Clinical Significance: 
The American Society of Clinical Oncologists (ASCO), ASCP, CAP, AMP, and National Comprehensive Cancer Network (NCCN) recommend HER2 gene amplification status determination on colorectal cancer patients inappropriate for intensive systemic therapy in a setting of advanced or metastatic disease. Anti-HER2 therapy is only indicated for HER2-amplified tumors that are also RAS and BRAF wild-type.

https://www.nccn.org/professionals/physician_gls/pdf/colon.pdf

Specimen Requirements and Collection:
This FISH assay is performed using formalin-fixed paraffin-embedded tissue sections. 

Methodology:
Fluorescent in-situ hybridization (FISH)

Forms:
Molecular Pathology requisition form

Transport:
Send formalin-fixed, paraffin-embedded (FFPE) tissue and cell block containing tumor at room temperature.  Also acceptable 2-unstained, 4-5 micron slides with 1 post H&E.  Please include a surgical pathology report.

Unacceptable specimen:
Specimens fixed in alternative fixatives or metal fixatives (ex. B-plus).  Decalcified specimens.

Reference Range:
HER2/CEP17 ratio < 2.0 = HER2 gene amplification ABSENT
Ratio >= 2.0 in more than 50% of cells analyzed = HER2 gene amplification PRESENT

CPT codes:
88377

Test reported:
Results are reported within 4-7 days