title: Established breast cancer risk factors and risk of intrinsic tumor subtypes.
abstract: Breast cancer is a heterogeneous disease with multiple intrinsic tumor subtypes. These subtypes vary in tumor gene expression and phenotype, and are most commonly grouped into four major subtypes: luminal A, luminal B, HER2-overexpressing and triple negative (or basal-like). A growing number of studies have evaluated the relationship between established breast cancer risk factors and risk of one or more intrinsic tumor subtypes. We conducted a systematic review of 38 studies to synthesize their results and identify areas requiring more research. Taken together, published studies suggest that most established breast cancer risk factors reflect risk factors for the luminal A subtype of breast cancer, and some breast cancer risk factors may be differentially associated with other intrinsic tumor subtypes. Future breast cancer research will need to consider etiologic differences across subtypes and design studies focused on understanding the etiology and prevention of less common tumor subtypes.
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Channing Division of Network Medicine, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA 02115, USA. Electronic address: mollie.barnard@mail.harvard.edu.
authors.forename: Mollie E
authors.initials: ME
authors.lastname: Barnard
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Channing Division of Network Medicine, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Boeke
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Channing Division of Network Medicine, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Rulla M
authors.initials: RM
authors.lastname: Tamimi
mesh_terms: D000293:Adolescent; D001943:Breast Neoplasms / Q000145:classification / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008019:Life Style; D008875:Middle Aged; D012307:Risk Factors
keywords: Breast cancer; HER2; Luminal; Risk factor; Subtype; Triple negative