Her-2/neu

Also known as: HER-2/neu; c-erbB-2; HER2

Formal name: Human epidermal growth factor receptor

Related tests: Hormone Receptor Status; Tumor markers

The Test Sample

What is being tested?

Her-2/neu is an oncogene. It is a gene that codes for a protein that is a receptor for a particular growth factor that promotes cell growth. Normal epithelial cells found throughout the body contain two copies of the Her-2/neu gene and produce low levels of the Her-2/neu protein on the surface of their cells. In about 20-30% of invasive breast cancers (and some other cancers, such as ovarian and bladder cancer), the Her-2/neu gene is amplified and its protein is over-expressed. that have this over-expression tend to grow more aggressively and resist endocrine (anti-hormone) therapy and some chemotherapies. People with Her-2/neu positive breast cancers tend to have a poorer prognosis, but this tumor characteristic also makes them candidates to receive treatment specific for Her-2/neu-positive cancers.

To determine if a tumor is positive for Her-2/neu, a biopsy is taken and the sample of tumor is tested. There are two main ways to test Her-2/neu status: immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH). IHC measures the amount of Her-2/neu protein present. FISH looks at the genetic level for actual gene amplification – the number of copies of the gene present. IHC is currently the most widely used initial testing method; however, if it is indeterminate or negative, then the FISH method is often done as a follow-up test.

A Her2/neu test blood test is also available. The amount of Her-2/neu protein present in the serum is loosely associated with the amount of Her-2/neu -positive cancer present. This test is not used for screening purposes and is not a substitute for tissue testing but may be ordered to help assess a person's prognosis and to monitor the effectiveness of treatment. After an initial diagnosis of metastatic breast cancer is made, this blood test may be performed and, if the initial level is greater than 15 ng/mL, then the test may be used to monitor treatment.

How is the sample collected for testing?

A sample of breast cancer tissue is obtained by doing a fine needle aspiration, needle biopsy, or surgical biopsy. For the Her-2/neu blood test, a blood sample is drawn from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.