Interobserver concordance in implementing the 2010 ASCO/CAP recommendations for reporting er in breast carcinomas: A demonstration of the difficulties of consistently reporting low levels of er expression by manual quantification

Emily S. Reisenbichler, Susan C. Lester, Andrea L. Richardson, Deborah A. Dillon, Amy Ly, Jane E. Brock

Research output: Contribution to journalArticlepeer-review

Abstract

Objectives: Endocrine therapy reduces recurrence risk by 30% to 50% in estrogen receptor (ER)-positive breast cancer. The ER-positive threshold recommended by the American Society of Clinical Oncology/College of American Pathologists is 1% based on studies using the ER-6F11 antibody. ER-SP1 antibody has a higher sensitivity and is more widely used. Methods: We report interobserver concordance manually measuring ER in 264 breast cancers using ER-SP1 and 1D5 and 2 scoring methods (H-score and Allred score). Results: With both antibodies, 3% to 4% of cases have a low level of ER expression (1%-10%), more than previously reported (<1%). We find a high level of paired observer concordance with both antibodies and scoring methods (k = 0.892-0.943) with no significant difference with method of scoring. Despite excellent concordance, positive/negative discordance was almost 5% among 3 observers using either antibody, an underappreciated clinically significant rate. Conclusions: Discordance overwhelmingly reflected differing opinions recording the proportion of tumor cells positive with low levels of expression (<10% staining; 12/13 cases).

Original languageEnglish (US)
Pages (from-to)487-494
Number of pages8
JournalAmerican journal of clinical pathology
Volume140
Issue number4
DOIs
StatePublished - Oct 1 2013
Externally publishedYes

Keywords

  • Breast carcinoma
  • Concordance
  • Estrogen receptor
  • Immunohistochemistry

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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