Why Hormone Receptors Matter in Breast Cancer

The hormones in your body that launched you into puberty and controlled your monthly period can play a role in breast cancer.

Most breast cancers -- about 70% -- are sensitive to the hormones estrogen or progesterone. These tumors have a sort of biological on-off switch called a hormone receptor. Estrogen and progesterone can flip these switches "on" and quicken the cancer cells' growth.

Your doctor will check to see if your tumor has hormone receptors. If it does, they may call it "hormone-receptor positive," “ER-positive,” or “PR-positive.”

For advanced cases, your doctor may want to repeat these tests after a while to see if the disease has changed. It may respond differently to hormones than before. The results will help your doctor find the best treatment at any stage.

How It's Different

Compared with other types of breast cancer, hormone-receptor-positive ones, also called HR-positive, tend to:

• Grow more slowly
• Respond better to hormone therapy
• Have a better outlook (prognosis)

Testing for Hormone Receptors

In advanced cancer, your doctor will take a small part of the cancer that has spread to your lymph nodes, liver, or other areas of your body. They may use a very fine needle or get the tissue during surgery. Lab tests will show if the disease has hormone receptors.

If you're taking hormones, you may need to stop before getting the test.

Cancer cells may have:

• Estrogen receptors only. Your doctor will call these “ER-positive” or “ER+” cancers.
• Progesterone receptors only. These are “PR-positive,” or “PR+.”
• Both estrogen and progesterone receptors, which doctors call “hormone- responsive”
• Neither estrogen or progesterone receptors, called “hormone negative” or “HR-"

What Hormone Receptor Test Results Mean

Your treatment choices may depend partly on the test results.

In the lab report, you may see one of these:

A simple "positive" or "negative" description. If it says “positive,” that means your cancer is sensitive to hormones. If it says “negative,” it’s not. The “positive” and “negative” don't mean better or worse -- it’s just about the tumor.

A percentage of cells out of 100 that have hormone receptors. A score of 0% means no cells have receptors. 100% means all cells have them.

An "Allred score" between 0 and 8. This tells how many cells are HR-positive as well as their "intensity" (how well they show up in the lab tests).

Labs use different cutoff points to tell if the cancer is HR-positive. Ask your doctor to explain what they mean for you.

How It Affects Your Treatment

If you have an HR-positive breast cancer, your doctor may prescribe drugs that target certain hormones your body makes. Doing that makes it harder for cancer cells to survive.

There are different kinds of hormone treatments. Some lower the amount of those hormones that your body makes. Others block the effects of hormones in breast tissue or in other places where the cancer may have spread.

In general, the more receptors you have and the greater their intensity, the more likely it is that hormone treatments will work.

If your cancer is only “ER-positive” (sensitive to estrogen) or only “PR- positive” (sensitive to progesterone) -- not both -- it may still respond to hormone treatments.

If your disease is both ER-negative and PR-negative, hormone therapy is unlikely to work. Another type of treatment may work better. Your doctor will find the best options with the fewest side effects and talk with you about the benefits and risks of each.

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