Interpretation Guidelines

HercepTest™ Staining: Interpretation of HER2 Overexpression

Staining Pattern Score Assessment Example Stain
No staining is observed or a 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 + Weakly positive (Equivocal)
A strong complete membrane staining is observed in more than 10% of the tumor cells. 3 + Strongly positive

HercepTest™ Scoring Guidelines

  • Validation of the assay
  • Evaluate control cell lines
  • Verify negative control is negative
  • Invalidate the assay, if cell lines fail to stain properly or, if negative control stains positive

CLICK HERE TO SEE THE TABLE OF SLIDE READING ORDER AND RATIONALE

Recommendations for Interpretation

  • Use of an H&E stainer is recommended for initial evaluation.
  • Only evaluate the membrane staining.
  • Evaluate HER2 sections at low power first.
  • If a majority of the cells are obviously stained, the staining is either 2+ or 3+.
  • In 3+ cases, at least 80% of the tumor cells will usually be stained and the staining intensity will be strong.
  • If a moderate staining is observed in >10% of the cells and they are not cytoplasmic, the staining is 2+.
  • If a complete circumferential membranous staining is observed in less >10% of the tumor cells, the staining is 1+ or 0.