Abstract CN13-02: Breast tissue composition and risk of breast cancer

Susceptibility to breast carcinogens is greatest before the age of 20 years. We have used magnetic resonance (MR) to measure the water content of the breast in young women, and have identified factors associated with variations in breast water. Breast water, like mammographic density, reflects fibro-glandular breast tissue, which is strongly associated with breast cancer risk in middle aged and older women.

We recruited 400 young women aged 15-30 years and their mothers, measured breast water and fat in daughters using (MR), and obtained anthropometric and other data. Mothers provided mammograms (n=365) and a random sample (n=100) also had breast MR.

Percent water by MR in daughters (median=44.8%) was greater than in mothers (median=27.8%) (P<0.0001), and was greater in daughters aged 15-19 years (n=199; median=49%) than in those aged 20-30 years (n=201; median=41%). Percent water in daughters was correlated with both breast water (n=100 pairs; r=0.28; p=0.005), and percent mammographic density in mothers (n=356 pairs; r=0.25, p<0.0001). Percent water in daughters was independently associated with their age (p=0.04) and weight (p<0.0001) (both inversely), and with their height (p<0.0001) and percent density in their mothers’ mammogram (p<0.0001) (both positively).

Percent breast water was greatest at ages when susceptibility to breast carcinogens is also greatest. The distribution of breast water according to age was consistent with a model in which mammographic density in mid-life is in part the result of genetic influences and growth and development in early life that determine initial breast tissue composition.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):CN13-02.