Table 3.

Logistic regression analysis of the risk factors for lymph node metastasis in cohort N.

Factors	Univariate analysis			Multivariate analysis
	OR	95%CI	P	OR	95%CI	P
Age
≤56	Reference			Reference
>56	0.73	0.67-0.79	<0.001	0.64	0.58-0.70	<0.001
Race
White	Reference			Reference
Black	1.25	1.13-1.37	<0.001	1.15	1.04-1.28	0.007
American Indian/  Alaska Native	1.18	0.81-1.69	0.374	1.21	0.81-1.79	0.337
Asian or Pacific Islander	1.05	0.94-1.18	0.354	1.06	0.94-1.19	0.373
Sex
Male	Reference			Reference
Female	0.75	0.71-0.79	<0.001	0.91	0.86-0.97	0.004
Histology
Adenocarcinomas	Reference			Reference
Squamous cell carcinoma	1.25	1.18-1.33	<0.001	0.82	0.77-0.88	<0.001
Large cell carcinoma	1.95	1.45-2.61	<0.001	1.06	0.76-1.49	0.718
Others	0.53	0.47-0.59	<0.001	0.71	0.62-0.80	<0.001
T-stage
T1a	Reference			Reference
T1b	1.85	1.68-2.03	<0.001	1.04	0.91-1.19	0.578
T2a	3.54	3.26-3.83	<0.001	1.50	1.33-1.70	<0.001
T2b	7.37	6.66-8.16	<0.001	2.56	2.20-2.97	<0.001
Marital status
Married	Reference			Reference
Single	0.98	0.90-1.06	0.608	0.86	0.79-0.95	0.002
Divorced	1.02	0.93-1.11	0.720	0.99	0.90-1.09	0.882
Widowed	0.86	0.80-0.93	<0.001	0.87	0.79-0.94	0.001
Tumor size
1-19	Reference			Reference
20-29	1.93	1.76-2.11	<0.001	1.67	1.48-1.89	<0.001
>29	4.85	4.47-5.25	<0.001	2.67	2.35-3.04	<0.001
Grade
Well differentiated; Grade I	Reference			Reference
Moderately differentiated;  Grade II	2.89	2.61-3.21	<0.001	2.48	2.22-2.77	<0.001
Poorly differentiated;  Grade III	5.09	4.59-5.65	<0.001	3.73	3.34-4.17	<0.001
Undifferentiated; anaplastic;  Grade IV	5.10	3.95-6.57	<0.001	3.49	2.62-4.64	<0.001
Laterality
Left	Reference			Reference
Right	0.96	0.90-1.01	0.128	0.96	0.91-1.02	0.214