Genomic signature of parity in the breast of premenopausal women

Full-term pregnancy (FTP) at an early age confers long-term protection against breast cancer, in this study, we evaluated gene expression changes induced by parity in the breast of premenopausal women. Gene expression profiling of normal breast tissue from 30 nulliparous (NP) and 79 parous (P) premenopausal volunteers were performed using Affymetrix microarrays. In addition to a discovery/validation analysis, we conducted analysis of gene expression differences in P vs. NP women as a function of time since last FTP. We compared the gene expression profile of normal breast core biopsies from 79 parous (women that had a full term pregnancy) and 30 nulliparous (women that never completed a pregnancy) premenopausal women from Sweden. All samples were hybridized to Affymetrix HG_U133 Plus 2.0 oligonucleotide arrays.