Breast biomarkers testing click to access further explanations in the original CAP template

- Clustered Heterogeneity :
HER2 DISH calculator
- Number of tumor cells counted :
- Average HER2 signals (black) per cell :
- Average CEP17 signals (red) per cell :
- HER2/CEP17 ratio :
- Cells with Amplified Signals (%):
- Other ISH abnormalities:

min
hours

- Per review after 2024 CAP site inspection
- Please fill in/estimate the cold ischemic time (in minutes) and formalin-fixation time (in hours).
- Optimal cold ishemic time less than or equal to 60 min
- Optimal formalin-fixation time 6-72 hours.


HER2 DISH calculator
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PD-L1 calculator
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- Group 1 = Ratio greater than or equal to 2.0 and greater than or equal to 4.0 HER2 signals / cell
- Group 2 = Ratio greater than or equal to 2.0 and less than 4.0 HER2 signals / cell =
- Group 3 = Ratio less than 2.0 and greater than or equal to 6.0 HER2 signals / cell
- Group 4 = Ratio less than 2.0 and greater than or equal to 4.0 and less than 6.0 HER2 signals / cell
- Group 5 = Ratio less than 2.0 and less than 4.0 HER2 signals / cell

Negative : - Group 5;
- Group 4 and concurrent IHC 0-1+ or 2+;
- Group 3 and concurrent IHC 0-1+; and
- Group 2 and concurrent IHC 0-1+ or 2+;

Positive : - Group 1;
- Group 2 and concurrent IHC 3+;
- Group 3 and concurrent IHC 2+ or 3+; and
- Group 4 and concurrent IHC 3+


HER2 IHC
From Venetis et al Front. Mol. Biosci. 2022.

In the DESTINY-Breast 04 and 06 trials, “HER2 low” was considered IHC Score 1+ or 2+ / ISH negative, and “HER2 ultralow” was HER2 IHC Score of 0 (pattern 0+) with membrane staining that is incomplete and faint / barely perceptible in less than or equal to 10% of tumor cells. Breast cancers with these staining patterns may be eligible for treatment with trastuzumab-deruxtecan in the metastatic setting (but those with no staining, IHC 0, are currently excluded)

HER2-low
HER2 IHC 2+ AND HER2 DISH negative OR HER2 IHC 1+
Tarantino P et al. 2020

HER2 Ultra-low
It is immunohistochemically characterized by faint/barely perceptible and incomplete staining in =<10% of tumor cells without amplification on FISH.