Study of level Ⅴmetastasis of nasopharyngeal carcinoma based on 2013 updated consensus guidelines of the neck node levels / 中华放射肿瘤学杂志

ABSTRACT

Objective:According to 2013 updated consensus guidelines of neck node levels, the distribution characteristics of cervical lymph nodes of nasopharyngeal carcinoma (NPC) were analyzed, aiming to provide preliminary reference for the clinical target volume (CTV) delineation of level Ⅴ in NPC.Methods:A total of 1110 patients pathologically diagnosed with NPC from 2012 to 2020 were retrospectively recruited for further analysis. All patients’ MRI and contrast-enhanced CT simulation scan imageswere retrospectively reviewed, metastatic lymph nodes were mapped using the 2013 International Consensus Guidelines. Then, the correlation between Ⅴa, Ⅴb and Ⅴc metastatic lymph nodes and other lymph nodes was analyzed. An NPC case diagnosed with T 1N 0M 0 was selected as the baseline standard for the normal anatomical structure and proportion of Ⅴc area. The metastatic lymph nodes in Vc were delineated on the CT simulation scan image of sample case, and the distribution characteristics of the metastatic lymph nodes inⅤc were analyzed. Results:Among the 1110 patients, 1004(90.5%) patients had lymph node metastases. The most common area of metastatic lymph node levels were level Ⅶa (74.7%) and level Ⅱb(70.7%), and the skip metastasis of lymph nodes was rare (1.0%). The multivariate analysis showed lymph node metastasis in level Va was correlated with levels Ⅱb, Ⅲ, Ⅳa, Ⅴb, and Ⅷ region ( P=0.010, 0.001, 0.001, 0.001, 0.037). Lymph node metastasis in level Ⅴb was correlated with levels Ⅲ, Ⅳa, Ⅴa and Ⅴc region ( P=0.006, 0.001, 0.001, 0.001). Lymph node metastasis in level Ⅴc was correlated with levels Ⅳb and Ⅴb region ( P=0.008, 0.001). There were 28 cases of lymph node metastasis in levelⅤc. A total of 38 metastatic lymph nodes were counted in level Vc. Among them, 33(86.8%) lymph nodes were located in the medial of the omohyoid muscle (Ⅴc-1 region), and 5(13.2%) were located in the lateral of the omohyoid muscle (Ⅴc-2 region). Conclusions:This study reflects the principle of individualized CTV delineation, which is based on the levels of nodal spread in NPC patients. When correlation is observed among different level V, V should be delineated as the moderate risk lymphatic drainage (CTV n2). It is recommended to individualized delineate level Vc when the CTV n2 covers Vc. The Ⅴc-2 region should be delineated as CTV n2 only when there is nodal spread in the ipsilateral Ⅴc-1 region.