. Author manuscript; available in PMC: 2013 Jul 10.

Published in final edited form as: Breast Cancer Res Treat. 2011 Aug 30;131(1):267–275. doi: 10.1007/s10549-011-1727-4

Table 2.

Histology of dense and non-dense areas of the breast of healthy women (N = 59 women)

Breast tissue type	Dense tissue	Dense tissue	Non-dense tissue	Non-dense tissue	Difference between dense and non-dense	Difference between dense and non-dense
	Mean area (mm²)	Proportion (%)^a	Mean area (mm²)	Proportion (%)^a	Mean area (mm²)	Proportion (%)^a
Epithelium	1.21 (1.43)	5.6 (5.0)	0.14 (0.36)	0.7 (1.8)	1.07 (1.33)^b	4.8 (4.9)^b
Stroma	12.07 (6.17)	64.7 (17.7)	2.92 (3.57)	18.6 (14.5)	9.15 (5.90)^b	46.1 (20.6)^b
Fat	5.51 (4.27)	29.7 (18.5)	11.50 (6.0)	80.6 (15.8)	−5.99 (7.09)^b	−50.9 (21.5)^b
Epithelium and stroma combined	13.28 (7.10)	70.3 (18.5)	3.06 (3.86)	19.4 (15.8)	10.22 (6.65)^b	50.9 (21.5)^b

Numbers in parentheses represent standard deviation

Proportion refers to the ratio of the area of the specific tissue type to the total area of breast tissue on the slide

Pvalues for within woman difference between dense and non-dense <0.0001