Defining the Genomic Signature of the Parous Breast

It is widely accepted that a woman’s lifetime risk of developing breast cancer at menopause is reduced by early full term pregnancy and multiparity. This phenomenon is associated with the development and differentiation of the breast, which ultimately imprints a specific genomic profile in the mammary epithelium. In the present work we demonstrate that this profile represents a permanent signature that could be associated with the breast cancer risk reduction conferred by pregnancy. We have compared the gene expression profile of normal breast biopsies performed in 71 parous (P) and 42 nulliparous (NP) postmenopausal women. All samples were hybridized to Affymetrix HG_U133 Plus 2.0 oligonucleotide arrays. We compared the gene expression profile of normal breast core biopsies from 71 parous (women that had a full term pregnancy) and 42 nulliparous (women that never completed a pregnancy) postmenopausal women from Sweden. All samples were hybridized to Affymetrix HG_U133 Plus 2.0 oligonucleotide arrays.