# American Society of Clinical Oncology/College Of American Pathologists guideline recommendations for immunohistochemical testing of estrogen and progesterone receptors in breast cancer

Source: https://onco.cc/key-papers/paper-asco-cap-er-pr-testing-guideline-jco-2010/  
OnCo record `paper-asco-cap-er-pr-testing-guideline-jco-2010` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The 2010 rule that fixed the line between hormone receptor-positive and negative breast cancer at 1 percent of stained tumour nuclei, after finding that up to a fifth of receptor tests worldwide might be wrong; it is the threshold that defines triple-negative disease.

## Summary

ASCO and College of American Pathologists guideline by Hammond, Hayes, Dowsett, Allred and colleagues, developed with Cancer Care Ontario from a systematic review. Up to 20 percent of immunohistochemical oestrogen and progesterone receptor determinations worldwide may be inaccurate, mostly through variation in pre-analytic handling, positivity thresholds and interpretation. The panel recommends that receptor status be determined on all invasive breast cancers and recurrences, proposes a testing algorithm with specified elements to reduce assay variation, and recommends that assays be considered positive if at least 1 percent of tumour nuclei stain in the presence of expected internal and external control reactivity. The absence of endocrine therapy benefit in receptor-negative disease has been confirmed in large overviews of randomised trials.

## Fields

- Kind: Key paper
- Last checked: 2026-09-24
- Tags: tnbc-evidence
- Journal: Journal of Clinical Oncology
- Year: 2010
- DOI: 10.1200/JCO.2009.25.6529
- Authors: Hammond ME, Hayes DF, Dowsett M, et al.
- Findings: Up to 20 percent of immunohistochemical oestrogen and progesterone receptor determinations worldwide may be inaccurate.; Positive defined as at least 1 percent of tumour nuclei staining with expected control reactivity.
- What it means: Triple-negative is a laboratory definition; this guideline wrote the oestrogen and progesterone half of it, and the 1 to 10 percent low-positive band it created is still argued over.
- Caveats: Immunohistochemistry thresholds are conventions; tumours with 1 to 10 percent staining behave more like receptor-negative disease in several series.; Predates the HER2-low and HER2-ultralow categories.

## Sources

- J Clin Oncol 2010: https://doi.org/10.1200/JCO.2009.25.6529
- PubMed: https://pubmed.ncbi.nlm.nih.gov/20404251/

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [Digital pathology & AI](https://onco.cc/technologies/digital-pathology-ai/)
- institutions: [American Society of Clinical Oncology (ASCO)](https://onco.cc/institutions/asco/)
- terms: [Immunohistochemistry (IHC)](https://onco.cc/terms/ihc/)
- bottlenecks: [Biomarkers are not validated or standardised](https://onco.cc/bottlenecks/b-biomarker-validation/)
- journals: [Journal of Clinical Oncology](https://onco.cc/journals/jco/)
- roadmaps: [Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem](https://onco.cc/roadmaps/tnbc-roadmap/)
- key papers: [Slamon 1987: HER2 gene amplification marks an aggressive form of breast cancer](https://onco.cc/key-papers/paper-slamon-her2-amplification-science-1987/)

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