Each type of breast cancer requires its own approach to treatment. The information in your pathology report will help guide your treatment goals and options. Two important items on the report will be your HR and HER2 status.

When you have a biopsy for a breast tumor, the pathology report tells you a lot more than whether it’s cancerous or not. It provides crucial information about the makeup of your tumor.

This is important because some types of breast cancer are more aggressive than others, meaning they grow and spread faster. Targeted treatments are available for some types but not for all.

HR is short for hormone receptor. Breast tumors are tested for estrogen receptors (ER) and progesterone receptors (PR). Each status appears separately on your pathology report.

Approximately 80% of breast cancers test positive for ER. Most breast cancers that test positive for ER also test positive for PR, according to the National Cancer Institute.

You can test positive for ER, PR, or both. Either way, it means that hormones fuel your breast cancer. It also means that your treatment can include medications that affect hormones.

It’s also possible to test negative for both hormone receptors. If that’s the case, hormones do not fuel your breast cancer, so hormone therapy wouldn’t be effective.

HER2 is short for human epidermal growth factor receptor 2. In a pathology report, HER2 is sometimes called ERBB2, which stands for Erb-B2 receptor tyrosine kinase 2.

HER2 is a gene that produces HER2 proteins or receptors. When the HER2 gene isn’t functioning properly, it reproduces too many copies.

Overexpression of the HER2 protein causes uncontrolled breast cell division and the formation of tumors. This is known as HER2-positive breast cancer.

If breast cells do not have abnormal levels of HER2 proteins, breast cancer is considered HER2-negative.

HER2-positive breast cancer tends to be more aggressive than HER2-negative breast cancer. However, current therapies targeting the HER2 receptor are so effective that many doctors find treating it easier.

Your treatment plan will be based on both your HR status and your HER2 status.

Hormonal therapy is usually recommended as the first-line treatment for HER2-negative advanced breast cancer that’s HR-positive.

HR-positive breast cancer treatments

  • selective estrogen-receptor response modulators (SERMs)
  • aromatase inhibitors
  • estrogen-receptor downregulators (ERDs), some of which are used to treat advanced HR-positive breast cancer
  • luteinizing hormone-releasing hormone agents (LHRHs)
  • removal of the ovaries (oophorectomy)

Some of these drugs lower hormone levels. Others block their effect. The drugs are also used to help prevent cancer from recurring.

About 70% of all breast cancers are both HR-positive and HER2-negative.

Breast cancer that starts in the luminal cells that line the mammary ducts is called luminal A breast cancer. Luminal A tumors are usually ER-positive and HER2-negative.

Advanced HR-positive/HER2-negative breast cancer treatments

  • Palbociclib (Ibrance), ribociclib (Kisqali), or abemaciclib (Verzenio) are combined with aromatase inhibitors.
  • Everolimus (Afinitor) is combined with an aromatase inhibitor called exemestane (Aromasin). It’s intended for those whose cancer progressed while using letrozole (Femara) or anastrozole (Arimidex).
  • Alpelisib (Piqray) blocks a form of the PI3K protein in cancer cells.
  • Fulvestrant (Faslodex) targets the estrogen receptor to inhibit cancer cell growth.
  • Tamoxifen is a SERM that can inhibit the effects of estrogen in the breast tissue.
  • Toremifene (Fareston) is a SERM that’s sometimes used to treat advanced breast cancer after menopause.
  • Goserelin (Zoladex) and leuprolide (Lupron) stop estrogen production.
  • Monoclonal antibodies, including trastuzumab (Herceptin) and pertuzumab (Perjeta), attach to the HER2 protein to help prevent cancer cells from growing.
  • Antibody-drug conjugates (ADC), including ado-trastuzumab emtansine (Kadcyla) and fam-trastuzumab deruxtecan-nxki (Enhertu), attach to the HER2 protein on cancer cells, bringing any chemotherapy directly to it.
  • Kinase inhibitors, including lapatinib (Tykerb), neratinib (Nerlynx), and tucatinib (Tukysa), attempt to slow cell growth by blocking growth signals from a type of protein called kinase.

Your oncology team will make recommendations based on several factors:

  • Stage at diagnosis: Breast cancer is divided into stages 1–4 to indicate tumor size and how far the cancer has spread. Cancer is easier to treat in the early stages before it can spread. Stage 4 means the cancer has reached distant tissues or organs. This is also called advanced or metastatic breast cancer.
  • Tumor grade: Breast tumors have a grade of 1–3. Grade 1 means the cells are close to the expected appearance. Grade 2 means they’re more abnormal. Grade 3 means they bear little resemblance to healthy breast cells. The higher the grade, the more aggressive the cancer.
  • Whether this is a first cancer or a recurrence: If you’ve previously been treated for breast cancer, you’ll need a new biopsy and pathology report. Your HR and HER2 status may have changed.

Your overall health — including other medical conditions, age, and whether you’re pre- or postmenopausal — will also dictate the course of treatment.

Some breast cancer treatments can affect your fertility. Hormonal treatment can also harm a developing pregnancy. If you are or plan to become pregnant, talk with your doctor about this before you start treatment.

Breast cancer diagnosis typically involves a combination of imaging tests, such as mammograms and ultrasounds, and biopsy procedures to confirm the presence of cancerous cells.

Your outlook depends on several factors, including the stage, specific subtype, tumor grade, and whether the lymph nodes are involved.

Treatment options may include surgery, chemotherapy, radiation, and hormone therapy. Multiple treatments may be used in combination to achieve the best possible outcome.