Abstract：
Because of improved survival of cancer patients, more patients irradiated for brain metastases develop intracerebral recurrences requiring subsequent courses of radiotherapy. Five studies focused on reirradiation with whole-brain radiation therapy (WBRT) after initial WBRT for brain metastases. Following the second WBRT course, improvement of clinical symptoms was found in 31-68% of patients. Rates of neurotoxicity, such as encephalopathy or cognitive decline, were reported in two studies (1.4% and 32%). In another study, severe or unexpected adverse events were not observed. Survival following the second WBRT course was generally poor, with median survival times of 2.9-4.1 months. The survival prognosis of patients receiving two courses of WBRT can be estimated by a scoring tool considering five prognostic factors. Three studies investigated reirradiation with single-fraction stereotactic radiosurgery (SF-SRS) following primary WBRT. One-year local control rates were 74-91%, and median survival times ranged between 7.8 and 14 months. Rates of radiation necrosis (RN) after reirradiation were 0-6%. Seven studies were considered that investigated re-treatment with SF-SRS or fractionated stereotactic radiation therapy (FSRT) following initial SF-SRS or FSRT. One-year local control rates were 60-88%, and the median survival times ranged between 8.3 and 25 months. During follow-up after reirradiation, rates of overall (asymptomatic or symptomatic) RN ranged between 12.5% and 30.4%. Symptomatic RN occurred in 4.3% to 23.9% of cases (patients or lesions). The risk of RN associated with symptoms and/or requiring surgery or corticosteroids appears lower after reirradiation with FSRT when compared to SF-SRS. Other potential risk factors of RN include the volume of overlap of normal tissue receiving 12 Gy at the first course and 18 Gy at the second course of SF-SRS, maximum doses ≥40 Gy of the first or the second SF-SRS courses, V12 Gy >9 cm3 of the second course, initial treatment with SF-SRS, volume of normal brain receiving 5 Gy during reirradiation with FSRT, and systemic treatment. Cumulative EQD2 ≤100-120 Gy2 to brain, <100 Gy2 to brainstem, and <75 Gy2 to chiasm and optic nerves may be considered safe. Since most studies were retrospective in nature, prospective trials are required to better define safety and efficacy of reirradiation for recurrent or progressive brain metastases.
摘要：
因为提高了癌症患者的生存率，更多接受脑转移治疗的患者发生脑内复发，需要随后的放射治疗疗程。五项研究集中在脑转移的初始WBRT后进行全脑放射治疗（WBRT）的再照射。在第二次WBRT课程之后，31-68%的患者临床症状得到改善。神经毒性率,如脑病或认知能力下降，在两项研究中报告（1.4%和32%）。在另一项研究中,未观察到严重或意外不良事件.第二次WBRT课程后的生存率普遍较差，中位生存时间为2.9-4.1个月。可以通过考虑五个预后因素的评分工具来估计接受两个疗程WBRT的患者的生存预后。三项研究调查了初次WBRT后单次立体定向放射外科（SF-SRS）的再照射。一年局部控制率为74-91%,中位生存时间为7.8~14个月.再照射后放射性坏死（RN）的发生率为0-6％。考虑了七项研究，研究了在初始SF-SRS或FSRT后使用SF-SRS或分次立体定向放射治疗（FSRT）的再治疗。一年局部控制率为60-88%,中位生存时间为8.3~25个月.在再次照射后的随访中，总体(无症状或有症状)RN的发生率在12.5%至30.4%之间.有症状的RN发生在4.3％至23.9％的病例（患者或病变）中。与SF-SRS相比，用FSRT再照射后，与症状和/或需要手术或皮质类固醇相关的RN的风险较低。RN的其他潜在风险因素包括在第一个疗程接受12Gy的正常组织的重叠量和在第二个疗程接受18Gy的SF-SRS，第一或第二SF-SRS疗程的最大剂量≥40Gy，第二道V12Gy>9cm3，用SF-SRS进行初始治疗，在用FSRT再照射期间接受5Gy的正常大脑体积，和系统治疗。脑累积EQD2≤100-120Gy2，脑干<100Gy2，和<75Gy2交叉和视神经可能被认为是安全的。由于大多数研究都是回顾性的，需要前瞻性试验来更好地确定复发或进展性脑转移再放疗的安全性和有效性.
