Do you know what your breast cancer diagnosis really means? Even more, do you know how your specific type of breast cancer is going to affect you? Read on to get answers to these questions and others.

What to look for in your pathology report

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.

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 status and your HER2 status.

Continue reading to learn more about how HR and HER2 status in breast cancer affects your treatment and your outlook.

What HR-positive means

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

Approximately 80 percent of breast cancers test positive for ER. About 65 percent of those are also positive for PR.

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 drugs designed to affect hormone production.

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

What HER2-negative means

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. These receptors play a role in how healthy breast cells reproduce and repair themselves.

When the HER2 gene isn’t functioning properly, it reproduces too many copies, which leads to overexpression of the HER2 protein. This causes uncontrolled breast cell division and the formation of tumors. This is known as HER2-positive breast cancer.

HER2-positive breast cancer tends to be more aggressive than HER2-negative breast cancer.

How HR and HER2 status affects treatment

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

Surgery, chemotherapy, and radiation are treatment options for all types of breast cancer. Your oncology team will make recommendations based on several other factors, including how far the cancer has spread.

Various drug treatments for HR-positive breast cancer are available, including:

  • selective estrogen-receptor response modulators (SERMs)
  • aromatase inhibitors, which are used only in postmenopausal women
  • estrogen-receptor downregulators (ERDs), some of which are used to treat advanced HR-positive breast cancer
  • luteinizing hormone-releasing hormone agents (LHRHs)
  • megestrol, which is generally used for advanced breast cancer that hasn’t responded to other treatments

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

A more aggressive treatment for premenopausal women with HR-positive breast cancer is surgery to remove their ovaries and stop hormone production.

A number of drugs are available that target the HER2 protein. However, there are no targeted treatment options for HER2-negative breast cancer.

About 74 percent 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.

In general, HR-positive/HER2-negative breast cancer tends to be less aggressive than some other types. It usually responds well to hormonal therapy, particularly when diagnosed and treated in the early stages.

Two drugs are used to treat advanced HR-positive/HER2-negative breast cancer in postmenopausal women:

  • Palbociclib (Ibrance), used in combination with aromatase inhibitors.
  • Everolimus (Afinitor), used in combination with an aromatase inhibitor called exemestane (Aromasin). It’s intended for women whose cancer progressed while using letrozole (Femara) or anastrozole (Arimidex), both aromatase inhibitors.

You can have other treatments, such as chemotherapy and radiation, while using these targeted therapies.

Other things to consider

Learning the basics of HR-positive/HER2-negative breast cancer makes it easier for you and your loved ones to understand your options and cope with your diagnosis.

In addition to HR and HER2 status, a number of other things will factor into your choice of treatment:

  • Stage at diagnosis: Breast cancer is divided into stages 1 through 4 to indicate tumor size and how far the cancer has spread. Cancer is easier to treat in the early stages, before it has the chance to 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 tumor score of 1 to 3. Grade 1 means the cells are close to normal in appearance. Grade 2 means they’re more abnormal. Grade 3 means they bear little resemblance to normal 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. This is because your HR and HER2 status may have changed, which will affect the approach to treatment.

As well, your overall health, including other medical conditions, your age and whether you’re pre- or postmenopausal, and personal preferences will dictate the course of treatment.

Hormonal treatment can make it harder to get pregnant or cause infertility. If you plan on starting a family or adding to your family, talk to your doctor about this before you start treatment.

Cancer treatment will go more smoothly when you ask questions and communicate openly with your oncology team.