What are estrogen receptor/progesterone receptor (ER/PR) tests?

Estrogen receptor/progesterone receptor (ER/PR) tests are done on samples of your tissue that contain breast cancer cells. The tests check if your cancer cells have estrogen and progesterone receptors (proteins that estrogen and progesterone attach to). The results of the tests are used to help guide breast cancer treatment.

Receptors are special proteins inside or on the surface of cells. They can attach to certain substances in your blood, including estrogen and progesterone. Estrogen and progesterone are hormones (chemical messengers in your bloodstream that control the actions of certain cells or organs). These hormones play key roles in a woman's sexual development and reproductive functions. Men also have these hormones, but in much smaller amounts.

Breast cancer can affect both women and men. If a receptor attaches to estrogen and/or progesterone, the receptor may use that hormone to trigger certain breast cancer cells to grow.

ER/PR tests will show whether there are ER and/or PR receptors on your breast cancer cells. Test results are frequently referred to as the hormone receptor status. The different statuses include:

• ER-positive (ER+): Cancers that have estrogen receptors (ER). Most breast cancers are ER-positive.
• PR-positive (PR+): Cancers that have progesterone receptors (PR)
• Hormone receptor-positive (HR+): Cancers with one or both receptor types.
• HR-negative (HR-): Cancers without ER or PR receptors.

If your hormone receptor status shows you have one or both receptors on your cancer cells, you may respond well to certain treatments.

Other names: ER/PR IHC testing, hormone receptor status, hormone receptor test, ER/PR test

What are they used for?

ER/PR tests are used to guide treatment for breast cancer patients.

Why do I need an ER/PR test?

You may need this test if you've been diagnosed with breast cancer. Knowing your hormone receptor status will help your health care provider decide how to treat it. If you have ER-positive, PR-positive, or HR-positive cancer, medicines that lower hormone levels or stop the hormones from helping cancer to grow can be very effective. If you have HR-negative cancer, these types of medicines won't work for you.

What happens during ER/PR testing?

Your provider will need to take a sample of your breast tissue in a procedure called a breast biopsy. There are may ways to do a biopsy:

There are three main types of breast biopsy procedures. They are usually done on an outpatient basis, which means you go home the same day:

• Fine needle aspiration biopsy uses a very thin needle to remove a sample of breast cells or fluid. The biopsy takes about 15 minutes.
• Core needle biopsy uses a wide needle to remove one or more small tissue samples about the size of a grain of rice. Sometimes a small vacuum probe is used instead of a needle. The device gently suctions some tissue and removes it with a small rotating blade. A core needle biopsy takes between 15 minutes and an hour, depending on how it's done.
• Surgical biopsy (or open biopsy) is surgery to remove all or part of a lump. The biopsy usually takes about an hour.

Biopsies are often done using mammography, ultrasound, MRI, or x-rays to help see exactly where to take the tissue sample. Your procedure will vary depending on which method is used to guide the biopsy, but the general steps are usually the same.

For a fine needle aspiration biopsy or a core needle biopsy:

• Your provider will clean the skin on your breast and give you a shot of medicine to numb the area, so you won't feel any pain. The shot may sting briefly.
• You may be sitting or lying down. If images are used to guide the biopsy, you may lie on your side, back, or belly with your breast over an opening on the table.
• For a fine needle aspiration biopsy, your provider will insert the needle into the biopsy site and remove a sample of cells or fluid. For a core biopsy, a tiny cut may be made to insert a wide needle or a vacuum device. You may feel a little pressure when the sample or samples are removed.
• Pressure will be applied to area until the bleeding stops.
• Your provider will cover the biopsy site with a sterile bandage. If you had a small incision, small strips of medical tape may be used to close the wound.

For a surgical biopsy:

• You'll lie on an operating table. You may have an IV (intravenous line) in your arm or hand that may be used to give you medicine to relax. The skin over the biopsy area will be cleaned.
• To prevent pain, you'll have either:
  • A shot of medicine to numb your breast. The shot may sting briefly.
  • General anesthesia, which is medicine given through an IV to make you sleep.
• When you are numb or asleep, the surgeon will make a small cut in your breast tissue to remove part or all of the lump. In certain cases, tissue around the lump may also be removed. This may help avoid the need for more surgery if cancer cells are found in the lump.
• The cut in your skin will be closed with small strips of medical tape or stitches and covered with a sterile bandage.

The type of biopsy you have will depend on:

• The size and location of the suspicious tissue in your breast
• How many areas of your breast are involved
• How abnormal the tissue looks on a mammogram or other image
• Your general health and preferences

Ask your provider about why you need a biopsy and which type is right for you.

Will I need to do anything to prepare for the test?

Your provider will give you instructions for how to prepare for your biopsy. If you take any blood thinners, including aspirin, you may need to stop taking them before your biopsy. Tell your provider about all the medicines and supplements you take. Don't stop or start taking anything without talking with your provider first.

If you're having general anesthesia, you will probably need to fast (not eat or drink) for several hours before surgery. If you have general anesthesia or medicine to relax, you may be groggy after the procedure, so plan to have someone take you home.

Are there any risks to the test?

It's common to have some bruising and temporary discomfort after a breast biopsy. Possible risks include:

• Infection, which can be treated with antibiotics
• Bleeding

Your provider will give you instructions for how to care for biopsy area and manage any discomfort. If you're having general anesthesia, talk with your provider about how it may affect you. General anesthesia is very safe even for most people with other health conditions.

What do the results mean?

The results will show whether you have a hormone receptor-positive or negative type of cancer.

If your hormone receptor status is positive:

• At least 1% of the cells in your sample have estrogen and/or progesterone receptors.
• The cancer is using either estrogen or progesterone to grow. The higher the levels of receptors, the more effective certain medicines may be in treating your cancer.
• These results may also be called hormone-sensitive, hormone receptor-positive, or HR-positive.

If your hormone receptor status is negative:

• Less than 1% of the cells in your sample have receptors, so those medicines will not be effective.
• These results may also be called hormone insensitive, receptor-negative, or HR-negative.

If you have questions about your results, talk to your provider. They may want to do other tests before making a diagnosis and planning the best treatment for you.

Is there anything else I need to know about ER/PR tests?

HER2 testing is often done at the same time as ER/PR testing to help guide treatment. HER2 is a protein involved in normal cell growth. It also helps certain types of cancer cells grow quickly.  Cancers with large amounts of HER2 protein tend to grow quickly and spread to other parts of the body. Breast cancer cells with higher-than-normal levels of HER2 are called HER2-positive. Certain medicines, called HER2 targeted therapy, can block or slow HER2 proteins and help control these cancers. But these medicines won’t help cancers that don’t have high levels of HER2 proteins. So, HER2 tumor marker testing is necessary to find out if targeted therapy will be helpful.