自适应放疗在鼻咽癌根治性放疗中作用初探

目的:评估自适应放疗（ART）在鼻咽癌调强放疗中剂量学特点及临床有效性、安全性。方法:选取2018年02月至2020年01月收治的行根治性调强放疗联合同步化疗的鼻咽癌患者共37例，随机分为ART组和常规放疗组。在放疗第5周的第一天，ART组患者重新定位做计划（定义为Plan-ART），后续的放疗由新计划完成。常规放疗组应用初始治疗计划至放疗结束，但在放疗第5周的第一天，重新扫描CT，并将初始计划复制到此CT上，得到新的剂量分布（定义为Plan-virtual）。比较Plan-ART和Plan-virtual的剂量学指标，比较两组患者治疗副反应、肿瘤完全缓解（CR）率及预后情况。结果:Plan-ART和Plan-virtual相比，pGTV和PTV1、PTV2的D2、平均剂量（Dmean）无明显差异。Plan-virtual中pGTV的95%的靶区体积受照射剂量（D95，下同）、D98、D100较Plan-ART中明显降低，PTV1、PTV2的D95、D98、D100较Plan-ART中明显降低，脊髓D2、腮腺平均剂量、30%体积所受照射剂量（V30）明显升高，差异有统计学意义。ART组和常规放疗组放疗后8周CR率分别为88.9%和78.9%（P=0.66）；2年无局部复发生存率分别为80.7%和70.8%（P=0.69）；2年无远处转移生存率分别为86.3%和83.2%（P=1.00）; 2年总生存率分别为87.5%和82.2%（P=0.53）。ART组患者口腔疼痛、口腔黏膜炎、食管炎/吞咽困难、口干发生率低于常规放疗组。结论:鼻咽癌根治性放疗患者在治疗的第5周重新定位制定放疗计划（即自适应放疗），能在保证靶区剂量的同时降低危及器官剂量，从而降低局部副反应，使患者获益。

The role of adaptive radiotherapy in radical radiotherapy for nasopharyngeal carcinoma

Objective:To evaluate the dosimetry characteristics,clinical efficacy,and safety of adaptive radiotherapy(ART) in intensity-modulated radiotherapy for nasopharyngeal carcinoma(NPC).Methods:37 patients with nasopharyngeal carcinoma who received radical concurrent intensity-modulated radiotherapy and chemotherapy from February 2018 to January 2020 were selected and randomly divided into the ART group and the conventional radiotherapy group.Patients in the ART group received repositioning and replan on the first day of the 5th week of radiotherapy,and the remaining radiotherapy was completed by the new plan.In the conventional radiotherapy group,the initial treatment plan was used until the end of radiotherapy,but on the first day of the 5th week of radiotherapy,a new CT scan was performed and the initial treatment plan was copied into this CT to obtain a new dose distribution(defined as Plan-virtual).The dosimetric indexes of Plan-ART and Plan-virtual were compared,and the side effects,complete response(CR) of tumor and prognosis of patients in the two groups were compared.Results:There was no significant difference between the Plan-ART group and the Plan-virtual group in D2 and mean dose(Dmean) of pGTV,PTV1 and PTV2.In Plan-virtual,D95,D98 and D100 of pGTV were significantly lower than those in Plan-ART,D95,D98 and D100 of PTV1 and PTV2 were significantly lower than those in Plan-ART,and D2 of the spinal cord,mean dose and V30 of the parotid gland were significantly higher,with statistical significance.The CR rates of the ART group and the conventional radiotherapy group at 8 weeks after radiotherapy were 88.9% and 78.9%,respectively(P=0.66).The 2-year local-regional recurrence-free survival rates were 80.7% and 70.8%,respectively(P=0.69).The 2-year distant metastasis-free survival rates were 86.3% and 83.2%,respectively(P=1.00).The 2-year overall survival rates were 87.5% and 82.2%,respectively(P=0.53).The incidence of oral pain,mucositis,esophagitis/dysphagia and dry mouth in the ART group was significantly lower than that in the conventional radiotherapy group.Conclusion:Adaptive radiotherapy at the beginning of the 5th week of radiotherapy for nasopharyngeal carcinoma can further optimize the dose coverage of the target,better protect the organs at risk,and reduce local side effects,so as to benefit patients.