Hormone Receptor Status and Breast Cancer

April 10, 2025

This page was reviewed under our medical and editorial policy by Hannah Chang, M.D., assistant professor, and Susan Yost, Ph.D., staff scientist, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte

During the breast cancer diagnosis process, women often discover their hormone receptor (HR) status. It is determined by removing tumor tissue during a biopsy or surgery and examining a sample in the laboratory.

Because hormone receptors may fuel the growth of cancer cells, this information helps to determine the most appropriate treatment.

What Is a Hormone Receptor?

Hormone receptors are proteins in or on the surface of cells that attach to certain hormones found in the blood. Two hormones that women produce — estrogen (ER) and progesterone (PR) — may promote the growth of some breast cancers. About 75% of patients with breast cancer are positive for at least one of these hormone receptors.

An immunohistochemistry (IHC) test is a sensitive laboratory test often used to detect estrogen receptors, progesterone receptors, or both, on cancer cells.

Results of the immunohistochemistry test will help the care team develop the patient’s treatment plan.

Estrogen Receptor Positive

Estrogen receptor-positive breast cancers (ER+) have high levels of estrogen. This female hormone helps breast tumors grow and spread. Between 79% and 84% of all breast cancers are ER+. Surgery and hormone therapy are the most common treatments and have shown significantly positive clinical outcomes.

Progesterone Receptor Positive

Progesterone receptor-positive cancers (PR+) have progesterone receptors on the cancer cells. It is rarely found in patients with ER-negative breast cancer. While short-term survival rates are higher for patients with high PR+ levels, these cancers may return many years later. Low PR levels usually mean that the disease is more aggressive and has a poorer prognosis.

Hormone Receptor Positive

If at least 1% of the tumor’s cells contain estrogen and/or progesterone receptors, the cancer is hormone receptor-positive, suggesting the benefit of hormone therapy treatment.

HR+ breast cancer cells contain either estrogen or progesterone receptors or both. They may be treated with drugs that lower estrogen levels or block estrogen from helping cancer cells develop. These are usually slow-growing cancers with a positive outlook in the short term, but they may sometimes return many years later.

Hormone Receptor Negative

If fewer than 1% of tested cells contain hormone receptors, the cancer will be classified as hormone receptor-negative. Hormone therapy treatment is not beneficial for this type.

These cancer cells have no estrogen or progesterone receptors, so hormone therapy is not indicated. Hormone receptor-negative tumors are more common in women who have not yet gone through menopause. HR- cancers tend to grow faster than others, and if they return, it is usually within the first few years.

How Are Hormone Receptors Used in Breast Cancer Treatment?

Knowing which hormone receptors are present will determine the treatment plan recommended by the cancer care team. Depending on the type of receptors, hormone therapy may block production of those hormones or interfere with their ability to affect the breast cancer cells. A few strategies are used.

Blocking ovarian function: Ovaries are the main source of estrogen in premenopausal women. To reduce estrogen levels, ovaries may be surgically removed or treated with radiation.

Blocking estrogen effects: Doctors use several types of medication to disrupt estrogen’s stimulation of cancer cell growth.

Blocking estrogen production: Drugs called aromatase inhibitors may be used to block the aromatase enzyme activity that is essential to estrogen production.