HER2 immunohistochemistry (IHC) is a technique used to assess the expression of the HER2 receptor in breast cancer tissues.

The HER2 protein is a growth factor receptor that, when overexpressed, is associated with more aggressive forms of breast cancer. IHC staining for HER2 involves applying an antibody that binds to the HER2 protein on the cell surface, which is then visualized using a chromogen.

The staining is scored on a scale from 0 to 3+, with 3+ indicating strong, uniform membrane staining in more than 10% of tumor cells, suggesting HER2 positivity. This scoring is critical for determining eligibility for HER2-targeted therapies like trastuzumab.

PAIKON for IHC HER2 testing is currently availible as RUO product for microscopic and whole slide images.