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Test Code


Test Synonyms

PATHWAY (4B5), Immuno, Immunohistochemistry, Immunoperoxidase


Breast cancer; Herceptin


Technical component (TC) available

Turnaround Time

2 days

Specimen Requirements

Paraffin embedded tissue block
3 slides (3-5 uM) per marker on adhesion glass

Please note:
If submitting HER2 protein over-expression by immunohistochemistry,
HER2(ERBB2) gene amplification by in situ hybridization or estrogen /
progesterone receptor expression by immunohistochemistry, the specimen must
follow fixation guidelines listed below:
1. Specimens should be immersed in fixative within one hour of the biopsy or
2. If delivery of a resection specimen to the pathology department is delayed (eg,
specimens from remote sites), the tumor should be bisected prior to the
immersion in fixative. In such cases, it is important that the surgeon ensure
that the identity of the resection margins is retained in the bisected specimen;
alternatively, the margins may be separately submitted.
3. The time of removal of the tissue and the time of immersion of the tissue in
fixative should be recorded and submitted to the laboratory.

Specimen Stability
Indefinitely at room temperature
Storage & Handling

Ship ambient. Protect from extreme temperature with an ice pack. Separate ice pack from specimen.

Causes for Rejection

Improper specimen labeling; Insufficient sample; Inadequate fixation and/or processing

Reference Range

Normal breast tissues may produce positive reactivity scoring 1+ intensity, as will kidney, uterus and epithelium of the colon, stomach and small intestine. Normal tissues producing 2+ to 3+ staining intensity include esophageal epithelia, Langerhans cells, pituitary endocrine cells, prostate and squamous epithelia of tonsil.


In a fraction of patients with breast cancer, the HER2 protein is over expressed as part of the process of malignant transformation and tumor progression.  Over expression of the HER2 protein on the surface of breast cancer cells suggest that it could be a target for antibody therapy, Herceptin (Trastuzumab).

  1. Coussens L et al. (1985). Tyrosine kinase receptor with extensive homology to EGF receptor shares chromosomal location with neu oncogene. Science. 230:1132-9.
  2. King CR, Kraus MH, Aaronson SA. (1985). Amplification of a novel v-erbB-related gene in a human mammary carcinoma. Science. 229:974-6.



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