HER2 Tumor Marker Test

The HER2 tumor marker test is a diagnostic tool used to determine if a person's cancer cells have an overexpression or amplification of the human epidermal growth factor receptor 2 (HER2) protein.

What is HER2?

HER2 is a gene that helps control cell growth, division, and repair. In some cases of cancer, particularly breast and ovarian cancer, the HER2 gene can become altered, leading to an overproduction of the HER2 protein on the surface of cancer cells.

Purpose of the Test

The primary purpose of the HER2 tumor marker test is to identify patients with cancers that may benefit from targeted therapies, such as trastuzumab (Herceptin), which specifically target the HER2 protein.

Types of HER2 Tests

There are two main types of HER2 tests:

• Immunohistochemistry (IHC) test: This test measures the level of HER2 protein on the surface of cancer cells.
• Fluorescence in situ hybridization (FISH) test: This test measures the number of copies of the HER2 gene in cancer cells.

How the Test is Performed

A sample of tissue from the tumor is removed during a biopsy or surgery and sent to a laboratory for analysis. The tissue sample is then examined using either IHC or FISH techniques to determine the level of HER2 protein or gene amplification.

Interpretation of Results

The results of the HER2 test are typically reported as:

• HER2-positive: The cancer cells have an overexpression or amplification of the HER2 protein, and targeted therapies may be effective.
• HER2-negative: The cancer cells do not have an overexpression or amplification of the HER2 protein, and targeted therapies may not be effective.
• Borderline or equivocal results: The results are unclear, and additional testing may be necessary to determine the HER2 status.

Clinical Significance

The HER2 tumor marker test has significant implications for the diagnosis, treatment, and prognosis of certain types of cancer. Patients with HER2-positive cancers may benefit from targeted therapies, which can improve treatment outcomes and survival rates.

Frequently Asked Questions (FAQs)

What is the HER2 tumor marker test?
A laboratory test used to detect the presence of the HER2 protein on cancer cells.

Why is the HER2 tumor marker test performed?
To help diagnose and guide treatment for certain types of cancer, particularly breast cancer.

How is the HER2 tumor marker test typically conducted?
Through a biopsy or surgical sample of tissue from the tumor.

What are the possible results of the HER2 tumor marker test?
The results can be positive (HER2-positive) or negative (HER2-negative), indicating the presence or absence of the HER2 protein.

What does a positive HER2 result indicate?
A higher likelihood of aggressive cancer growth, but also potential responsiveness to targeted therapies.

What is the significance of a negative HER2 result?
The cancer may be less likely to respond to certain targeted therapies, and other treatment options may be considered.

Is the HER2 tumor marker test used for all types of cancer?
No, it is primarily used for breast cancer, but can also be used for other cancers such as stomach or esophageal cancer.

Are there different methods for conducting the HER2 tumor marker test?
Yes, including immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH).

How accurate is the HER2 tumor marker test?
The accuracy can vary depending on the testing method and laboratory, but it is generally considered to be a reliable diagnostic tool.

Can the HER2 tumor marker test results change over time?
Yes, the HER2 status of a tumor can potentially change during the course of treatment or disease progression.