HercepTest Staining

Interpretation of HER2 Overexpression

To determine the score for HER2 overexpression, the staining patterns are characterized below.  Slide evaluation is performed by a pathologist using a light microscope.

  

Staining Pattern Score HER2 Overexpression Assessment Example Stain

No staining is observed or membrane staining is observed in less than 10% of the tumor cells

0

Negative

A faint/barely perceptible membrane staining is detected in more than 10% of the tumor cells.  The cells are only stained in part of their membrane.

1+

Negative
A weak to moderate complete membrane staining is observed in more than 10% of the tumor cells

2+

Weak Positive
a moderate to strong complete membrane staining is observed in more than 10% of the tumor cells

3+

Strong Positive