Patterns of lymph node metastasis from nasopharyngeal carcinoma based on the 2013 updated consensus guidelines for neck node levels XiaoShen Wang*, ChaoSu Hu*, HongMei Ying*, XiaYun He*, ZhengRong Zhou†, JianHui Ding† * Department of Radiation Oncology and † Department of Diagnostic Radiology, Fudan University Shanghai Cancer Center. Department of Oncology, Shanghai Medical College of Fudan University, Shanghai, 200032

objective WANG XS, et al. Fudan University Shanghai Cancer Center To explore the patterns of node spread from NPC based on the 2013 updated guidelines. WANG XS, et al. Fudan University Shanghai Cancer Center

Methods Patients with NPC were required to undergo MRI. The scan range extended from 2cm above the anteroir clinoid process to the inferior margin of the sternal end of the clavicle. All MR images were evaluated by the multi-disciplinary treatment group of NPC. WANG XS, et al. Fudan University Shanghai Cancer Center

Results From January 2010 to January 2013, 3100 cases of newly diagnosed NPC were enrolled in the study. A total of 2679 (86.4%）cases had involved lymph nodes. WANG XS, et al. Fudan University Shanghai Cancer Center

WANG XS, et al. Fudan University Shanghai Cancer Center Detailed distribution of the 2679 cases with involved nodes Level No. of patients percentage (%) Ia 0 0 Ib 115 4.3 IIa 1798 67.1 IIb 2341 87.4 III 1184 44.2 IVa 350 13.1 IVb 28 1.0 Va 576 21.5 Vb 419 15.6 Vc 49 1.8 VIa 0 0 VIb 0 0 VIIa 2012 75.1 VIIb 178 6.6 VIII 53 2.0 IX 2 0.07 Xa 2 0.07 Xb 10 0.4 WANG XS, et al. Fudan University Shanghai Cancer Center

Retropharyngeal lymph node 2012（75.1%）had RPLN. Only 6（0.2%）were at the medial group, accompanied with lateral RPLN and other node metastasis. Only one medial RPLN can be identified in a patient, whereas the number of the lateral RPLNs per affected side varied between 1 and 4. WANG XS, et al. Fudan University Shanghai Cancer Center

The Upper border of levelⅡnode upper border Number(%) level Ⅱb level Ⅱa Upper border of C1 115 (4.9%) 0 Half of C1 492（21.0％） 0 Below C1 1734（74.1％） 1798 (100%) Total 2341 1798 WANG XS, et al. Fudan University Shanghai Cancer Center

Illustration of level II node beyond the consensus guidelines WANG XS, et al. Fudan University Shanghai Cancer Center

Node beyond level V ① 35 nodes were beyond the level V range, located at ①. WANG XS, et al. Fudan University Shanghai Cancer Center

Nodes beyond the updated guidelines WANG XS, et al. Fudan University Shanghai Cancer Center

Conclusions: This is the first description of nodal spread patterns based on the updated consensus guidelines. Invovelment of RPLNs were mainly located at the lateral group, the medial group was rarely seen. Nodal involvement spread in an orderly pattern in NPC. The upper border of level II should be skull base. The level V borders recommended in this consensus guidelines can not fully cover all lymphadenopathies for NPC. WANG XS, et al. Fudan University Shanghai Cancer Center