Table IV. Cox multivariate model of the effects of clinical and demographic covariates on survival.

	Full study cohort 2930 patients			Pathologically confirmed LN 999 patients
	HR	95% CI	P-value	HR	95% CI	P-value
Age at diagnosis	1.02	1.01–1.03	<0.001	1.02	1.01–1.03	<0.001
Female sex	0.88	0.80–0.96	0.006	0.79	0.67–0.94	0.007
African American race	1.20	1.01–1.41	0.033	0.99	0.71–1.37	0.946
Hispanic ethnicity	0.99	0.88–1.11	0.827	1.04	0.84–1.29	0.710
Radiation	0.78	0.70–0.87	<0.001	0.65	0.54–0.79	<0.001
Surgery
Total vs. Local	0.99	0.84–1.17	0.898	0.87	0.64–1.18	0.369
Radical vs. Local	0.91	0.75–1.11	0.352	0.85	0.61–1.20	0.354
Era (1997–2004 vs. 1988–96)	0.93	0.85–1.02	0.115	0.82	0.70–0.97	0.022
Tumor grade
II vs. I	1.27	1.11–1.44	<0.001	1.28	0.99–1.66	0.064
III vs. I	1.84	1.61–2.10	<0.001	1.71	1.32–2.22	<0.001
IV vs. I	2.00	1.42–2.82	<0.001	2.13	1.27–3.57	0.004
Tumor extent (T stage)
T2 vs. T1	1.21	1.05–1.39	0.008	0.92	0.64–1.31	0.626
T3 vs. T1	2.29	2.02–2.59	<0.001	2.13	1.55–2.91	<0.001
T4 vs. T1	3.81	3.14–4.62	<0.001	3.23	1.97–5.31	<0.001
LN involvement (N stage)	1.80	1.37–2.37	<0.001	2.84	1.99–4.04	<0.001