title: Change of mammographic density predicts the risk of contralateral breast cancer--a case-control study.
abstract: BACKGROUND
  Mammographic density is a strong risk factor for breast cancer, but it is unknown whether density at first breast cancer diagnosis and changes during follow-up influences risk of non-simultaneous contralateral breast cancer (CBC).
  
  
  METHODS
  We collected mammograms for CBC-patients (cases, N = 211) and unilateral breast cancer patients (controls, N = 211), individually matched on age and calendar period of first breast cancer diagnosis, type of adjuvant therapy and length of follow-up (mean follow-up time: 8.25 years). The odds of CBC as a function of changes of density during follow-up were investigated using conditional logistic regression, adjusting for non-dense area at diagnosis.
  
  
  RESULTS
  Patients who experienced ≥10% absolute decrease in percent density had a 55% decreased odds of CBC (OR = 0.45 95% CI: 0.24 to 0.84) relative to patients who had little or no change in density from baseline to first follow-up mammogram (mean = 1.6 (SD = 0.6) years after diagnosis), whereas among those who experienced an absolute increase in percent density we could not detect any effect on the odds of CBC (OR = 0.83 95% CI: 0.24 to 2.87).
  
  
  CONCLUSIONS
  Decrease of mammographic density within the first two years after first diagnosis is associated with a significantly reduced risk of CBC, this potential new risk predictor can thus contribute to decision-making in follow-up strategies and treatment.
authors.forename: Maria E C
authors.initials: ME
authors.lastname: Sandberg
authors.forename: Jingmei
authors.initials: J
authors.lastname: Li
authors.forename: Per
authors.initials: P
authors.lastname: Hall
authors.forename: Mikael
authors.initials: M
authors.lastname: Hartman
authors.forename: Isabel
authors.initials: I
authors.lastname: dos-Santos-Silva
authors.forename: Keith
authors.initials: K
authors.lastname: Humphreys
authors.forename: Kamila
authors.initials: K
authors.lastname: Czene
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000071060:Breast Density; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology* / Q000628:therapy; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D042361:Mammary Glands, Human / Q000002:abnormalities*; D008327:Mammography; D008875:Middle Aged; D016017:Odds Ratio; D012042:Registries; D012306:Risk; D013548:Sweden / Q000453:epidemiology