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

CPT 88360
  • c-erb-2
  • Colorectal carcinoma
  • CRC
  • HER-2/neu
  • HER2
  • HER2 amplification
  • HER2 overexpression
  • Reflex HER2 FISH

Test Details

Cancer Type

Colorectal cancer (CRC)

Technology Used


Turnaround Time

5 days


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.

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.


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

Specimen Requirements

Information on collection, storage, and volume


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

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


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.