Here's What to Expect From Your Estrogen Receptor Test

About one in every eight women in the United States will develop an invasive breast cancer, according to the American Cancer Society. Every year, doctors diagnose nearly 290,000 new cases of invasive breast cancer, plus another 51,000 cases of noninvasive (i.e., in situ) breast cancer.

If you have a suspicious lesion that’s found on an exam or through a mammogram, your doctor takes a biopsy and sends it to a laboratory, which examines the tissue for the presence of cancer cells. If cancer cells are found, they’re further tested to determine if the cells have estrogen receptors, progesterone receptors, or both.

At Elite Gynecology, our expert gynecologists, Molly McBride, MD, and Tamara Guichard, MD, help you understand your breast cancer diagnosis and your treatment options. Whether your tumor cells are positive or negative for estrogen and progesterone receptors helps guide your treatment.

Why hormone receptors are important

If your cancer cells have estrogen receptors, that means they respond to signals sent by the hormone estrogen that tell them to grow. If the cancer cells have progesterone receptors, they respond to signals from progesterone that encourage growth. About two out of every three breast cancers test positive for hormone receptors. 

Your tumor cells may have estrogen receptors only, progesterone receptors only, both, or none. If you’re positive for hormone receptors, you may be able to slow or reverse the growth of the tumors with hormone therapy. If your cancer cells don’t have receptors for estrogen or progesterone, then they won’t respond to hormone therapy. 

Even if your cells tested positive or negative on a previous cancer, you should ask for hormone receptor tests on a biopsy that’s taken from a recurrent tumor. Sometimes, even if you were positive in the past, your new tumor is negative, or vice versa. 

What your results mean

Most labs determine the presence and percentage of hormone receptors on cancer cells with an immunohistochemical staining assay, or ImmunoHistoChemistry (IHC). Each lab may analyze the tests slightly differently, so feel free to ask your doctor questions about what the results mean. 

The tests usually give results in three categories:

Percentage of positive cells

The percentage notes how many cells out of every 100 cells stain positive for hormone receptors. A result of 0% means that no cells have receptors. A score of 100% means that they all have receptors. Usually, if your score is 1% or above, the cells are considered hormone-receptor positive and may respond to hormone therapy. 

Allred score

The Allred score is named for a doctor who developed it. The score ranges between 0 and 8. The score accounts for both the percentage of positive cells as well as how intensely those positive cells stain. Those two measurements are combined into a single score. The higher the score, the more intense and greater in number the receptor cells are.

Positive or negative

If your results are “positive” for hormone receptors, your cancer may respond to hormone therapy. If it’s labeled “negative,” you probably don’t have enough hormone receptors on the cancer cells to warrant hormonal treatment. 

About 80% of breast cancers are estrogen-receptor positive (ER+). Approximately 65% are both estrogen-receptor positive and progesterone-receptor positive (PR+). Only 2% are PR+ but estrogen-receptor negative (ER-).

In approximately 25% of cases, the tumors are PR- and ER-. Those tumors won’t respond to hormone therapy.

How your results affect treatment

Hormone therapy either blocks estrogen in the body or blocks its effects on the cancer cells themselves. Hormonal therapy only works on ER+ cells. 

Your doctor may recommend several therapies, such as:

• Aromatase inhibitors (for postmenopausal women) that prevent androgens from becoming estrogens
• Selective estrogen receptor modulators (SERMs) that block estrogen in the cell
• Estrogen receptor downregulators (ERDs) that block estrogen and distort the shape of the receptors

If you’re ER+ or PR+, you may start hormone therapy before surgery, to help reduce the size of your tumors. You may also take hormone therapy afterwards, to reduce the risk of recurrence. You usually take hormone therapy for about five years. 

The earlier breast cancer is caught, the easier it is to cure. Don’t delay a breast cancer screening due to fear. Book your breast cancer screening and well-woman exam today by contacting us at the office nearest you — in Midtown East, Murray Hill, New York City or in Forest Hills, New York — or use our online appointment button.