When you have breast cancer, one of the most important things to know is whether the cancer is at an early stage or if it has spread. Stage, type, size, and location of your tumor all can play a role in your treatment and prognosis.
So can the status of proteins in or on your cancer cells. They’re called receptors, and they respond to certain substances in your body. These receptors affect how your cancer grows and how it responds to certain treatments.
Human epidermal growth factor receptor 2 (HER2) is one of these key receptors. HER2 helps control cell growth in healthy cells. But when cancer cells make too much of it, your cancer is more likely to multiply. If your doctor says your breast cancer is HER2-negative, it means your cancer isn’t making a lot of extra HER2. If your cancer were making extra HER2, it would be HER2-positive.
Breast cancer that’s HER2-negative tends to have a better outlook than those that are HER2-positive, since HER2-negative makes the cancer less aggressive. Most breast cancers are HER2-negative.
Understanding Your HER2 Status
HER2-negative and HER2-positive breast cancers have the same symptoms. Your doctor can’t tell which type you have by examining you. Instead, they’ll run a test on a small piece of your tumor. They’ll get the sample for testing either during a biopsy or in surgery.
Your HER2 status is one of many things that affect how fast your breast cancer will grow. There are other hormone receptors (HR) that respond to hormones in your blood as well. Doctors also sometimes refer to receptors separately as estrogen receptors (ER) and progesterone receptors (PR).
But doctors often talk about all the different receptors together. So your HER2-negative cancer will be either HR-positive/HER2-negative or HR-negative/HER2-negative. If your cancer is negative for HER2 and both types of hormone receptors, it’s called triple negative.
Knowing your breast cancer’s HER2 status -- together with its hormone receptor status -- tells you and your doctors about the biology of the cancer. It helps doctors decide which treatment is best to try first and what options you have if you need to try something else later.
Some breast cancer treatments work by targeting HER2. If your cancer is HER2-negative, your doctor won’t use those therapies. They’ll suggest other options based on how advanced your cancer is and whether it’s positive for hormone receptors. They might also look at other factors, including genetic or other changes in your cancer that could affect how fast it’s likely to grow or spread.
How Common Is HER2-Negative Breast Cancer?
About 4 out of 5 breast cancers don’t have extra HER2. Chances are good that your HER2-negative breast cancer is positive for one or both hormone receptors. Almost 70% of breast cancers are HR-positive/HER2-negative. Only about 10% of them are HR-negative/HER2-negative or triple negative.
Cancers can change over time. If your HER2-negative cancer goes away, then comes back or spreads, your doctor may test it again to see if it’s still negative for HER2.
Treatments for HER2-Negative Breast Cancer
The options for treating HER2-negative breast cancer include:
Surgery and/or radiation. If your HER2-negative cancer is caught early, a surgeon may be able to remove it completely. Your doctor might also recommend radiation before or after surgery.
Endocrine therapy. If your HER2-negative cancer is positive for hormone receptors, your doctor might suggest endocrine (hormone) therapy. The goal of endocrine therapy is to lower the amount of hormones in your system. This helps because hormones can make HR-positive breast cancer grow. By reducing how much estrogen or progesterone your body makes, this treatment may slow or shrink the tumor.
Chemotherapy. For HR-positive/HER2-negative breast cancer, you might have chemotherapy along with endocrine therapy. That depends on your cancer’s stage, grade, and other features. Adding chemo can lower the risk that your cancer will come back. But depending on your age and health, the benefits of chemo might not outweigh the risks. Talk with your doctor to see what makes the most sense for you. If your HER2-negative cancer is also negative for hormone receptors (triple negative), you may have surgery before or after chemo.
Immunotherapy. If your HR-negative/HER2-negative (triple negative) breast cancer is advanced and has another protein called PD-L1, immunotherapy might be an option. Immunotherapy uses your own immune system to fight cancer. About 20% of triple-negative breast cancers have PD-L1.
Prognosis for HER2-Negative Breast Cancer
The most important factor in your breast cancer prognosis is whether doctors caught the cancer before it spread too far. If your HER2-negative cancer is only in your breast, your 5-year relative survival rate is about as good as that of someone without breast cancer. That’s especially true if your cancer is positive for hormone receptors.
Triple-negative breast cancer is harder to treat because you can’t use medicines that work through HER2 or endocrine therapy. This type also tends to be more aggressive.
The National Cancer Institute gives 5-year relative survival rates for breast cancer based on how far the disease has spread. If you have HR-positive/HER2-negative breast cancer -- the most common type -- your chances of surviving for 5 years relative to women who don’t have breast cancer is:
- 100% if your cancer is localized (confined to one breast)
- 90% if your cancer is regional (spread to nearby lymph nodes)
- 31% if your cancer is distant (spread to other parts of the body)
If your breast cancer is negative for both HER2 and hormone receptors (triple-negative), your 5-year relative survival rate is:
- 91% if it’s localized
- 65% if it’s regional
- 12% if it’s distant
These numbers are only averages. Your personal outlook depends on many things, including how your cancer responds to treatment and how healthy you are otherwise. If your HER2–negative breast cancer is more advanced, ask your doctor whether you should get other tests to help guide your treatment.
