title: Flat epithelial atypia and risk of breast cancer: A Mayo cohort study.
abstract: BACKGROUND
  Based on its cytologic features, and its co-occurrence with atypical hyperplasia and breast cancer, flat epithelial atypia (FEA) has been proposed as a precursor lesion on the pathway to the development of breast cancer. It is often referred to as an "atypical" or high-risk lesion. However, to the authors' knowledge, the long-term risk of breast cancer in women with FEA is undefined.
  
  
  METHODS
  Specimens with FEA were identified among excisional breast biopsies in the Mayo Clinic Benign Breast Disease Cohort, which includes 11,591 women who had benign biopsy findings at the Mayo Clinic in Rochester, Minnesota between 1967 and 2001. Breast cancer risk among subsets of patients with FEA and nonproliferative, proliferative, and atypical hyperplasia (AH) was assessed using standardized incidence ratios (SIRs) compared with the Iowa Surveillance, Epidemiology, and End Results registry.
  
  
  RESULTS
  FEA was identified in 282 women (2.4%); 130 had associated AH (46%) and 152 (54%) were classified as having proliferative disease without atypia (PDWA). With median follow-up of 16.8 years, the SIR for breast cancer in patients with AH plus FEA was 4.74 (95% confidence interval [95% CI], 3.17-6.81) versus 4.23 (95% CI, 3.44-5.13) for those with AH without FEA (P = .59). The SIR for patients with PDWA plus FEA was 2.04 (95% CI, 1.23-3.19) versus 1.90 (95% CI, 1.72-2.09) for patients with PDWA without FEA (P = .76).
  
  
  CONCLUSIONS
  FEA is an uncommon finding in women with benign breast disease. FEA does not appear to convey an independent risk of breast cancer beyond that of the associated PDWA or AH.
authors: Division of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota.
authors: Samar M
authors: SM
authors: Said
authors: Daniel W
authors: DW
authors: Visscher
authors: Aziza
authors: A
authors: Nassar
authors: Ryan D
authors: RD
authors: Frank
authors: Robert A
authors: RA
authors: Vierkant
authors: Marlene H
authors: MH
authors: Frost
authors: Karthik
authors: K
authors: Ghosh
authors: Derek C
authors: DC
authors: Radisky
authors: Lynn C
authors: LC
authors: Hartmann
authors: Amy C
authors: AC
authors: Degnim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000379:methods; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000473:pathology / Q000601:surgery; D015331:Cohort Studies; D004847:Epithelial Cells / Q000473:pathology*; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000175:diagnosis / Q000453:epidemiology; D015994:Incidence; D007484:Iowa / Q000453:epidemiology; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D016017:Odds Ratio; D011230:Precancerous Conditions / Q000175:diagnosis* / Q000453:epidemiology* / Q000473:pathology / Q000601:surgery; D018570:Risk Assessment; D012307:Risk Factors; D018426:SEER Program
keywords: atypia; breast cancer; columnar cell lesion of breast; flat epithelial atypia; proliferative disease without atypia
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