title: Tissue composition of mammographically dense and non-dense breast tissue.
abstract: Mammographic density is a strong risk factor for breast cancer but its underlying biology in healthy women is not well-defined. Using a novel collection of core biopsies from mammographically dense versus non-dense regions of the breasts of healthy women, we examined histologic and molecular differences between these two tissue types. Eligible participants were 40 + years, had a screening mammogram and no prior breast cancer or current endocrine therapy. Mammograms were used to identify dense and non-dense regions and ultrasound-guided core biopsies were performed to obtain tissue from these regions. Quantitative assessment of epithelium, stroma, and fat was performed on dense and non-dense cores. Molecular markers including Ki-67, estrogen receptor (ER) and progesterone receptor (PR) were also assessed for participants who had >0% epithelial area in both dense and non-dense tissue. Signed rank test was used to assess within woman differences in epithelium, stroma and fat between dense and non-dense tissue. Differences in molecular markers (Ki-67, ER, and PR) were analyzed using generalized linear models, adjusting for total epithelial area. Fifty-nine women, mean age 51 years (range: 40-82), were eligible for analyses. Dense tissue was comprised of greater mean areas of epithelium and stroma (1.1 and 9.2 mm(2) more, respectively) but less fat (6.0 mm(2) less) than non-dense tissue. There were no statistically significant differences in relative expression of Ki-67 (P = 0.82), ER (P = 0.09), or PR (P = 0.96) between dense and non-dense tissue. Consistent with prior reports, we found that mammographically dense areas of the breast differ histologically from non-dense areas, reflected in greater proportions of epithelium and stroma and lesser proportions of fat in the dense compared to non-dense breast tissue. Studies of both epithelial and stromal components are important in understanding the association between mammographic density and breast cancer risk.
authors.affiliation: Department of Medicine, Mayo Clinic College of Medicine, Charlton 6-239, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Karthik
authors.initials: K
authors.lastname: Ghosh
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Brandt
authors.forename: Carol
authors.initials: C
authors.lastname: Reynolds
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Scott
authors.forename: V S
authors.initials: VS
authors.lastname: Pankratz
authors.forename: Darren L
authors.initials: DL
authors.lastname: Riehle
authors.forename: Wilma L
authors.initials: WL
authors.lastname: Lingle
authors.forename: Tonye
authors.initials: T
authors.lastname: Odogwu
authors.forename: Derek C
authors.initials: DC
authors.lastname: Radisky
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Visscher
authors.forename: James N
authors.initials: JN
authors.lastname: Ingle
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Hartmann
authors.forename: Celine M
authors.initials: CM
authors.lastname: Vachon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001940:Breast / Q000502:physiology*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D004848:Epithelium / Q000502:physiology; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008327:Mammography; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
chemical_list: D019394:Ki-67 Antigen; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone