Human epidermal growth factor receptor 2

Keywords: HER-2, c-erb B-2

Description:

See Breast biopsy.

Specimen:

Formalin-fixed paraffin embedded breast tissue.

Method:

Standard immunohistochemical staining with graded positive and negative on-slide control tissue.

Application:

Overexpression of HER-2 protein occurs in 10 to 40% of primary breast carcinoma. Immunostaining is undertaken for identification of HER-2 positive tumours and assessment of response to recombinant humanised anti-HER-2 antibody (HerceptinTM) therapy.

Interpretation:
  • Absence of staining or <10% tumour cells stained - score as 0, interpret as negative.
  • Faint, cytoplasmic membrane stain involving only part of the membrane in 10% of tumour cells - score as 1+, interpret as negative.
  • Weak to moderate membranous staining in 10% tumour cells - score as 2+, interpret as weak positive.
  • Strong and complete membrane staining in >10% tumour cells - score as 3+, interpret as strong positive.
  • Weak positive results are usually confirmed by FISH or CISH testing for HER-2 amplification.
Reference:

Demonty G, Bernard-Marty C et al. Progress and new standards of care in management of HER-2 positive breast cancer. Eur J Cancer. 2007; 43: 497-509.