Table 1.
Immunohistochemistry scoring for HER2 in gastric and gastrooesophageal junction cancer, by type of diagnostic specimen.
| IHC | Surgical specimen | Biopsy specimen | HER2 overexpression interpretation |
|---|---|---|---|
| 0 | No reactivity or membranous reactivity in <10% of tumour cells | No reactivity or no membranous reactivity in any tumour cell | Negative |
|
| |||
| + | Faint or barely perceptible membranous reactivity in ≥10% of tumour cells; cells are reactive only in part of their membrane | Tumour cell cluster with a faint or barely perceptible membranous reactivity irrespective of percentage of tumour cells stained | Negative |
|
| |||
| ++ | Weak to moderate complete, basolateral, or lateral membranous reactivity in ≥10% of tumour cells | Tumour cell cluster with a weak to moderate complete, basolateral, or lateral membranous reactivity irrespective of percentage of tumour cells stained | Equivocal |
|
| |||
| +++ | Strong complete, basolateral, or lateral membranous reactivity in ≥10% of tumour cells | Tumour cell cluster with a strong complete, basolateral, or lateral membranous reactivity irrespective of percentage of tumour cells stained | Positive |