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Estrogen Receptor, Progesterone Receptor Tests
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Estrogen Receptor, Progesterone Receptor Tests

ER/PR tests determine if breast cancer cells have hormone receptors, which helps guide the selection of effective cancer treatments.

Overview

Estrogen receptor (ER) and progesterone receptor (PR) tests are performed on breast cancer tissue samples. Receptors are proteins that can attach to hormones; if cancer cells have these receptors, they may use estrogen or progesterone to grow.

Results define your hormone receptor status:

  • ER-positive (ER+): Cancer cells have estrogen receptors.
  • PR-positive (PR+): Cancer cells have progesterone receptors.
  • Hormone receptor-positive (HR+): Cancer cells have one or both receptor types.
  • HR-negative (HR-): Cancer cells lack both receptors.

Why do I need an ER/PR test?

Knowing your hormone receptor status is essential for treatment planning. If your cancer is HR-positive, medications that lower hormone levels or block their effects can be highly effective. These medications are not effective for HR-negative cancers.

What happens during testing?

A tissue sample is obtained via a breast biopsy. Common methods include:

  • Fine needle aspiration biopsy: Uses a thin needle to remove cells or fluid.
  • Core needle biopsy: Uses a wide needle or vacuum device to remove small tissue samples.
  • Surgical biopsy: An outpatient procedure to remove part or all of a lump.

Biopsies are often guided by imaging (mammography, ultrasound, or MRI). You may receive local anesthesia to numb the area or general anesthesia for surgical biopsies.

Preparation and Risks

Inform your provider about all medications and supplements, especially blood thinners. If you are undergoing general anesthesia, you will likely need to fast beforehand and arrange for someone to drive you home. Common risks include temporary bruising, discomfort, bleeding, or infection.

What do the results mean?

  • Positive status: At least 1% of cells have receptors. The cancer is hormone-sensitive, and hormone-blocking therapies may be effective.
  • Negative status: Less than 1% of cells have receptors. Hormone-blocking therapies will not be effective.

Additional Information

HER2 testing is often conducted alongside ER/PR tests. HER2-positive cancers have high levels of the HER2 protein and may respond to targeted therapies designed to block that protein's growth-promoting effects.

Frequently Asked Questions

Results typically take 3 to 7 business days, though this can vary by laboratory. The tissue sample must be processed, stained with specific antibodies, and reviewed by a pathologist under a microscope. If the biopsy was done as part of a larger surgical procedure, results may take slightly longer as the lab processes multiple tissue sections.
Not necessarily. While hormone receptor-positive cancers are often slower-growing and more responsive to endocrine therapy, they can still be aggressive depending on other factors like tumor grade, size, and Ki-67 proliferation index. The positive status is primarily a treatment marker, indicating that hormone-blocking drugs will be effective, rather than a guarantee of a milder disease course.
If your cancer is ER and PR negative, hormone therapy will not work, so treatment focuses on other targets. Doctors often test for HER2 status; if HER2-positive, targeted therapies like trastuzumab are used. If the cancer is triple-negative (ER-, PR-, HER2-), treatment usually involves chemotherapy, immunotherapy, or PARP inhibitors if specific genetic mutations are present.
Yes, receptor status can evolve. Some cancers that are initially ER-positive may become ER-negative after treatment, a phenomenon known as receptor conversion. This is why doctors may recommend repeat biopsies or liquid biopsies if the cancer recurs or metastasizes, to ensure the current treatment plan still targets the active receptors.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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