HER2-negative breast cancer: Understanding your diagnosis

Date Updated: 06/13/2026

By Mayo Clinic Staff

A HER2-negative breast cancer diagnosis can feel confusing and overwhelming at first. People with this diagnosis often have many questions about this cancer and how it is treated.

Breast cancer begins as a growth of cells in the breast tissue. Breast cancer starts when something changes the DNA inside cells in the breast tissue. A cell's DNA holds the instructions that tell a cell what to do. In healthy cells, the DNA gives instructions to grow and multiply at a set rate. The instructions tell the cells to die at a set time. In cancer cells, the DNA changes give different instructions. The changes tell the cancer cells to make many more cells quickly. The cancer cells might form a mass called a tumor. The tumor can grow to invade and destroy healthy body tissue.

Breast cancers, including HER2-negative breast cancer, are often grouped into types based on the results of tests on the cancer cells. Lab tests can show whether the cancer cells use hormones such as estrogen or progesterone or a protein called human epidermal growth factor receptor 2 (HER2) to help them grow.

Whether the cancer uses one, all or none of these determines the cancer type. The types, including HER2 results, will give your healthcare team important clues on how to treat the cancer.

What do IHC and FISH testing mean?

Immunohistochemistry (IHC) is a test that stains a tumor to see how much HER2 protein is on the surface of the cancer cells.

Fluorescence in situ hybridization, (FISH or ISH) is a test that looks for extra copies of the HER2 gene.

The results of IHC and FISH tests show if the cancer is HER2-positive, HER2-negative, HER2-low or HER2-ultralow.

What does a HER2 result mean on your pathology report?

Healthcare professionals take a sample of your cancer tissue from a biopsy or surgery and test it to see whether the cancer cells have the HER2 protein, extra copies of the HER2 gene, or both.

If the test finds extra HER2 in the cancer cells or extra copies of the genes that make HER2, the cancer is called HER2-positive. Healthy breast cells make some HER2, but the cancer cells can make a lot more.

If the test does not find HER2 in the cancer cells or extra copies of the genes that make HER2, the cancer is called HER2-negative.

If the tests find a low level of HER2 but not enough to be considered HER2-positive, the cancer is called HER2-low or HER2-ultralow.

Knowing if hormones such as estrogen or progesterone are fueling the growth of cancer cells is also important. If the test finds these hormones, the cancer is called hormone receptor (HR)-positive. If the test does not find these hormones, it is called HR-negative.

Healthcare professionals typically use medications in their treatment plans for people who have cancer fueled by hormones and HER2. There are also newer medications now available for people with HER2-low and HER2-ultralow cancer.

Is there more than one type of HER2-negative breast cancer?

HER2-negative breast cancer is not one condition. It includes two main types:

HR-positive and HER2-negative breast cancer. A HR-positive/HER2-negative result means the cancer cells do not have HER2, and they use estrogen or progesterone or both to help them grow. That result may be listed as HR+/HER2- in your report. The pathology report also may mention a subtype of the HR-positive/HER2-negative result. These subtypes are called luminal A and luminal B. Luminal A subtypes typically have a high amount of estrogen and progesterone hormones and grow slower. Luminal B subtypes have a lower amount of estrogen and progesterone hormones and typically grow faster.

Triple-negative breast cancer (TNBC). This means the cancer cells are negative for estrogen, progesterone and HER2.

How is HER2-negative different from HER2-positive breast cancer?

HER2-positive breast cancers often tend to grow quickly and are typically aggressive. Cancers that are HER2-positive and HR-positive are called triple-positive cancers. There are specialized medicines to treat these cancers that lower hormone levels and target HER2.

HER2-negative breast cancer may grow fast or slow depending on the subtype you have. Healthcare professionals can use certain medications if there is some HER2 in the cancer cells to target. Treatment will be described in more detail later in this article.

What does it mean if the cancer is HER2-negative but is also hormone receptor (HR)- positive?

This means the tests on the cancer cells did not find the HER2 protein, but they found proteins called receptors for either estrogen or progesterone hormones or both. In this case, healthcare professionals may use treatments such as endocrine blocker therapy, also called endocrine therapy, to target hormones on the cancer cells.

Is HER2-negative breast cancer the same as triple-negative breast cancer?

Triple-negative (TNBC) is a type of HER2-negative breast cancer.

TNBC means the cancer cells do not have HER2 protein, or estrogen or progesterone hormone receptors.

Some types of HER2-negative breast cancer are considered HR-positive. This means they have either estrogen and progesterone hormone receptors or both.

Does HER2-negative breast cancer cause different symptoms compared with other types of breast cancer?

