title: Quantitative comparison and reproducibility of pathologist scoring and digital image analysis of estrogen receptor β2 immunohistochemistry in prostate cancer.
abstract: BACKGROUND
  Digital image analysis offers advantages over traditional pathologist visual scoring of immunohistochemistry, although few studies examining the correlation and reproducibility of these methods have been performed in prostate cancer. We evaluated the correlation between digital image analysis (continuous variable data) and pathologist visual scoring (quasi-continuous variable data), reproducibility of each method, and association of digital image analysis methods with outcomes using prostate cancer tissue microarrays (TMAs) stained for estrogen receptor-β2 (ERβ2).
  
  
  METHODS
  Prostate cancer TMAs were digitized and evaluated by pathologist visual scoring versus digital image analysis for ERβ2 staining within tumor epithelium. Two independent analysis runs were performed to evaluate reproducibility. Image analysis data were evaluated for associations with recurrence-free survival and disease specific survival following radical prostatectomy.
  
  
  RESULTS
  We observed weak/moderate Spearman correlation between digital image analysis and pathologist visual scores of tumor nuclei (Analysis Run A: 0.42, Analysis Run B: 0.41), and moderate/strong correlation between digital image analysis and pathologist visual scores of tumor cytoplasm (Analysis Run A: 0.70, Analysis Run B: 0.69). For the reproducibility analysis, there was high Spearman correlation between pathologist visual scores generated for individual TMA spots across Analysis Runs A and B (Nuclei: 0.84, Cytoplasm: 0.83), and very high correlation between digital image analysis for individual TMA spots across Analysis Runs A and B (Nuclei: 0.99, Cytoplasm: 0.99). Further, ERβ2 staining was significantly associated with increased risk of prostate cancer-specific mortality (PCSM) when quantified by cytoplasmic digital image analysis (HR 2.16, 95 % CI 1.02-4.57, p = 0.045), nuclear image analysis (HR 2.67, 95 % CI 1.20-5.96, p = 0.016), and total malignant epithelial area analysis (HR 5.10, 95 % CI 1.70-15.34, p = 0.004). After adjusting for clinicopathologic factors, only total malignant epithelial area ERβ2 staining was significantly associated with PCSM (HR 4.08, 95 % CI 1.37-12.15, p = 0.012).
  
  
  CONCLUSIONS
  Digital methods of immunohistochemical quantification are more reproducible than pathologist visual scoring in prostate cancer, suggesting that digital methods are preferable and especially warranted for studies involving large sample sizes.
authors.affiliation: Department of Pathology, University of Washington, 908 Jefferson Street, Room 2NJB244, Seattle, WA, 98104, USA.|Department of Pathology, University of Washington, 300 Ninth Ave, Research & Training Building, Room 421, Seattle, WA, 98104, USA.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Rizzardi
authors.affiliation: Department of Urology, University of Washington, Seattle, WA, USA.
authors.forename: Xiaotun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Biostatistics and Bioinformatics Core, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Rachel Isaksson
authors.initials: RI
authors.lastname: Vogel
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Kolb
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
authors.forename: Milan S
authors.initials: MS
authors.lastname: Geybels
authors.affiliation: Divison of Environmental Genetics and Molecular Toxicology, University of Cincinnati, Cincinnati, OH, USA.|Center for Environmental Genetics, Cincinnati Cancer Institute, University of Cincinnati, Cincinnati, OH, USA.|Department of Environmental Health, Cincinnati Cancer Institute, University of Cincinnati, Cincinnati, OH, USA.
authors.forename: Yuet-Kin
authors.initials: YK
authors.lastname: Leung
authors.affiliation: Department of Pathology, University of Washington, 908 Jefferson Street, Room 2NJB244, Seattle, WA, 98104, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Henriksen
authors.affiliation: Divison of Environmental Genetics and Molecular Toxicology, University of Cincinnati, Cincinnati, OH, USA.|Center for Environmental Genetics, Cincinnati Cancer Institute, University of Cincinnati, Cincinnati, OH, USA.|Department of Environmental Health, Cincinnati Cancer Institute, University of Cincinnati, Cincinnati, OH, USA.
authors.forename: Shuk-Mei
authors.initials: SM
authors.lastname: Ho
authors.affiliation: Department of Pathology, University of Washington, 908 Jefferson Street, Room 2NJB244, Seattle, WA, 98104, USA.
authors.forename: Julianna
authors.initials: J
authors.lastname: Kwak
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.|Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Stanford
authors.affiliation: Department of Pathology, University of Washington, 908 Jefferson Street, Room 2NJB244, Seattle, WA, 98104, USA. sschmech@uw.edu.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Schmechel
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D013194:Staining and Labeling; D046888:Tissue Array Analysis
chemical_list: D014408:Biomarkers, Tumor; D047629:Estrogen Receptor beta
keywords: Biomarkers; Digital pathology; Estrogen receptor β2; Prostate cancer; Quantification