Lund E, et al. - In view of a large body of evidence reporting long-lasting protective effect of each full-term pregnancy (FTP) on the development of breast cancer (BC) later in life, a phenomenon that could be related to both hormonal and immunological changes during pregnancies, researchers examined pregnancy-related variations in peripheral blood gene expression profiles between healthy women and women diagnosed with BC in a prospective design. They found that BC cases and healthy controls had markedly different gene expression and enrichment profiles of immunologic gene sets. This finding was indicative of an important protective impact of the immune system on BC risk. Women with six children vs nulliparous showed 48% reduction in the incidence of BC.