title: Breast size and breast cancer: a systematic review.
abstract: BACKGROUND
  There are many known breast cancer risk factors, but traditionally the list has not included breast size. The aim of this study was to synthesize the literature on breast size as a risk factor for breast carcinoma by examining studies addressing this question both directly and indirectly.
  
  
  METHODS
  A systematic review was performed searching MEDLINE from 1950 to November 2010, and updated again in February 2014. Literature was sought to assess the relationship between the following variables and breast cancer: 1) breast size; 2) breast reduction; 3) breast augmentation; and 4) prophylactic subcutaneous mastectomy. Findings were summarized and the levels of evidence were assessed.
  
  
  RESULTS
  50 papers were included in the systematic review. Increasing breast size appears to be a risk factor for breast cancer, but studies are limited by their retrospective nature, imperfect size measurement techniques and confounding variables. The evidence is stronger for risk reduction with breast reduction, including prophylactic subcutaneous mastectomy at the extreme. Generally the breast augmentation population has a lower risk of breast cancer than the general population, but it is unclear whether or not this is related to the bias of small breasts in this patient population and the presence of other confounders.
  
  
  CONCLUSIONS
  There is direct and indirect evidence that breast size is an important factor in the risk of developing breast cancer. Plastic surgeons are in a unique position to observe this effect. Well-designed prospective studies are required to further assess this risk factor.
authors.affiliation: Division of Plastic and Reconstructive Surgery, University of Toronto, Canada.
authors.forename: L A
authors.initials: LA
authors.lastname: Jansen
authors.affiliation: Division of Plastic and Reconstructive Surgery, University of Toronto, Canada.
authors.forename: R M
authors.initials: RM
authors.lastname: Backstein
authors.affiliation: Division of Plastic and Reconstructive Surgery, University of Toronto, Canada. Electronic address: drbrown@torontoplasticsurgery.com.
authors.forename: M H
authors.initials: MH
authors.lastname: Brown
mesh_terms: D001940:Breast / Q000033:anatomy & histology* / Q000601:surgery; D001943:Breast Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D016462:Mammaplasty; D015414:Mastectomy, Subcutaneous; D009929:Organ Size; D012307:Risk Factors
keywords: Breast cancer; Breast size; Epidemiology; Risk reduction