HER2 by IHC, Colorectal, With Reflex to FISH if Equivocal

TEST: 484007
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CPT: 88360
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Synonyms

  • c-erb-2
  • Colorectal carcinoma
  • CRC
  • HER-2/neu
  • HER2
  • HER2 amplification
  • HER2 overexpression
  • Reflex HER2 FISH

Special Instructions

Testing will be delayed if the pathology report is not received. Fixation time and fixative used must be indicated on the test requisition form.

Expected Turnaround Time

5 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Specimen Requirements

Specimen

Formalin fixed paraffin-embedded (FFPE) tissue block or slides

Volume

One paraffin block or seven unstained, positively charged tissue slides cut at 4-5 microns

Minimum Volume

Five unstained slides

Container

Paraffin block transport pouch or slide mailer

Collection

Specimen should be fixed in a 10% neutral-buffered formalin. Cold ischemic time should be less than one hour and fixation time should be between six and 72 hours.

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Tumor type other than colorectal cancer (CRC); fixative other than neutral buffered formalin; insufficient tumor cellularity

Test Details

Use

HER2 is a known negative predictive biomarker in colorectal cancer (CRC). Recent trials have established HER2 as a therapeutic target in CRC. This assay assists in determining eligibility for HER2 therapy in patients with CRC.

Limitations

Use of fixatives other than 10% formalin may not yield reliable results.

Methodology

Immunohistochemistry (IHC)

References

Cercek A, Ng K, Strickler JH, et al. HER2 testing in colorectal cancer: concordance analysis between breast and gastric scoring algorithms from the MOUNTAINEER trial. J Clin Oncol. 2023 Feb 1;41:4_suppl, 198-198. doi: 10.1200/JCO.2023.41.4_suppl.198
Djaballah SA, Daniel F, Milani A, Ricagno G, Lonardi S. HER2 in colorectal cancer: the long and winding road From negative predictive factor to positive actionable target. Am Soc Clin Oncol Educ Book. 2022 Apr;42:1-14.35580290

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
484007 HER2 IHC RFX FISH, CRC 18474-7 484328 HER-2/neu (C-erbB-2) 18474-7
484007 HER2 IHC RFX FISH, CRC 18474-7 484330 Scoring Guide N/A
484007 HER2 IHC RFX FISH, CRC 18474-7 484331 Comment 77202-0
484007 HER2 IHC RFX FISH, CRC 18474-7 484332 Fixation Time N/A
484007 HER2 IHC RFX FISH, CRC 18474-7 484333 Fixative N/A
484007 HER2 IHC RFX FISH, CRC 18474-7 484325 Director Review 72486-4
484007 HER2 IHC RFX FISH, CRC 18474-7 484334 Bill Code Entry Hold N/A

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