Jen Y M, Hsu W L, Chen C Y, Hwang J M, Chang L P, Lin Y S, Su W F, Chen C M, Liu D W, Chao H L
Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Int J Radiat Oncol Biol Phys. 2001 Oct 1;51(2):344-8. doi: 10.1016/s0360-3016(01)01631-5.
To report our observation of excessive temporal lobe necrosis in nasopharyngeal carcinoma (NPC) patients treated with 160 cGy b.i.d. radiotherapy technique. During the same period, patients treated with 120 cGy b.i.d. have not shown a similar tendency. Our experience may be useful for designing unconventional radiotherapy regimens for NPC patients.
During the period from October 1991 to January 1998, 81 M0, previously untreated NPC patients completed altered fractionated radiotherapy. Seventy patients were treated with the hyperfractionated technique, and 11 were treated using the accelerated-hyperfractionated scheme. Hyperfractionated radiotherapy was delivered using 120 cGy b.i.d. separated by 6-h intervals throughout the course. A minimum tumor dose of 8000 cGy was the standard dose over an 8-week period. With the accelerated-hyperfractionated scheme, 160 cGy was given twice daily, also with an interval of 6 h. The minimum tumor dose ranged between 6840 and 7640 cGy, with 7 of the 11 patients receiving 7000 cGy. The arrangement of portals was the same for both regimens. The follow-up period for patients alive was from 32 to 102 months with a median of 61 months for the hyperfractionated patients. For the accelerated-hyperfractionated group, it ranged from 67 to 82 months with a median of 72 months. No patient was lost to follow-up.
At the time of analysis, 49 of the 70 patients in the hyperfractionated group were alive. In the accelerated group, 8 of the 11 patients were alive. The estimated radiation dose to the temporal lobe for the hyperfractionated group was 6000-7440 cGy with a median of 7080 cGy. For the accelerated-hyperfractionated group, the dose range was 4480-6700 cGy with a median of 6400 cGy. Of the 70 patients treated with hyperfractionated radiotherapy, none developed symptomatic brain necrosis, despite the higher total dose to the temporal lobe in general. In contrast, 3 of the 11 (27%) patients irradiated using the accelerated-hyperfractionated regimen suffered from temporal lobe necrosis at 16, 19, and 40 months after completion of radiotherapy.
An excessive incidence of temporal lobe necrosis was noted when an accelerated-hyperfractionated regimen with 160 cGy b.i.d. was used in NPC patients with a median brain dose of 6400 cGy. There has been no such event in patients treated using a hyperfractionated regimen with 120 cGy and a median brain dose of 7000 cGy. The real causes of this discrepancy are not known. However, a high sensitivity of the human brain to a change in fraction size may play a role.
报告我们对采用每日两次160 cGy放射治疗技术的鼻咽癌（NPC）患者出现颞叶过度坏死的观察结果。同期，采用每日两次120 cGy治疗的患者未表现出类似倾向。我们的经验可能有助于为NPC患者设计非常规放射治疗方案。
1991年10月至1998年1月期间，81例M0期、未经治疗的NPC患者完成了分次放疗方案调整。70例患者采用超分割技术治疗，11例采用加速超分割方案治疗。超分割放疗全程采用每日两次120 cGy，间隔6小时。8周内最小肿瘤剂量8000 cGy为标准剂量。采用加速超分割方案时，每日两次给予160 cGy，间隔同样为6小时。最小肿瘤剂量在6840至7640 cGy之间，11例患者中有7例接受7000 cGy。两种方案的射野安排相同。存活患者的随访期为32至102个月，超分割治疗患者的中位随访期为61个月。加速超分割组的随访期为67至82个月，中位随访期为72个月。无患者失访。
分析时，超分割组70例患者中有49例存活。加速组11例患者中有8例存活。超分割组颞叶的估计辐射剂量为6000 - 7440 cGy，中位剂量为7080 cGy。加速超分割组的剂量范围为4480 - 6700 cGy，中位剂量为6400 cGy。70例接受超分割放疗的患者中，无一例发生有症状的脑坏死，尽管总体上颞叶接受的总剂量较高。相比之下，11例采用加速超分割方案放疗的患者中有3例（27%）在放疗结束后16、19和40个月出现颞叶坏死。
对于中位脑剂量为6400 cGy的NPC患者，采用每日两次160 cGy的加速超分割方案时，颞叶坏死发生率过高。采用每日两次120 cGy、中位脑剂量为7000 cGy的超分割方案治疗的患者未出现此类情况。这种差异的真正原因尚不清楚。然而，人脑对分次剂量变化的高敏感性可能起了作用。
