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

CPT: 88360
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  • 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

Specimen Requirements


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


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

Minimum Volume

Five unstained slides


Paraffin block transport pouch or slide mailer


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


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.


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


Immunohistochemistry (IHC)


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


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
484007 HER2 IHC RFX FISH, CRC 484328 HER-2/neu (C-erbB-2) Pending
484007 HER2 IHC RFX FISH, CRC 484330 Scoring Guide Pending
484007 HER2 IHC RFX FISH, CRC 484331 Comment Pending
484007 HER2 IHC RFX FISH, CRC 484332 Fixation Time Pending
484007 HER2 IHC RFX FISH, CRC 484333 Fixative Pending
484007 HER2 IHC RFX FISH, CRC 484325 Director Review Pending

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