鼻咽癌IMRT脑干损伤的剂量体积研究

A dose volume analysis of brain stem injury after intensity-modulated radiotherapy in patients with nasopharyngeal carcinoma

目的探讨鼻咽癌IMRT发生放射性脑干损伤的发生率与照射剂量体积关系。方法回顾分析2005--2013年单治疗组连续收治初治鼻咽癌患者258例，统计脑干单位体积剂量，分析IMRT出现放射性脑干损伤的发生率与照射剂量体积的关系。Kaplan—Meier法计算生存率，脑干放射性损伤的影响因素采用Cox模型分析。结果2例L期、3例T。期患者发生放射性脑干损伤。脑千放射性损伤的3、5年发生率分别为1．6％、2．4％。损伤潜伏期为9～58个月（中位数19个月）。全组患者、T3期、T4期患者脑干D1%中位数分别为54．24、54．31、61．29Gy，5例损伤患者均〉60Gy；脑干Dmax中位数分别为59．22、59．45、66．37Gy，5例损伤患者均〉63Gy。单因素分析显示放射性脑干损伤发生与其D1％、Dmax、D0.1cm^3、D0.5cm^3、D1.0cm^3显著相关（P=0．01、0．01、0．01、0．01、0．01）。当脑干D1％≤60Gy、D1.0cm^3≤63Gy、D0.1cm^3≤60Gy、D0.5cm^3≤58Gy和D1．0cm^3≤56Gy时，发生放射性损伤概率可能较低（P=0．00、0．00、0．00、0．00、0．00）。结论鼻咽癌IMRT后出现放射性脑干损伤发生率较低。严格控制脑干受量，对降低放射性脑干损伤发生、提高患者远期生活质量可能有益。

Objective To investigate the relationship between the incidence of radiation-induced brain stem injury after intensity-modulated radiotherapy （IMRT） and the radiation dose volume in patients with nasopharyngeal carcinoma. Methods A retrospective analysis was performed on the data of 258 patients newly diagnosed with nasopharyngeal carcinoma who received IMRT in our group from 2005 to 2013. The radiation dose per unit volume of brain stem was analyzed. The relationship between the incidence of brain stem injury induced by IMRT and the radiation dose volume was studied. The survival rate was calculated using the Kaplan-Meier method. The factors influencing the radiation-induced brain stem injury were analyzed using the Cox regression model. Results Two patients with stage T3 disease and three patients with T4 disease had radiation-induced brain stem injury. The 3-and 5-year injury incidence rates were 1.6% and 2.4%, respectively. The latency ranged between 9 and 58 months, with a median latency of 19 months. The median D1% and Dmax for the brain stem were 54. 24 and 59.22 Gy in all patients, 54. 31 and 59.45 Gy in patients with stage T3 disease, and 61.29 and 66. 37 Gy in patients with stage T4 disease, respectively. In the five patients with brain stem injury, the D1% and Dmax were larger than 60 and 63 Gy, respectively. The univariate analysis showed that the incidence of radiation-induced brain stem injury was correlated with D1%, Dmax, D0.1cm^3 , D0.5cm^3, and D1.0cm^3 （ all P= 0. 01 ）. The incidence of radiation-induced brain stem injury was significantly lower in patients with D1% , Dmax, D0.1cm^3, D0.5cm^3, and D1.0cm^3 no larger than 60, 63, 60, 58, and 56 Gy, respectively （all P = 0. 00）. Conclusions The incidence of radiation-induced brain stem injury after IMRT is relatively low in patients with nasopharyngeal carcinoma. Strict control of the dose to the brain stem may help to reduce the incidence of brain stem injury and improve the long-term quality of life.