What Is HER2-Positive Breast Cancer?

If your breast cancer is “HER2-positive,” it’s more aggressive than other types of breast tumors, but treatments can help.

About 1 of 5 of breast cancers are HER2-positive. That means the cancer cells have more of a protein called HER2. It causes these cells to grow and spread faster than the ones with normal levels of the protein.

You’ll work with your doctor to review the treatment options and come up with a plan that's best for you.


Doctors don’t know the exact causes of breast cancer. Experts think it may be a combination of things, including your genes, environment, and lifestyle.

You can't inherit a bad copy of the HER2 gene from a parent, and you won’t pass it on to your children.


The most common warning sign of any type of breast cancer is a lump in your breast that feels different from the area around it. That’s true for the HER2-positive type, too.

Other symptoms may include:

  • Breast swelling
  • A change in its shape
  • 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 a growth.


When you find out that you have breast cancer, your doctor will check to see if yours is HER2-positive. She'll probably give you one or more of these tests:

The IHC test uses certain antibodies that identify the HER2 protein in a sample of breast cancer tissue. If there is a lot of it, the cells change color in the sample.

These tests see if there are too many HER2 genes in the cancer cells:

The FISH test uses fluorescent pieces of DNA that stick to the HER2 gene in cells, which can then be counted under a microscope.

The SPOT-Light HER2 CISH and the Inform HER2 Dual ISH tests use stains that color HER2 genes in a tissue sample so they can be counted under a microscope.

Sometimes the results of a single test aren't clear. If that happens, your doctor may order another type.


Questions for Your Doctor

  • How are you sure my cancer is HER2-positive?
  • Where exactly is my cancer?
  • What stage is it?
  • What are my treatment options?
  • What treatment do you think will work best for me?
  • How quickly do I need to start the treatment?
  • How will the treatment make me feel?
  • Is there a clinical trial I should consider?
  • Will I be able to work?
  • Do I need to have my breast removed?
  • Do I need radiation?
  • Do I need chemotherapy?
  • Do I need hormone treatment?
  • Will my insurance cover my treatment?
  • What if my cancer doesn’t respond to the treatment?


Because your breast cancer is HER2-positive, your doctor will treat it a special way.

Along with any chemotherapy treatments you'll get, there are drugs that doctors call “targeted treatments." They block HER2 receptors to help keep your cancer cells from growing.

You may be on this treatment plan for a long time. It lowers the chances that your disease will come back.

If your cancer is hormone-receptor positive, then you may also take hormone therapy.

Taking Care of Yourself

Having breast cancer can be overwhelming. Remember, though: You're in control of your treatment decisions and how you live your life.

These tips can help you stay healthy while you get treatment:

Get the support you need, whether it's information about breast cancer, talking with someone, or practical help with daily tasks. It can all make a huge difference in how you feel. Listen to your body. Exercise can help you feel better, but only when you're up for it.

Stay nourished. If you don’t have much appetite, eat smaller meals every few hours, rather than three big meals.

What to Expect

Many women do well with targeted treatments. Breast cancer of any kind is easier to treat when it’s diagnosed early. If your disease spreads or has comes back, there are still ways to treat it.

Talk with your doctor about whether a clinical trial is a good option for you. These are studies that test treatments that aren’t yet available.


Get Support

The American Cancer Society is a good starting place to find the support you and your family may need throughout your treatment and afterward.

You may want to join a support group. That’s a good way to meet people who know what you're going through, because they’ve been through it, too.

Let your family and friends know how you're feeling. Tell them what they can do to help you. They may want to help but don’t know what to do.

Also, consider talking with a counselor. That could help you handle the emotions that can come with having cancer.

WebMD Medical Reference Reviewed by Michael W. Smith, MD on December 26, 2017




Breastcancer.org: "HER2 Status," "How Triple-Negative Breast Cancer Behaves and Looks,” “Inform HER2 Dual ISH Test,”  “SPoTLight HER2 CISH Test.”

Lab Tests Online: "HER-2/neu."

American Cancer Society: "How is breast cancer diagnosed?" "Treatment of invasive breast cancer, by stage,” “Understanding Your Pathology Report: Breast Cancer,” "Signs and Symptoms of Breast Cancer."

Ithimakin, S. Cancer Research, April 1, 2013.

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