局限期小细胞肺癌海马保护脑预防性照射初步研究

A prospective study of hippocampal-avoidance prophylactic cranial irradiation in small cell lung cancer patients with limited stage

目的分析局限期小细胞肺癌放化疗后行海马保护的脑预防性照射(PCI)的可行性。方法2016-2019年于浙江省肿瘤医院对进行PCI的小细胞肺癌患者随机分至常规组22例与海马保护组18例。根据RTOG 0933试验勾画靶区,海马保护组采用容积调强弧形治疗(VMAT)技术,放疗结束后对患者进行霍普金斯言语测试及脑MRI随访。结果海马体积(4.01±1.57)cm3,海马回避区体积(20.13±4.14)cm3,海马保护区域D100%为(7.19±0.38)Gy,Dmax为(14.38±1.18)Gy。霍普金斯言语测试中,放疗后1个月与放疗前(测试3、测试4、学习数、保留百分比)相比,以及放疗后1个月与放疗后(测试3、学习数)相比,海马保护组较常规组下降程度低。平均随访时间(17.00±8.47)个月,共2例患者出现脑部转移,均为常规放疗组且转移灶位于海马保护区之外。结论采用VMAT技术进行海马保护的PCI在剂量学上具有可行性,测试结果提示海马保护对于记忆的保护作用,值得临床上进一步推广。

Objective To analyze the feasibility of hippocampal-avoidance(HA)prophylactic cranial irradiation(PCI)in small cell lung cancer patients(SCLC)(limited stage)after chemotherapy and thoracic radiation.Methods From June 2016 to March 2019,40 eligible SCLC patients were recruited and randomly divided into the routine PCI(n=22)and hippocampal-avoidance PCI(HA-PCI)groups(n=18).The HA zone was contoured according to the criteria of RTOG 0933.Volumetric-modulated arc therapy(VMAT)was adopted in the HA-PCI group.After radiotherapy,Hopkins verbal learning test(HVLT)and MRI were performed.Results The average hippocampus volume was(4.01±1.57)cm3,the average HA volume was(20.13±4.14)cm3,HA D100%was(7.19±0.38)Gy and HA Dmax was(14.38±1.18)Gy.During HVLT,1-month-after-PCI vs.before-PCI(trial3,trial4,learning,percent retained),1-month-after-PCI vs.after-PCI(trial3,learning),HA-PCI cohort showed advantages over PCI in HVLT scores.The average follow-up time was(17.00±8.47)months.Two patients with brain metastases which were out of the HAZ received routine PCI.Conclusions PCI using VMAT technology to protect hippocampus is feasible in dosimetry.The test results indicate that the protective effect of hippocampus protection on memory is worthy of further promotion in clinical practice.