218例鼻咽癌颈淋巴结转移规律的影像学分析

Analysis of Computed Tomography-Based Distribution of Metastatic Cervical Nodes in 218 Cases of Nasopharyngeal Carcinoma

背景与目的:鼻咽癌调强放射治疗要求在CT图像上准确划分需要照射的淋巴结和相应的亚临床靶区,前提就是总结出鼻咽癌淋巴结转移的影像学分布规律。本研究的目的是分析鼻咽癌颈淋巴结转移的影像学规律。方法:2003年7月至2003年11月,259例鼻咽癌患者在我院接受了放射治疗。所有患者治疗前接受横断面CT增强扫描,扫描范围是颅底至锁骨。由放射诊断医生和肿瘤放射治疗医生共同阅片,根据美国肿瘤放射治疗协会(RTOG)建议的分区准则,总结淋巴结在RTOG各区的分布,并运用χ2检验分析T分期和淋巴结转移之间的关系;进一步以舌骨和环状软骨下缘为界把颈部分成三个区组,分析淋巴结跳跃性转移的情况。结果:本组中218例(84.2%)发现有淋巴结转移,在各区的分布是Ⅰa0例,Ⅰb6例(2.8%),Ⅱa115例(52.8%),Ⅱb192例(88.1%),Ⅲ78例(35.8%),Ⅳ20例(9.2%),Ⅴ65例(29.9%),Ⅵ0例,咽后157例(72.0%),耳前2例(0.9%)。各区淋巴结转移比例和T分期之间没有明显相关性。5例(2.3%)发生跳跃性转移。结论:鼻咽癌淋巴结转移率高,Ⅱa、Ⅱb区和咽后最容易发生转移。淋巴结转移基本遵循由上到下,从近到远发展的规律,很少发生跳跃性转移,T分期和各区淋巴结的转移比例之间没有明显相关性。

BACKGROUND &OBJECTIVE: The application of intensity-modulated r ad iation therapy (IMRT) for nasopharyngeal carcinoma (NPC) requires a precise deli neation of the nodal area and nodal clinical target volume (CTV) on computed tom ography (CT) images,and the prerequisite is to find out the rules of CT-based d istribution of metastatic lymph nodes of NPC. This study was designed to analyze the rules of CT-based distribution of nodal involvements of NPC according to t he guidelines of nodal levels proposed by Radiation Therapy Oncology Group (RTOG ). METHODS: From Jul. 2003 to Nov.2003, 259 newly diagnosed NPC patients receive d radiotherapy at Fudan University Affiliated Cancer Hospital. All patients had transversal contrast enhanced CT scan from base of skull to clavicle before trea tment. Diagnostic radiologists and radiation oncologists together assessed the n odal distribution in each RTOG nodal level. Chi-square test was used to analyze the correlation between T stage and nodal metastasis rate. The neck was further divided into 3 regions by the verge of hyoid bone and the inferior border of cr icoid cartilage to assess leap metastasis of nodes. RESULTS: A total of 218 pati ents (84.2%)had nodal involvement. The distribution was as follow: 0 in level Ⅰa,6 (2.8%)in levelⅠb , 115 (52.8%)in level Ⅱa,192 (88.1%)in level Ⅱb, 78 (35.8%) in level Ⅲ, 20 (9.2%)in level Ⅳ, 65 (29.9%)in level Ⅴ, 0 in level Ⅵ,157 (72.0%)in retropharynx, and 2 (0.9%) at preauricular area . Leap metastases were found in only 5 patients (2.3%). No significant correl ation was found between T stage and nodal involvement. CONCLUSION: NPC has a hig h probability of nodal metastases, nodes in level Ⅱa,Ⅱb, and retropharynx are most likely to be involved. Nodes metastasized mostly from the upper to the lowe r level, and from the proximal to the distal part, with a very low leap metastas is rate. The relationship between T stage and nodal involvement has no statistic al significance.