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Table 1 Univariable analyses of factors related to level IB LNs metastases at diagnosis in 1438 patients

From: Investigation of the feasibility of elective irradiation to neck level Ib using intensity-modulated radiotherapy for patients with nasopharyngeal carcinoma: a retrospective analysis

Variable Metastasis to level Ib LNs at diagnosis, N (%) *P
(−), n = 1398 (+), n = 40
Sex    
Male 1052 (75.3) 33 (82.5) .294
Female 346 (24.7) 7 (17.5)
Age    
<50 years 950 (68.0) 23 (57.5) .163
≥50 years 448 (32.0) 17 (42.5)
Histologic type    
Keratinizing squamous cell carcinoma 5 (0.4) 0 1.000
Nonkeratinizing carcinoma 1393 (99.6) 40 (100.0)
T stage   
T1 247 (17.7) 5 (12.5) .537
T2 207 (14.8) 6 (15.0)
T3 679 (48.6) 18 (45.0)
T4 265 (19.0) 11 (27.5)
T classification    
T1-3 1133 (81.0) 29 (72.5) .176
T4 265 (19.0) 11 (27.5)
Oropharynx involvement    
(−) 1291 (92.3) 31 (77.5) .001
(+) 107 (7.7) 9 (22.5)
Nasal cavity involvement    
(−) 918 (65.7) 22 (55.0) .162
(+) 480 (34.3) 18 (45.0)
N classification    
N0 235 (16.8) 0 <.001
N1 823 (58.9) 19 (47.5)
N2 216 (15.5) 13 (32.5)
N3 124 (8.9) 8 (20.1)
Positive RLNs    
(−) 387 (27.7) 3 (7.5) .005
(+) 1011 (72.3) 37 (92.5)
Positive CLNs    
(−) 570 (40.8) 4 (10.0) <.001
(+) 828 (59.2) 36 (90.0)
LN necrosis    
(−) 1054 (75.4) 22 (55.0) <.001
(+) 344 (24.6) 18 (45.0)
LNs with ES    
(−) 1051 (75.2) 26 (65.0) .143
(+) 347 (24.8) 14 (35.0)
DLN-IIa ≥30 mm or level IIa LNs with ES   
(−) 1247 (89.2) 34 (85.0) .435
(+) 151 (10.8) 6 (15.0)
DLN-IIa ≥20 mm or level IIa LNs with ES   
(−) 1113 (79.6) 19 (47.5) <.001
(+) 285 (20.4) 21 (52.5)
MAD of LNs ≥30 mm    
(−) 1196 (85.6) 26 (65.0) <.001
(+) 202 (14.4) 14 (35.0)
Positive bilateral CLNs    
(−) 1121 (80.2) 20 (50.0) <.001
(+) 277 (19.8) 20 (50.0)  
Positive CLNs at supraclavicular fossa   
(−) 1318 (94.3) 21 (80.0) <.001
(+) 80 (5.7) 8 (20.0)
  1. Abbreviations: LNs, lymph nodes; WHO, World Health Organization; RLNs, retropharyngeal lymph nodes; CLNs, cervical lymph nodes; LNs, lymph nodes; DLN-IIa, greatest dimension of level IIa lymph nodes; MAD, maximal axial diameter; ES, extra-capsular spread
  2. *P-values were calculated using an unadjusted chi-square test (or Fisher’s exact test, if indicated)