Department of Radiation Oncology, Cleveland Clinic Radiation Oncology, Cleveland, Ohio; Rose Ella Burkhardt Brain Tumor and Neuro-oncology Center, Cleveland, Ohio.
Case Western Reserve University, Cleveland, Ohio.
Pract Radiat Oncol. 2017 Nov-Dec;7(6):e391-e399. doi: 10.1016/j.prro.2017.04.003. Epub 2017 Apr 12.
Pulsed reduced dose rate (PRDR) is a reirradiation technique that potentially overcomes volume and dose limitations in the setting of previous radiation therapy for recurrent central nervous system (CNS) tumors. Intensity modulated radiation therapy (IMRT) has not yet been reported as a PRDR delivery technique. We reviewed our IMRT PRDR outcomes and toxicity and reviewed the literature of available PRDR series for CNS reirradiation.
A total of 24 patients with recurrent brain tumors received PRDR reirradiation between August 2012 and December 2014. Twenty-two patients were planned with IMRT. Linear accelerators delivered an effective dose rate of 0.0667 Gy/minute. Data collected included number of prior interventions, diagnosis, tumor grade, radiation therapy dose and fractionation, normal tissue dose, radiation therapy planning parameters, time to progression, overall survival, and adverse events.
The median time to PRDR from completion of initial radiation therapy was 47.8 months (range, 11-389.1 months). The median PRDR dose was 54 Gy (range, 38-60 Gy). The mean planning target volume was 369.1 ± 177.9 cm. The median progression-free survival and 6-month progression-free survival after PRDR treatment was 3.1 months and 31%, respectively. The median overall survival and 6-month overall survival after PRDR treatment was 8.7 months and 71%, respectively. Fifty percent of patients had ≥4 chemotherapy regimens before PRDR. Toxicity was similar to initial treatment, including no cases of radiation necrosis.
IMRT PRDR reirradiation is a feasible and appropriate treatment strategy for large volume recurrent CNS tumors resulting in acceptable overall survival with reasonable toxicity in our patients who were heavily pretreated. Prospective studies are necessary to determine the optimal timing of PRDR reirradiation, the role of concurrent systemic agents, and the ideal patient population who would receive the maximal benefit from this treatment approach.
Intensity modulated radiation therapy (IMRT) has not yet been reported as a pulsed reduced dose rate (PRDR) delivery technique for recurrent brain tumors and may allow for safe and comprehensive reirradiation for large volume tumors. We reviewed our IMRT PRDR outcomes and toxicity and reviewed the literature of available PRDR series for recurrent central nervous system tumors. We conclude that IMRT PRDR reirradiation is a feasible and appropriate treatment strategy for large volume recurrent brain tumors resulting in acceptable overall survival with reasonable toxicity in our patients who were heavily pretreated.
脉冲低剂量率（PRDR）是一种再放疗技术，它有可能克服在以前的放疗后复发的中枢神经系统（CNS）肿瘤的体积和剂量限制。强度调制放疗（IMRT）尚未被报道为 PRDR 传递技术。我们回顾了我们的 IMRT PRDR 结果和毒性，并回顾了现有的 CNS 再放疗 PRDR 系列的文献。
共有 24 例复发性脑肿瘤患者于 2012 年 8 月至 2014 年 12 月接受 PRDR 再放疗。22 例患者采用 IMRT 计划。直线加速器的有效剂量率为 0.0667 Gy/min。收集的数据包括先前干预的次数、诊断、肿瘤分级、放疗剂量和分割、正常组织剂量、放疗计划参数、进展时间、总生存和不良事件。
从初始放疗完成到 PRDR 的中位时间为 47.8 个月（范围为 11-389.1 个月）。PRDR 剂量的中位数为 54 Gy（范围为 38-60 Gy）。平均靶区体积为 369.1±177.9 cm。PRDR 治疗后 3.1 个月和 6 个月的无进展生存率分别为 31%和 31%。PRDR 治疗后 8.7 个月和 71%的中位总生存率和 6 个月总生存率。50%的患者在 PRDR 前有≥4 种化疗方案。毒性与初始治疗相似，包括无放射性坏死病例。
对于大体积复发性 CNS 肿瘤，IMRT PRDR 再放疗是一种可行且合适的治疗策略，在我们接受过大量预处理的患者中，可获得可接受的总生存率和合理的毒性。需要前瞻性研究来确定 PRDR 再放疗的最佳时机、同期全身药物的作用以及从这种治疗方法中获得最大益处的理想患者人群。
强度调制放疗（IMRT）尚未被报道为复发性脑肿瘤的脉冲低剂量率（PRDR）传递技术，它可能为大体积肿瘤的安全和全面再放疗提供可能。我们回顾了我们的 IMRT PRDR 结果和毒性，并回顾了现有的 CNS 肿瘤再放疗 PRDR 系列的文献。我们的结论是，对于大体积复发性脑肿瘤，IMRT PRDR 再放疗是一种可行且合适的治疗策略，在我们接受过大量预处理的患者中，可获得可接受的总生存率和合理的毒性。
