3%）可以清楚地标记为主要在高剂量区域之外失败。7例患者有多次复发，但只有1例在高剂量区域外有大体积复发。本研究表明，大部分患者在高剂量（70或80戈伊）适形照射后发生的复发位于中心：只有1/36例患者（7个复发病灶）的复发体积超过50%，超出了先前接受高剂量治疗的区域。因此，基于相同的靶体积定义标准，进一步剂量递增至90戈伊（及以上）似乎是合理的。(C)1998年爱思唯尔科学公司
Purpose: To analyze the failure patterns for patients with high-grade astrocytomas treated with high-dose conformal radiotherapy (CRT) using a quantitative technique to calculate the dose received by the CT- or MR-defined recurrence volume and to assess whether the final target volume margin used in the present dose escalation study requires redefinition before further escalation.Methods and Materials: Between 4/89 and 10/95, 71 patients with high-grade supratentorial astrocytomas were entered in a phase I/II dose escalation study using 3-D treatment planning and conformal radiotherapy. All patients were treated to either 70 or 80 Gy in conventional daily fractions of 1.8-2.0 Gy. The clinical and planning target volumes (CTV, PTV) consisted of successively smaller volumes with the final PTV defined as the enhancing lesion plus 0.5 cm margin. As of 10/95, 47 patients have CT or MR evidence of disease recurrence/progression. Of the 47 patients, 36 scans obtained at the time of recurrence were entered into the 3-D radiation therapy treatment planning system. After definition of the recurrent tumor volumes, the recurrence scan dataset was registered with the pretreatment CT dataset so that the actual dose received by the recurrent tumor volumes during treatment could be accurately calculated and then analyzed dosimetrically using dose-volume histograms. Recurrences were divided into several categories: 1) "central," in which 95% or more of the recurrent tumor volume (V-recur) was within D-95, the region treated to high dose (95% of the prescription dose); 2) "in-field," in which 80% or more of V-recur was within the D-95 isodose surface; 3) "marginal," when between 20 and 80% of V-recur was inside the D-95 surface; 4) "outside," in which less than 20% of V-recur was inside the D-95 surface.Results: In 29 of 36 patients, a solitary lesion was seen on recurrence scans. Of the 29 solitary recurrences, 26 were central, 3 were marginal, and none were outside. Multiple recurrent lesions were seen in seven patients: three patients had multiple central and/or in-field lesions only, three patients had central and/or in-field lesions with additional small marginal or outside lesions, and one patent had 6 outside and one central lesion. Since total recurrence volume was used in the final analysis, 6 of the 7 patients with multiple recurrent lesions were classified into central/in-field category.Conclusion: Analysis of the 36 evaluable patients has shown that 32 of 36 patients (89%) failed with central or in-field recurrences, 3/36 (8%) had a significant marginal component to the recurrence, whereas only 1/36 (3%) could be clearly labeled as failing mainly outside the high-dose region. Seven patients had multiple recurrences, but only 1 of 7 had large-volume recurrences outside the high-dose region. This study shows that the great majority of patient recurrences that occur after high-dose (70 or 80 Gy) conformal irradiation are centrally located: only 1/36 patients (with 7 recurrent lesions) had more than 50% of the recurrence volume outside the region previously treated to high dose. Further dose escalation to 90 Gy (and beyond) thus seems reasonable, based on the same target volume definition criteria. (C) 1998 Elsevier Science Inc.