title: Evidence that breast tissue stiffness is associated with risk of breast cancer.
abstract: BACKGROUND
  Evidence from animal models shows that tissue stiffness increases the invasion and progression of cancers, including mammary cancer. We here use measurements of the volume and the projected area of the compressed breast during mammography to derive estimates of breast tissue stiffness and examine the relationship of stiffness to risk of breast cancer.
  
  
  METHODS
  Mammograms were used to measure the volume and projected areas of total and radiologically dense breast tissue in the unaffected breasts of 362 women with newly diagnosed breast cancer (cases) and 656 women of the same age who did not have breast cancer (controls). Measures of breast tissue volume and the projected area of the compressed breast during mammography were used to calculate the deformation of the breast during compression and, with the recorded compression force, to estimate the stiffness of breast tissue. Stiffness was compared in cases and controls, and associations with breast cancer risk examined after adjustment for other risk factors.
  
  
  RESULTS
  After adjustment for percent mammographic density by area measurements, and other risk factors, our estimate of breast tissue stiffness was significantly associated with breast cancer (odds ratio = 1.21, 95% confidence interval = 1.03, 1.43, p = 0.02) and improved breast cancer risk prediction in models with percent mammographic density, by both area and volume measurements.
  
  
  CONCLUSIONS
  An estimate of breast tissue stiffness was associated with breast cancer risk and improved risk prediction based on mammographic measures and other risk factors. Stiffness may provide an additional mechanism by which breast tissue composition is associated with risk of breast cancer and merits examination using more direct methods of measurement.
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada.
authors.forename: Norman F
authors.initials: NF
authors.lastname: Boyd
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada.
authors.forename: Olga
authors.initials: O
authors.lastname: Melnichouk
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada.
authors.forename: Ella
authors.initials: E
authors.lastname: Huszti
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Martin
authors.affiliation: Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Anoma
authors.initials: A
authors.lastname: Gunasekara
authors.affiliation: Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Gord
authors.initials: G
authors.lastname: Mawdsley
authors.affiliation: Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Yaffe
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada.
authors.forename: Salomon
authors.initials: S
authors.lastname: Minkin
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001940:Breast / Q000166:cytology* / Q000473:pathology*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D008327:Mammography; D055595:Mechanical Phenomena; D008875:Middle Aged; D009929:Organ Size; D012306:Risk