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HER-2/neu IHC, Breast Paraffin

CPT 88360
Synonyms
  • c-erb-2

Test Details

Turnaround Time

2 - 4 days

View Requisition Forms

Use

Equivocal results by IHC should be reflexed to HER2 FISH to determine overall status. HER-2/neu overexpression is a predictor of response to certain breast cancer therapies, including targeted immunotherapies.1-3 A positive IHC result (3+) or an equivocal result with ISH amplification provides eligibility for trastuzumab (HERCEPTIN®) and trastuzumab emtansine (KADCYLA®) therapies. This test can also be used to qualify patients as HER2-low (1+ IHC or 2+/ISH-) or HER2-ultralow (any staining of the membrane in greater than 0 and less than or equal to 10% of invasive tumor cells) for fam-trastuzumab-deruxtecan-nxki (ENHERTU®) eligibility determination.

Special Instructions

Fixation time and fixative used must be indicated on the test request form. Please direct any questions regarding this test to oncology customer service at 800-345-4363.

Limitations

Use of fixatives other than 10% neutral-buffered formalin or fixation times less than six hours or more than 72 hours may not yield reliable results. Decalcification procedures may negatively affect antigenicity and DNA quality.

Methodology

Immunohistochemistry (IHC)

References

Modi S, Jacot W, Yamashita T, Petukhova MN, Agafonov SV, Itkin GP. Trastuzumab Deruxtecan in Previously Treated HER2-Low Advanced Breast Cancer. N Engl J Med. 2022 Jul 7;387(1):9-20. PubMed 35665782

PATHWAY anti-HER-2/neu (4B5) Rabbit Monoclonal Primary Antibody [package insert]. Roche Diagnostics; Jan 29, 2025.

Wolff AC, Hammond MEH, Allison KH, et al. Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update. J Clin Oncol. 2018 Jul 10;36(20):2105-2122. PubMed 29846122

Specimen Requirements

Information on collection, storage, and volume

Specimen

Formalin-fixed, paraffin-embedded (FFPE) tumor

Volume

One paraffin block or five unstained, positively-charged tissue slides cut at 4 to 5 microns and dried for one hour at 60°C

Container

Paraffin block transport pouch or slide mailer

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Tumor other than breast tumor

Collection

Specimen should be fixed in 10% neutral-buffered formalin. Time from tissue acquisition to fixation should be as short as possible. Fixation time should be between six and 72 hours according to ASCO/CAP guidelines.

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