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Human Epidermal Growth Factor Receptor 2 (HER2) Test via Tissue Sample—Quantitative Analysis

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of HER2 protein in a sample of your tumor tissue to help determine if targeted cancer treatments may be effective.

Quick summary

["Assists doctors in deciding if targeted therapy could be a good option for your cancer treatment plan."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
18474-7
Short code
Her2 Ag Tiss Ql ImStn
Synonyms
Her2 Ag Tiss Ql ImStn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immune-stain
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have breast, stomach, or another type of cancer that is known to respond to HER2-targeted therapies. It helps identify whether your tumor has an abnormal amount of HER2 protein, which can influence treatment choices.

How the Test Works

A small sample of your tumor tissue is taken during surgery or a biopsy. The lab analyzes the sample using advanced techniques to measure HER2 levels, often through techniques like immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH).

What to Expect Before the Test

You may need to prepare by avoiding certain medications or fasting, depending on the procedure. Your doctor will guide you on any specific instructions for your biopsy or tissue collection.

What the Results Mean

Results are typically reported as a score (e.g., 0, 1+, 2+, 3+) or a positive/negative determination. A score of 3+ or positive indicates high HER2 levels, which may mean targeted therapies could be beneficial. A score of 0, 1+, or negative suggests lower HER2 levels, which may influence other treatment options.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HER2 Status by Tissue

Frequently asked questions

How does this test affect my cancer treatment options?
If your HER2 test is positive, your doctor may recommend targeted therapies like trastuzumab (Herceptin) or other HER2-directed drugs. If negative, other treatments may be suggested based on your cancer type and stage.
Can false results happen, and how can I ensure accuracy?
Testing accuracy depends on the lab’s quality and the sample’s quality. Follow your doctor’s instructions for biopsy or tissue handling to reduce errors. Confirm results with your healthcare team if you have concerns.
What if my test results are unclear or conflicting?
If results are ambiguous, your doctor may order additional tests or repeat the analysis. This helps ensure the most accurate understanding of your tumor’s HER2 status for treatment planning.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy