局部残留和复发鼻咽癌分次立体定向放射治疗靶区设定的初步探讨

Preliminary Study of Target Volume Delineation for Locally Persistent and Recurrent Nasopharyngeal Carcinoma Treated with Fractionated Stereotactic Radiotherapy

[目的]探讨局部残留和复发鼻咽癌分次立体定向放射治疗(FSRT)靶区设定的合理性以及局部控制的影响因素。[方法]1999年9月至2005年12月,90例局部残留(34例)和复发(54例)鼻咽癌患者接受FSRT治疗,肿瘤最大径和体积范围分别为1.8～6.2cm(中位3.4cm)和0.8～24.7cm3(中位5.7cm3);计划靶区(PTV)定义为增强CT上的强化病灶外加2～3mm边缘,残留和复发病变的FSRT中位处方剂量分别为18Gy/3次和48Gy/6次。[结果]中位随访时间24.9个月(3.3～86.3个月),局部复发14例,其中,野内复发7例,86%(6/7)原病灶最大径<4cm;野外复发6例,67%(4/6)原病灶最大径>4cm;野内和野外同时复发1例。2和4年局部无失败生存率分别为83.1%和75.7%。肿瘤最大径>4cm和第2次局部复发者的4年局部无失败生存率均明显低于肿瘤最大径≤4cm(55.2%vs.82.1%,P=0.0369)和第1次局部复发和残留者(0vs.83.5%,P=0.0003)。[结论]对局部残留和复发鼻咽癌FSRT的靶区设定基本上是合理的,但对直径较大的肿瘤,PTV应适当扩大或改用其它治疗;肿瘤最大径>4cm或第二次局部复发的患者,其局部控制效果不佳。

[Purpose ] To investigate the reasonability of delineation of target volume and influencing factors of local control for locally persistent and recurrent nasopharyngeal carcinoma （NPC） treated with fractionated stereotactic radiation therapy （FSRT）. [Methods] From Sep. 1999 to Dec. 2005, 90 patients with locally persistent （n=34） and recurrent （n=56） NPC received FSRT. Tumor volume ranged from 0.8 to 24.7cm^3 （median 5.7） with a maximal diameter of 1.8 to 6.2cm （median 3.4）. Planning target volume （PTV） was defined by contrast-enhancing mass on CT plus a 2-3mm margin. Median FSRT dose was 18Gy in 3 fractions for persistent disease and 48Gy in 6 fractions for recurrent disease. [Results] Median follow-up was 24.9 mo（range 3.3-86.3）. Local recurreneee occurred in 14 patients. Among them, 7 were in-fleld recurrence; 86% （6/7）, tumor size 〈4cm in maximal diameter before FSRT; 6, out-field recurrence and 67% （4/6）, tumor size 〉4cm in maxiraal diameter before FSRT; one ease, concurrent recurrence in-field and out-field. The 2- and 4- year local failure-free survival rates were 83.1% and 75.7%, respectively. Four-year local failurefree survival rate in tumor size 〉4cm was significantly worse than that ≤4cm （55.2% vs. 82.1%, P=0.0369） and second local recurrence was worse than first local recurrence （0 vs. 83.5%, P= 0.0003）. [Conclusions] The delineation of target volume for local persistent and recurrent NPC treated with FSRT is basically reasonable. However, the tumor with longer diameter should be treated with extended PTV or change to other treatments. The patients with tumor size 〉4cm in maximal diameter or second local recurrence have poor local control with FSRT.