The hormones in your body that controlled the growth of your hips as a teen, your monthly period, and even hot flashes can play a role in breast cancer.
That's because some breast cancer cells have a sort of biological on-off switch, called a hormone receptor. Two female hormones can flip these switches "on" and quicken the cancer cells' growth. They are estrogen and progesterone.
Tests can show if your cancer has hormone receptors.
For advanced breast cancer, your doctor may want to repeat these tests after a while to see if your cancer has changed. It may respond differently to hormones than before. Test results will help your doctor find the best treatment at any stage.
HR-Positive Cancer Is Common
About 2 out of 3 breast cancers have hormone receptors. They're more common in older than younger women.
Compared with other types of breast cancer, hormone-receptor-positive breast cancers, called HR-positive cancers, tend to:
- Grow more slowly
- Respond better to hormone therapy
- Have a better outlook (prognosis)
Testing for Hormone Receptors
In advanced cancer, this involves testing a small portion of the cancer that has spread to the lymph nodes, the other breast, liver, or other areas of the body.
The tissue may be removed during surgery or during a needle or surgical biopsy.
If you are on hormones, you may need to stop taking them before the testing.
Most labs use a stain process, which makes the receptors show up. Cancer cells may contain:
- Estrogen receptors only. These are ER-positive (ER+) cancers.
- Progesterone receptors only. These are PR-positive (PR+) cancers.
- Both estrogen and progesterone receptors
- Neither estrogen or progesterone receptors, called HR negative (HR-)
What Hormone Receptor Test Results Mean
In the lab report, you may see one of these:
- A simple "positive" or "negative" description
- 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 receptors.
- 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 when stained).
Labs use different cutoff points to tell if the cancer is HR-positive. Ask your doctor to explain what they mean for you.
Your treatment choices may depend partly on these tests.
Do you have an HR-positive breast cancer? If so, hormone therapy can make it harder for cancer cells to survive. These types of drugs can lower the hormones your body makes. Some kinds block the effects of hormones in breast tissue.
In general, the more receptors present and the greater their intensity, the greater the odds that hormone treatments will work.
If your cancer is only ER-positive or only PR-positive -- not both -- it may still respond to hormone treatments. However, the response may not be as strong.
If your cancer 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 treatment with the fewest side effects for your type of cancer.