Table 2.

Patient and tumor characteristics of Luminal B invasive breast cancer cases

	N	Luminal B (HER2+)						P‐valuea
		ER+/PR+		ER+/PR−		ER−/PR+		ER+/PR+:	ER+/PR+:	ER+/PR−:
		N	%	N	%	N	%	ER+/PR−	ER−/PR+	ER−/PR+
Total	16,354	11,391		4491		472
Age at diagnosis								<0.0001	0.7842	<0.0001
<50	4621	3518	30.9	950	21.2	153	32.4
50–64	6631	4431	38.9	2016	44.9	184	39.0
65–74	2886	1951	17.1	855	19.0	80	16.9
≥75	2216	1491	13.1	670	14.9	55	11.7
Race/ethnicity								0.3661	<0.0001	<0.0001
NH white	10,793	7545	66.2	2970	66.1	278	58.9
NH black	1918	1306	11.5	555	12.4	57	12.1
Asian/Pacific Islander	1491	1038	9.1	400	8.9	53	11.2
Am. Indian/Alaska Native	105	63	0.6	30	0.7	12	2.5
Hispanic	1921	1352	11.9	503	11.2	66	14.0
Unknown	126	87	0.8	33	0.7	6	1.3
AJCC stage								<0.0001	<0.0001	0.003
0–I	6383	4534	39.8	1710	37.9	139	29.2
II	5792	4073	35.8	1536	34.2	183	38.8
III	2463	1697	14.9	676	15.1	90	19.1
IV	1260	781	6.9	437	9.7	42	8.9
Unknown	456	306	2.7	132	2.9	18	3.8
Tumor size								<0.0001	0.1152	0.7848
≤0.5 cm	1348	861	7.6	443	9.9	44	9.3
>0.5 cm	14,178	9983	87.6	3800	84.6	395	83.7
Unknown	828	547	4.8	248	5.5	33	7.0
Poverty index								0.1446	0.6807	0.3295
Q1	3648	2514	22.1	1025	22.8	109	23.1
Q2	3717	2585	22.7	1030	22.9	102	21.6
Q3	3814	2635	23.1	1078	24.0	101	21.4
Q4	5172	3654	32.1	1358	30.2	160	33.9
Unknown	3	3	0.0	0	0.0	0	0.0

Summary of clinical and demographic characteristics of hormone receptor‐positive (HR+), HER2+ Luminal B breast cancers in women with invasive breast cancer: Surveillance, Epidemiology and End Results 18, 2010–2012. NH, non‐Hispanic; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.

^a P‐value calculations do not include unknown values.