Table 2. Multivariate analysis of prognostic factors among ER negative patients with pure IDC and IDC-DCIS.

Characteristics	BCSS				OS
	HR	95% CI	P		HR	95% CI	P
Year of diagnosis	0.987	0.976–0.998	0.023		0.987	0.977–0.997	0.010
Age
≤60 vs. >60 years	0.729	0.681–0.780	<0.001		0.509	0.481–0.539	<0.001
Race			<0.001				<0.001
Black vs. White	1.306	1.203–1.418	<0.001		1.241	1.156–1.333	<0.001
Asian or Indian vs. White	0.708	0.593–0.846	0.001		0.653	0.559–0.764	<0.001
Histologic grade			<0.001				0.047
I vs. III	0.330	0.157–0.695	0.004		0.675	0.472–0.964	0.030
II vs. III	0.828	0.739–0.928	0.001		0.929	0.853–1.012	0.092
T stage			<0.001				<0.001
T1 vs. T4	0.216	0.185–0.253	<0.001		0.234	0.203–0.269	<0.001
T2 vs. T4	0.435	0.377–0.502	<0.001		0.436	0.382–0.498	<0.001
T3 vs. T4	0.742	0.633–0.870	<0.001		0.743	0.641–0.862	<0.001
N stage			<0.001				<0.001
N0 vs. N3	0.195	0.171–0.222	<0.001		0.244	0.216–0.275	<0.001
N1 vs. N3	0.411	0.363–0.466	<0.001		0.435	0.387–0.489	<0.001
N2 vs. N3	0.720	0.627–0.826	<0.001		0.757	0.665–0.862	<0.001
Existence of DCIS component
IDC-DCIS vs. pure IDC	1.152	1.081–1.228	<0.001		1.089	1.033–1.148	0.002
Surgery
BCS vs. mastectomy	0.932	0.861–1.009	0.082		0.942	0.881–1.007	0.081
Radiation
Yes vs. none or unknown	0.937	0.869–1.010	0.088		0.867	0.813–0.924	<0.001
Chemotherapy
Yes vs. none or unknown	0.610	0.561–0.664	<0.001		0.453	0.425–0.483	<0.001
PR status
Positive vs. negative	0.744	0.573–0.968	0.027		0.794	0.645–0.978	0.030

IDC, invasive ductal breast cancer; DCIS, ductal carcinoma in situ; BCSS, breast cancer-specific survival; OS, overall survival; HR, hazard ratio; CI, confidence interval.