title: Variability in Pathologists' Interpretations of Individual Breast Biopsy Slides: A Population Perspective.
abstract: The effect of physician diagnostic variability on accuracy at a population level depends on the prevalence of diagnoses.
  
  
  
  To estimate how diagnostic variability affects accuracy from the perspective of a U.S. woman aged 50 to 59 years having a breast biopsy.
  
  
  
  Applied probability using Bayes' theorem.
  
  
  
  B-Path (Breast Pathology) Study comparing pathologists' interpretations of a single biopsy slide versus a reference consensus interpretation from 3 experts.
  
  
  
  115 practicing pathologists (6900 total interpretations from 240 distinct cases).
  
  
  
  A single representative slide from each of the 240 cases was used to estimate the proportion of biopsies with a diagnosis that would be verified if the same slide were interpreted by a reference group of 3 expert pathologists. Probabilities of confirmation (predictive values) were estimated using B-Path Study results and prevalence of biopsy diagnoses for women aged 50 to 59 years in the Breast Cancer Surveillance Consortium.
  
  
  
  Overall, if 1 representative slide were used per case, 92.3% (95% CI, 91.4% to 93.1%) of breast biopsy diagnoses would be verified by reference consensus diagnoses, with 4.6% (CI, 3.9% to 5.3%) overinterpreted and 3.2% (CI, 2.7% to 3.6%) underinterpreted. Verification of invasive breast cancer and benign without atypia diagnoses is highly probable; estimated predictive values were 97.7% (CI, 96.5% to 98.7%) and 97.1% (CI, 96.7% to 97.4%), respectively. Verification is less probable for atypia (53.6% overinterpreted and 8.6% underinterpreted) and ductal carcinoma in situ (DCIS) (18.5% overinterpreted and 11.8% underinterpreted).
  
  
  
  Estimates are based on a testing situation with 1 slide used per case and without access to second opinions. Population-adjusted estimates may differ for women from other age groups, unscreened women, or women in different practice settings.
  
  
  
  This analysis, based on interpretation of a single breast biopsy slide per case, predicts a low likelihood that a diagnosis of atypia or DCIS would be verified by a reference consensus diagnosis. This diagnostic grey zone should be considered in clinical management decisions in patients with these diagnoses.
  
  
  
  National Cancer Institute.
authors.forename: Joann G
authors.initials: JG
authors.lastname: Elmore
authors.forename: Heidi D
authors.initials: HD
authors.lastname: Nelson
authors.forename: Margaret S
authors.initials: MS
authors.lastname: Pepe
authors.forename: Gary M
authors.initials: GM
authors.lastname: Longton
authors.forename: Anna N A
authors.initials: AN
authors.lastname: Tosteson
authors.forename: Berta
authors.initials: B
authors.lastname: Geller
authors.forename: Tracy
authors.initials: T
authors.lastname: Onega
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Carney
authors.forename: Sara L
authors.initials: SL
authors.lastname: Jackson
authors.forename: Kimberly H
authors.initials: KH
authors.lastname: Allison
authors.forename: Donald L
authors.initials: DL
authors.lastname: Weaver
mesh_terms: D001499:Bayes Theorem; D001706:Biopsy; D000071960:Breast Carcinoma In Situ / Q000175:diagnosis; D001943:Breast Neoplasms / Q000175:diagnosis*; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis; D002983:Clinical Competence; D005260:Female; D006801:Humans; D008875:Middle Aged; D000072142:Pathologists / Q000592:standards*; D012015:Reference Standards