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What Is HER2-Positive Breast Cancer?

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What Is HER2-Positive Breast Cancer?

About 20% to 25% of breast cancers are HER2-positive. That means they have a certain protein (HER2/neu) that makes cancer cells grow. This kind of cancer tends to be much more aggressive and fast-growing than other kinds of breast cancer, but there are effective treatments that target HER2.

Your doctor will test your cancer to find out if yours is HER2-positive and also check on whether it has spread and if it's sensitive to hormones.

 

Causes

Researchers aren't sure what causes breast cancer. They think it may be a combination of things, including your genes, your environment, and your lifestyle. Every case is different.

In HER2-positive breast cancer, a gene causes cancer cells to make too much HER2/neu protein. When that happens, cancer cells grow in an out-of-control way.

This only happens in cancer cells. It can happen in other cancers, too -- not just breast cancer.

You can't inherit a bad copy of this gene from a parent or pass it on to your children.

Symptoms

The most common symptom of any type of breast cancer is a lump in your breast that feels different from the area around it.

Other symptoms include:

  • Breast swelling or a change in the shape of the breast
  • Skin irritation or dimpling
  • Pain in the breast or nipple
  • Redness or thickness of the nipple or breast skin
  • Discharge from the nipple (not breast milk)

You may have noticed a difference in your breasts during a self-exam, or you may have had a mammogram that showed the cancer. 

Getting a Diagnosis

When you're diagnosed with breast cancer, your doctor will test for HER2. There are four types of tests for HER2-positive breast cancer.

The IHC test (immunohistochemistry) checks for how much HER2 protein is in a sample of breast cancer tissue.

Three other tests check to see if there are too many HER2 genes in the cancer cells:

  1. FISH test (fluorescence in-situ hybridization)
  2. SPOT-Light HER2 CISH test (subtraction probe technology chromogenic in-situ hybridization)
  3. Inform HER2 Dual ISH test (inform dual in-situ hybridization)

Sometimes the results of one test aren't clear, and your doctor may order another type of test.

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