鼻咽癌照射靶体积划定的临床探讨

Initial study of the clinical target volume delineation for radiotherapy of nas opharyngeal carcinoma

目的 通过分析针对靶体积逐步缩野放疗的临床结果 ,初步探讨鼻咽癌照射靶体积划定的合理性。方法 共 81例初治鼻咽癌患者进入研究 ,按 1992年福州分期Ⅰ、Ⅱ、Ⅲ和Ⅳa期分别为4、2 3、35和 19例。 4 3例接受单纯放疗 ,38例接受放化综合治疗。将照射靶体积划分为鼻咽大体肿瘤体积 (GTVnx)、颈部大体肿瘤体积 (GTVnd)、临床靶体积 1(CTV1)、临床靶体积 2 (CTV2 ) ,相应计划靶体积分别为PTVnx、PTVnd、PTV1、PTV2。处方剂量PTVnx6 0～ 76Gy ,PTVnd 6 2～ 6 6Gy ,PTV16 0Gy,PTV2 5 0～ 5 2Gy ;按靶体积的剂量要求逐步缩野照射。采用三维治疗计划系统对 8例不同期别患者的靶体积受照剂量进行计算 ,Kaplan Meier方法计算局部区域无进展生存率、无远地转移生存率和总生存率。结果 剂量计算结果显示 ,各靶体积均获得了所需的剂量覆盖。治疗后鼻咽及颈部肿瘤残留各 2例 ,残留病灶分别位于GTVnx及GTVnd内 ;鼻咽原发灶及颈部转移灶全消率均为 97.5 %。中位随访时间15个月 ,未观察到复发病例 ;2年局部区域无进展生存率、无远地转移生存率和总生存率分别为10 0 .0 %、96 .3%、10 0 .0 %。结论 采用上述靶体积划分方法进行放疗可获得较好局部控制 ,未观察到靶体积内、外和边缘的复发。但该划分方法的合理性和准确?

Objective To discuss the preliminary clinical result of targ et volum e delineation for radiotherapy of nasopharyngeal carcinoma(NPC). Methods From Jun e 2001 to March 2003, 81 NPC patients were studied:4 Stage Ⅰ,23 Ⅱ,35 Ⅲ,and 19 Ⅳa lesion,according to the Fuzhou 1992 Stage Classification System. Forty-thr e e patients were treated with radiotherapy alone, whereas 38 patients had radioth erapy combined with cisplatin-based chemotherapy. The target volume was describ ed as: the gross tumor volume of the nasopharynx (GTVnx) ,the cervical lymph no de (GTVnd), the clinical volume (CTV1), and the clinical volume 2 (CTV2) , resp ectively. The planning target volume(PTV), defined as the GTV or CTV plus a marg in, were PTVnx, PTVnd, PTV1 and PTV2 . The prescribed dose to the PTVnx, PTVnd, PTV1 and PTV2, were 60-76?Gy, 62-66?Gy, 60?Gy, and 50-52?Gy, respectively . The irra diation field was reduced step-by-step basing on the different planning target v olume. Eight patients with different stages were chosen to evaluate the dose dis tribution to the target volume on 3D planning system before the treatment. The l ocoregional progression-free, distant metastasis-free rate and overall surviva l rate were calculated by Kaplan-Meier statistical method. Resu lts The dose-vo lu me histogram analysis revealed that less than 9% of the average of the planning target volume received <95% of the prescribed dose. Local and regional residual tumor was observed in four patients, 2 in the GTVnx and 2 in the GTVnd.Its locor egional control rate was 97.5%. With a median follow-up of 15 months (range 9- 3 0 months), no local or region control failure was found in all patients. The loc oregional progression-free rate, distant metastasis-free rate, and overall sur v ival rate in two years were 100.0%, 96.3%, and 100.0% respectively. Conclusions S atisfiedactory locoregional control can be achieved by our method of defining th e target volume and radiation technique with no recurrent tumor observed inside, outside, or marginal to the target volume. Further study should be warranted to verify the rationality and accuracy of our understanding and endeavor in the ta rget volume in this study.