YEAR | LESION/MATERIAL EXAMINED | HER2 IHC | HER2 FISH | Respective ASCO/CAP GUIDELINE definition for HER2 positive IHC result | Respective ASCO/CAP GUIDELINE definition for HER2 positive ISH result |
---|---|---|---|---|---|
2010 | Primary tumor surgical resection specimen | 20% of tumor cells showed complete, intense circumferential membrane reaction: 2+ (SP3 antibody) | Polysomy of Chr17 suggested: many tumor cells showed 3–6 HER2 copies/cell Interpreted as HER2 negative (single probe ISH assay) | 2007 ASCO/CAP guideline > 30% of tumor cells show complete, intense circumferential reaction | 2007 ASCO/CAP guideline > 6 HER2copy/cell (single probe ISH) > 2.2 HER2/CEN17 ratio/cell (dual probe ISH) |
2017 | Metastasis (sternum region) | 20% of tumor cells showed complete, weak or moderate, circumferential membrane reaction: 2+ (4B5 antibody) | 30% of tumor cells showed polysomy-co-amplification (3–6 CEP17 signals and 6–10 HER2 signals/cells; dual probe ISH assay) Interpreted as HER2 positive | 2013 ASCO/CAP guideline > 10% of tumor cells show complete, in tense circumferential reaction | 2013 ASCO/CAP guideline See: Wolff AC et al. Arch Pathol Lab Med. 2014 Feb; 138 (2): 241–256. |
2017 | Metastasis (brain – analysis following second opinion request) | 15–20% of the tumor cells showed complete, weak or moderate, circumferential membrane reaction: 2+ (4B5 antibody) | 80 tumor cells were counted: mean HER2 copy number/cell was 4.0, mean HER2/CEP17 ratio was 1.62. However, scattered, heterogeneous amplification was present: In 43% of the tumor cells 4.6 HER2/cell was found and the HER2/CEP17 ratio was 2.4. (dual probe ISH assay) Interpreted as heterogeneous amplification, HER2 negative | 2013 ASCO/CAP guideline > 10% of tumor cells show complete, intense circumferential reaction | 2013 ASCO/CAP guideline and 2009 CAP guidelines for genetic heterogeneity in HER2 testing: „HER2 genetic heterogeneity (GH) exists if there are more than 5% but less than 50% of infiltrating tumor cells with a ratio higher than 2.2 …. If more than 50% of the infiltrating tumor cells have a ratio higher than 2.2, then the tumor is considered HER2 amplified.” |