20例鼻咽癌调强放疗初步结果分析

Preliminary Analysis of Intensity Modulated Radiation Therapy for 20 Patients with Nasopharyngeal Carcinoma

目的:分析调强放疗(intensity modulated radiotherapy,IMRT)在鼻咽癌应用的初步结果。方法:对天津医科大学附属肿瘤医院2007年1月至2008年4月20例经病理证实的鼻咽癌患者进行全程IMRT,其中Ⅱ期5例,Ⅲ期13例,Ⅳa期2例。鼻咽肿瘤(PTV)和颈部转移淋巴结(PTVnd)处方剂量为69.96Gy,鼻咽区域及上颈部临床靶区(PTV1)处方剂量为60.06Gy,下颈部锁骨上区域(PTV2)处方剂量为50.96Gy。腮腺50%体积≤35Gy,晶体、垂体、颞颌关节、下颌骨及颞叶的最高限量分别为9、54、60、70、60Gy,脑干、脊髓、视神经、视交叉的计划危及器官区(Dlanningorgan at risk volume,PRV)1%体积最高限量分别为54、40、54、54Gy。全组病例于IMRT前均行1～2个周期化疗。结果:中位随访时间为14个月,1例因鼻咽癌骨转移、呼吸衰竭死亡。1年总生存率为94.1%,3例发生远处转移,急性反应以1、2级为主,其中口干多集中在1级(17例),1级口腔黏膜急性反应3例,2级12例。PTV、PTVnd、PTV1、PTV2的平均剂量均值分别为73.4、74.1、67.8、54.1Gy。左、右腮腺的平均剂量分别为43.9、41.9Gv。左、右晶体最高剂量平均值分别为8.06、8.12Gy,脑干、脊髓、左、右视神经、视交叉PRV最大剂量平均值分别为60.6、46.6、50.0、55.0、56.0Gy。结论:IMRT技术能对鼻咽癌的各靶区达到较好的剂量分布,可获得理想的局部区域控制,对正常组织器官有较好的保护作用。

Objective： To report the preliminary results of intensity modulated radiation therapy （IMRT） for 20 nasopharyngeal carcinoma patients. Methods： A total of 20 patients with nasopharyngeal carcinoma received IMRT in our hospital between January 2007 and April 2008. Five patients were of stage Ⅱ, 13 patients were of stage Ⅲ, and 2 patients were of stageⅣ. The prescribed dose 69.96 Gy was delivered to the gross tumor volume （PTV） and positive neck nodes （PTVnd）; 59.36 Gy to the clinical target volume （PTVl）, covering the upper neck and area around the nasopharynx; and 50.96 Gy to the low neck and supraclavicular area （PTV2）. The dose to 50% of the parotid was ≤35 Gy. The maximum dose to the lens, pituitary gland, tempo- to-mandibular joint, mandible, and temporal lobe was 9, 54, 60, 70, and 60 Gy. The maximum dose to the brainstem, spinal cord, optic nerve and optic chiasma （PRV） was 54, 40, 54, and 54 Gy, respectively. All of the patients received 1 or 2 circles of chemothrapy before IMRT. Results： The median follow-up time was 14 months. The one-year overall survival was 94.1%. One patient died of osseous metastasis and respiratory failure and 3 patients developed distant metastasis. Acute toxicity was mostly Grade Ⅰ to Grade Ⅱ. Seventeen patients had grade Ⅰ xerostomia. Three patients suffered from grade Ⅰ acute oral mucosa reaction and 12 patients had grade Ⅱ acute oral mucosa reaction. Analysis of the dose-volume histograms （DVHs） showed that the mean dose delivered to the PTV, PTVnd, PTV1 and PTV2 was 73.4, 74.1, 67.8, and 54.1 Gy, respectively. The median dose to 50% of the right and left parotid glands was 43.9 Gy and 41.9 Gy, respcetively. The average value of maximum dose to the left and right lens was 8.06 and 8.12 Gy, respectively. The average val- ue of maximum dose to the brainstem, spinal cord, left and right optic nerve and optic chiasma PRV was 60.6, 46.6, 50.0, 55.0, and 56.0 Gy, respectively. Conclusion： IMRT can achieve satisfactory dose distribution to nasopharyngeal carcinoma and surrounding tissues in NPC patients, protect normal tissues during the treatment and improve local control rate.