Height, adiposity and body fat distribution and breast density in young women.
BACKGROUND
Breast density is one of the strongest risk factors for breast cancer, but determinants of breast density in young women remain largely unknown.


METHODS
Associations of height, adiposity and body fat distribution with percentage dense breast volume (%DBV) and absolute dense breast volume (ADBV) were evaluated in a cross-sectional study of 174 healthy women, 25 to 29 years old. Adiposity and body fat distribution were measured by anthropometry and dual-energy X-ray absorptiometry (DXA), while %DBV and ADBV were measured by magnetic resonance imaging. Associations were evaluated using linear mixed-effects models. All tests of statistical significance are two-sided.


RESULTS
Height was significantly positively associated with %DBV but not ADBV; for each standard deviation (SD) increase in height, %DBV increased by 18.7% in adjusted models. In contrast, all measures of adiposity and body fat distribution were significantly inversely associated with %DBV; a SD increase in body mass index (BMI), percentage fat mass, waist circumference and the android:gynoid fat mass ratio (A:G ratio) was each associated significantly with a 44.4 to 47.0% decrease in %DBV after adjustment for childhood BMI and other covariates. Although associations were weaker than for %DBV, all measures of adiposity and body fat distribution also were significantly inversely associated with ADBV before adjustment for childhood BMI. After adjustment for childhood BMI, however, only the DXA measures of percentage fat mass and A:G ratio remained significant; a SD increase in each was associated with a 13.8 to 19.6% decrease in ADBV. In mutually adjusted analysis, the percentage fat mass and the A:G ratio remained significantly inversely associated with %DBV, but only the A:G ratio was significantly associated with ADBV; a SD increase in the A:G ratio was associated with an 18.5% decrease in ADBV.


CONCLUSIONS
Total adiposity and body fat distribution are independently inversely associated with %DBV, whereas in mutually adjusted analysis only body fat distribution (A:G ratio) remained significantly inversely associated with ADBV in young women. Research is needed to identify biological mechanisms underlying these associations.
Joanne F
JF
Dorgan
Catherine
C
Klifa
John A
JA
Shepherd
Brian L
BL
Egleston
Peter O
PO
Kwiterovich
John H
JH
Himes
Kelley
K
Gabriel
Linda
L
Horn
Linda G
LG
Snetselaar
Victor J
VJ
Stevens
Bruce A
BA
Barton
Alan M
AM
Robson
Norman L
NL
Lasser
Snehal
S
Deshmukh
Nola M
NM
Hylton
D015502:Absorptiometry, Photon; D050154:Adiposity; D000328:Adult; D000367:Age Factors; D050218:Body Fat Distribution; D001827:Body Height; D001837:Body Weights and Measures; D001943:Breast Neoplasms / Q000473:pathology; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D042361:Mammary Glands, Human; D012307:Risk Factors