HER2+ Breast Cancer: What It Is + How It’s Treated

This subtype accounts for 1 in 5 breast cancers in women.

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When diagnosing breast cancer, each patient’s individual disease can be categorized in a number of ways, one of which being something called receptor status. This refers to specific proteins on the surface of cells that “receive” things (such as hormones) to fuel the growth of the cancer.

“Think of [receptors] as little baseball mitts that sit on the surface of the cell,” says Amy Tiersten, MD, hematologist and oncologist at Mount Sinai Hospital in New York City. There are three types of receptors that could potentially be on a breast cancer cell: estrogen, progesterone, and HER2/neu.

What Is HER2-Positive Breast Cancer?

HER2/neu is a protein that helps in cell growth, and you can find them on the surface of all breast cells, according to the American Cancer Society (ACS). While all women have them, some women develop an overexpression of HER2/neu, which helps fuel the growth and spread of the cancer.

When breast cancer is fueled by an overexpression of HER2/neu, this is called HER2-positive breast cancer. This subtype accounts for about 20 percent of breast cancer cases in women, according to ACS.

If the cancer cells do not have an overexpression of the HER2/neu protein, this is known as HER2-negative. This might mean the breast cancer cells have hormone receptors (hormone receptor-positive breast cancer) or they have none of the receptors (triple-negative breast cancer). Learn more about the different subtypes of breast cancer receptor status here.

Treatment for HER2-Positive Breast Cancer

Knowing the receptor status of an individual’s breast cancer is crucial, since many breast cancer treatments are catered toward the receptor status. This is especially useful for HER2-positive breast cancer, since women with this subtype may be candidates for targeted therapy, which has been shown to be extremely effective.

Targeted therapy gets its name because it targets specific gene or protein abnormalities on cancer cells. In the case of HER2-positive breast cancer, targeted therapy is a class of drugs that target the HER2 protein to find and attack cancer cells.

Compared to chemotherapy, targeted therapy is much more precise in how it attacks the cancer cells, and therefore causes much fewer side effects. That said, targeted therapy is sometimes used in combination with chemotherapy to improve outcome further.

The advances in targeted therapy for breast cancer has greatly improved cure rates for HER2-positive breast cancer, which has traditionally been known as an aggressive, fast-spreading cancer.

“Nowadays, it’s considered a good thing to have a HER2-positive breast cancer [compared to other types] because we have incredibly effective targeted antibodies to that HER2 protein,” says Dr. Tiersten. “It really is a time to be very hopeful about being able to offer patients new drugs that vastly improve the outcome of treatment for HER2-positive breast cancer.”

Learn more about how different subtypes of breast cancer are treated here.