Table 3.

Marker expression and mammographic density stratified by total breast size

Marker		Small total breast area			Large total breast area
		Category*			Category
		1	2	P-value	1	2	P-value
ERα	% density†	41.3	38.0	0.55	30.7	33.7	0.61
	Dense area#	29.5	29.1	0.92	34.6	39.7	0.53
	Number	63	16		59	19
ERβ	% density	41.3	39.5	0.71	29.9	36.3	0.24
	Dense area	28.9	29.7	0.82	34.1	41.2	0.34
	Number	50	29		60	18
PR	% density	39.0	43.3	0.36	27.1	33.3	0.19
	Dense area	28.8	29.8	0.78	28.3	40.0	0.05
	Number	45	36		32	45
HER2/neu	% density	41.7	39.8	0.71	30.4	33.5	0.51
	Dense area	30.3	28.6	0.65	35.2	37.6	0.71
	Number	55	24		49	28
Ki-67	% density	38.2	42.6	0.35	29.7	30.9	0.81
	Dense area	25.4	31.8	0.07	35.8	34.5	0.85
	Number	30	49		35	41
PCNA	% density	41.0	39.9	0.81	29.9	33.9	0.43
	Dense area	29.4	28.8	0.86	33.7	40.5	0.32
	Number	43	38		52	25

* Categories for ERα, ERβ, HER2/neu and PCNA; category 1 <10% staining, category 2 ≥ 10% staining. Categories for PR and Ki-67; category 1 = no staining, category 2 = any staining

^† Mean percent breast density

^# Mean dense area in cm²

Mean values and p-values calculated using general linear models adjusted for age at mammogram, BMI, ethnicity, HT use at mammogram, menopausal status, parity, age at first live birth, age at menarche and family history of breast cancer.

(ERα = estrogen receptor alpha; ERβ = estrogen receptor beta; PR = progesterone receptor; HER2/neu = Human Epidermal growth factor receptor2; PCNA = Proliferating Cell Nuclear Antigen; BMI = body mass index)