ERBB2 (HER2/neu) (HercepTest) by Immunohistochemistry, Tissue with Reflex to FISH if 2+

Casandra

Casandra Test Code AR75293Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 0049178CPT Codes 88360, 88377

ERBB2 (HER2/neu) (HercepTest) by Immunohistochemistry, Tissue with Reflex to FISH if 2+

Also known as: HERCEP2IP

Clinical Use

Order Test

Use

The test aids in predicting the response to HER2-directed therapy in patients with breast carcinoma or gastroesophageal adenocarcinoma. It evaluates the expression level of HER2/neu proteins in the tumor tissue, helping to guide treatment decisions. The presence of HER2 overexpression detected by immunohistochemistry followed by reflex to FISH for equivocal results provides insight into the potential efficacy of targeted therapies such as trastuzumab.

Special Instructions

Refer to the ARUP Immunohistochemistry Stain Offerings brochure for more details. Submit tissue blocks or unstained slides along with a pathology report detailing the tissue source and tumor origin. Document the time from tissue acquisition to fixation and submit it with the order.

Limitations

Tissues fixed for outside the range of 6-72 hours in 10% neutral buffered formalin may produce unreliable results. Decalcified specimens should be interpreted with caution due to the potential for false-negative results. The interpretation is limited to breast and gastric cancers per FDA approval. The presence of tumor heterogeneity may affect test accuracy.

Test Details

FDA Approved

New York Approved

Methodology

Immunoassay (IHC)

Biomarkers

ERBB2

Protein

IHC • Expression • Ordinal Score (e.g., TPS, CPS, H-score)

LOINC Codes

Result Codes

18474-7
94736-6
31208-2

Result Turnaround Time

1-5 days

Specimen

Tissue (FFPE)

Volume

Not provided

Minimum Volume

6 slides

Collection Instructions

Formalin fix (10 percent neutral buffered formalin) and paraffin embed tissue within 30 minutes of removal from patient. Use ARUP supply #47808 for transport.

Storage Instructions

Transport at room temperature or refrigerated; ship in a cooled container during summer months.

Causes for Rejection

Paraffin block with no tumor tissue remaining. Delay in fixation for more than one hour. Usage of other fixatives besides 10% neutral buffered formalin. Tissue under-fixed or over-fixed outside the specified 6-72 hours range.