title: Possible influence of mammographic density on local and locoregional recurrence of breast cancer.
abstract: BACKGROUND
  It is debated whether mammographic density gives rise to more aggressive cancers. We therefore aimed to study the influence of mammographic density on prognosis.
  
  
  METHODS
  This is a case-only study within a population-based case-control study. Cases were all postmenopausal women in Sweden with incident breast cancer, diagnosed 1993-1995, and aged 50-74 years. Women with pre-diagnostic/diagnostic mammograms were included (n = 1774). Mammographic density of the unaffected breast was assessed using a computer-assisted thresholding technique. The Cox proportional hazards model was used to study recurrence and survival with and without stratification on surgical procedure (breast-conserving surgery vs. mastectomy).
  
  
  RESULTS
  Percentage density (PD) was associated with both local and locoregional recurrence even after adjustment for established prognosticators; hazards ratio (HR) 1.92, p = 0.039, for local recurrence and HR 1.67, p = 0.033, for locoregional recurrence for women with PD≥25% compared to PD<25%. Stratification on surgical procedure showed that the associations were also present in mastectomized women. PD was neither associated with distant recurrence nor survival.
  
  
  CONCLUSIONS
  High mammographic density is an independent risk factor of local and locoregional recurrence but is neither associated with distant metastasis nor survival. The relationships with local and locoregional recurrences were also present in women treated with mastectomy, indicating that they are not merely explained by density masking residual disease in women treated with breast-conserving surgery. Rather there appears to be a true association. Thus, mammographic density should possibly influence adjuvant therapy decisions in the future.
authors.forename: Louise
authors.initials: L
authors.lastname: Eriksson
authors.forename: Kamila
authors.initials: K
authors.lastname: Czene
authors.forename: Lena
authors.initials: L
authors.lastname: Rosenberg
authors.forename: Keith
authors.initials: K
authors.lastname: Humphreys
authors.forename: Per
authors.initials: P
authors.lastname: Hall
mesh_terms: D000368:Aged; D000071060:Breast Density; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology* / Q000628:therapy; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D042361:Mammary Glands, Human / Q000002:abnormalities*; D008327:Mammography; D008875:Middle Aged; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011379:Prognosis; D012042:Registries; D013548:Sweden