Breast Biomarker Reporting

Independent ER, PgR, and HER2 modules (with ISH reflex) plus a combined final report.

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Educational and decision-support tool only. This application does not replace professional histopathological assessment, institutional protocols, or validated laboratory reporting.

Reference

ER / PgR — Allred proportion score

Intensity score: None = 0, Weak (1+) = 1, Moderate (2+) = 2, Strong (3+) = 3. Total Allred = Proportion + Intensity (0–8). A total of 0–2 is Negative; 3–8 is Positive.

Allred DC, et al. Prognostic and predictive factors in breast cancer by immunohistochemical analysis. Mod Pathol. 1998. ASCO/CAP Guideline Recommendations for Immunohistochemical Testing of Estrogen and Progesterone Receptors in Breast Cancer (updated 2020).

% positive cells	Proportion score
0%	0
<1%	1
1–10%	2
11–33%	3
34–66%	4
67–100%	5

HER2 IHC

IHC score	Interpretation
0	Negative
1+	Negative
2+	Equivocal — reflex to ISH
3+	Positive

HER2 ISH groups

Groups 2 and 4 require additional real-world workup (recounting, alternate tissue block, or repeat testing) that this calculator cannot perform — their final status is not automatically resolved here.

A valid ISH count needs at least 20 tumor cells (ASCO/CAP).

Wolff AC, et al. Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: ASCO/CAP Clinical Practice Guideline Focused Update. J Clin Oncol / Arch Pathol Lab Med. 2018.

ISH group	Ratio / avg HER2 copies	Result
Group 1	Ratio ≥2.0, HER2 ≥4.0	Positive
Group 2	Ratio ≥2.0, HER2 <4.0	Equivocal — additional workup required
Group 3	Ratio <2.0, HER2 ≥6.0	Positive
Group 4	Ratio <2.0, HER2 4.0–6.0	Equivocal — additional workup required
Group 5	Ratio <2.0, HER2 <4.0	Negative