title: Mammary stem cells and parity-induced breast cancer protection- new insights.
abstract: Parity (childbearing) significantly decreases a woman's risk of breast cancer and the protective effect is greater if the woman is younger and has more children. The mechanism/s of parity-induced protection are not known. Although several factors are postulated to play a role, we discuss how a reduction in the number of mammary stem cells (MaSCs) may lead to a reduction in breast cancer risk in parous women. Firstly we review the epidemiology linking childbearing to reduced breast cancer risk and discuss how additional births, a young age at first full term birth, and breastfeeding impact the protection. We then detail the mouse and human studies implicating MaSC in parity induced protection and the in-vivo work being performed in mice to directly investigate the effect of parity on MaSC. Finally we discuss the transplant and lineage tracing experiments assessing MaSC activity according to parity and the need to define if MaSC are indeed more carcinogen sensitive than mature mammary epithelial cells. Continuing and future studies attempting to define the parity induced mechanisms will aid in the development of preventative therapies.
authors.affiliation: Metastasis Research Laboratory, Peter MacCallum Cancer Centre, 7 St Andrews Place, East Melbourne 3002, Australia; Department of Anatomy and Developmental Biology, Monash University Clayton, Wellington Rd 3800, Australia.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Dall
authors.affiliation: Department of Anatomy and Developmental Biology, Monash University Clayton, Wellington Rd 3800, Australia.
authors.forename: Gail
authors.initials: G
authors.lastname: Risbridger
authors.affiliation: Metastasis Research Laboratory, Peter MacCallum Cancer Centre, 7 St Andrews Place, East Melbourne 3002, Australia; Department of Anatomy and Developmental Biology, Monash University Clayton, Wellington Rd 3800, Australia; The Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia. Electronic address: Kara.britt@petermac.org.
authors.forename: Kara
authors.initials: K
authors.lastname: Britt
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism / Q000517:prevention & control*; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D013234:Stem Cells / Q000378:metabolism*
keywords: Breast cancer; Mammary stem cells; Parity