HER2-negative breast cancer does not have its own set of symptoms. The symptoms are like breast cancer symptoms in general. These may include:

A breast lump or thickened area of skin that feels different from the surrounding tissue.
A nipple that looks flattened or turns inward.
Changes in the color of the breast skin. This may be a shade of red, purple or brown depending on your skin color.
Change in the size, shape or appearance of a breast.
Changes to the skin over the breast, such as skin that looks dimpled or looks like an orange peel.
Peeling, scaling, crusting or flaking of the skin on the breast.

How is HER2-negative breast cancer staged?

Staging is a way to describe the size of the cancer and whether it has spread from where it started. Information used in staging includes:

The size of the cancer in the breast.
Whether cancer cells have spread to the lymph nodes or other parts of the body.
The cancer's grade. A cancer's grade is a number that tells the healthcare team how different the cancer cells look from healthy cells.
The cancer's hormone receptor HR status. For example, if it is estrogen- or progesterone-positive.
The cancer's HER2 status.
The presence of certain genes that might affect impact treatment options.
Other information that may become available after the cancer is removed during surgery.

A type of staging called clinical prognostic staging happens after all the tests on your biopsy sample are complete. At this point your care team knows your cancer grade, HR status and HER2 status. The prognostic staging process tells your care team more about whether the cancer responds to medical treatment. It helps the team choose the first treatment and understand your prognosis.

TNBC is typically fast-growing. It is more likely to spread to nearby breast tissue and lymph nodes before it is found.

The stages of breast cancer can be confusing and complicated. There are several types of stages, and they consider different factors. Ask your healthcare team to explain your stage and what it means for your treatment.

How is HER2-negative breast cancer treated?

Treatment for HER2-negative breast cancer depends on the subtype and the stage. It often involves several steps. Treatments typically include surgery and medicines, such as chemotherapy and immunotherapy. Other treatments might include radiation therapy and targeted therapy.

TNBC

The HER2-negative subtype TNBC is typically treated with a combination of surgery and whole-body treatment. This most often includes chemotherapy and sometimes immunotherapy. This is because the medicines used to treat the HR-positive/HER2-negative breast cancer subtype do not work on TNBC.

If the cancer in the breast is small, treatment may start with a lumpectomy or mastectomy. If the cancer in the breast is larger, healthcare professionals often use chemotherapy and, sometimes, immunotherapy before surgery. Treatment before surgery is called neoadjuvant therapy. The medicines help to shrink the cancer and make it easier to remove. Using medicine first also gives the healthcare team a chance to see how well the treatment works. This helps the care team make decisions about what treatment to do next to shrink the cancer.

When cancer spreads, it's called metastatic cancer. If TNBC spreads to distant parts of the body, treatment usually focuses on slowing the growth of the cancer and managing symptoms. Treatment often starts with chemotherapy or other medicines. It may include surgery, radiation therapy and new options being tested in clinical trials.

HR-positive/HER2-negative breast cancer

The HER2-negative subtype HR-positive/HER2-negative breast cancer is typically treated with surgery if the cancer is in its early stages. Medicines called estrogen blockers also are usually given to lower the chance of the cancer coming back. If cancer comes back, that is called a recurrence.

If HR-positive/HER2-negative cancer spreads to distant parts of the body, treatment usually focuses on slowing the growth of the cancer and managing symptoms. Treatment often starts with chemotherapy or other medicines.

Can HER2-negative breast cancer affect pregnancy or fertility?

Some treatments used for HER2-negative breast cancer, such as chemotherapy, may affect the ability to get pregnant after treatment. If you think you may want to have children in the future, talk about this with your healthcare team. Your team may refer you to a fertility specialist, who can explain your options. These might include freezing eggs, freezing embryos and other ways to preserve fertility.

Breast cancer can be diagnosed during pregnancy. In that setting, testing and treatment are personalized to protect both the mother and the baby.

What does HER2-negative mean for prognosis?

Cancer prognosis describes how likely it is that a cancer can be successfully treated or cured. The prognosis is based on the details of your cancer, as well as your overall health.

The type of HER2-negative breast cancer you have often affects the prognosis. For example, having triple-negative breast cancer (TNBC) limits treatment options, since this type of cancer will not respond to treatments such as hormone blocker therapy that target estrogen and progesterone hormone levels. TNBC also will not respond to treatments that target the HER2 protein.

Compared with other types of breast cancer, TNBC is more likely to be diagnosed at a later stage. The cancer often has grown large or spread to the lymph nodes. This also makes treatment more challenging.

HR-positive/HER2-negative breast cancer usually grows more slowly than TNBC and has more treatment options. The kind of luminal subtype found in HR-positive/HER2-negative breast cancer also may affect prognosis. A review of the luminal subtypes found that HR-positive/HER2-negative breast cancer with luminal A had a better prognosis compared with HR-positive/HER2-negative breast cancer with luminal B. That is because luminal A has more hormones to target with hormone-blocking medicines.

If you want to better understand your personal prognosis, talk with your healthcare team. Your team can walk you through the factors they consider and explain what those mean for you.