Table 1.

Selected characteristics of study sample

Characteristic	Gene expressiona		Methylationb
	N	[%]	N	[%]
Total	959	[100]	767	[100]
Race
nH white	592	[85.6]	471	[78.6]
nH black	100	[14.5]	128	[21.4]
Age (years)
>/=50	682	[73.3]	477	[71.3]
<50	248	[26.7]	192	[28.7]
Menopausal status
Post	653	[76.1]	497	[75]
Pre	205	[23.9]	165	[25]
Stage
I	160	[17.3]	126	[17.4]
II	536	[58]	402	[55.4]
III	213	[23.1]	188	[25.9]
IV	15	[1.6]	10	[1.4]
HR expression
ER+/PR+	585	[65.6]	452	[65.8]
ER+/PR−	104	[11.7]	78	[11.4]
ER−/PR+	14	[3.3]	15	[2.2]
ER−/PR−	189	[21.2]	142	[20.7]
Intrinsic subtype
Luminal A	219	[45]	108	[51.4]
Luminal B	116	[23.9]	43	[20.5]
HER2+/HR−	55	[11.3]	14	[6.7]
Basal-like	88	[18.1]	40	[19]
Normal-like	8	[1.7]	5	[2.4]
Combined TN status endpoint
Luminal A	472	[74.8]	398	[76.7]
Triple negative	159	[25.2]	121	[23.3]

nH non-Hispanic, HR hormone receptor, ER/PR estrogen and progesterone receptor, HER2 human epidermal growth factor receptor-2

To demonstrate the basic distribution of study covariates:

^aAn expression ‘flag’ marker (KCNK2) with no missing values is used (mRNA Expression z-scores, RNA Seq V2 RSEM)

^bA methylation ‘flag’ marker (cg21415530, KCNK9) with no missing values is used