Key Insights

• Understand how this test reveals your body’s current biological state by showing whether an endometrial tumor expresses estrogen and progesterone receptors, which signals its biology and likely behavior.
• See the exact estrogen receptor (ER) and progesterone receptor (PR) status in tumor tissue to help explain tumor subtype, grade, and potential responsiveness to hormone-based therapies with your care team.
• Learn how factors like tumor histology, grade, menopause status, prior hormonal exposure, and genetics may shape your ER/PR results and what they mean for prognosis.
• Use insights to guide treatment planning with your clinician, including whether hormone-based approaches or fertility-sparing pathways may be considered.
• Track how receptor status changes over time if disease recurs or after treatment to understand adaptation and refine strategy.
• When appropriate, integrate ER/PR findings with related panels such as mismatch repair (MMR), p53, HER2, Ki-67, and molecular profiling to build a complete picture of tumor biology.

What Is an ER/PR Test?

An ER/PR test measures whether endometrial cancer cells carry estrogen receptors (ER) and progesterone receptors (PR). It is performed on tumor tissue from an endometrial biopsy, curettage, or hysterectomy. In the lab, a pathologist uses immunohistochemistry (IHC) to stain the tissue for ER and PR. Results are reported as the percentage of tumor cell nuclei that stain positive and the intensity of staining, often summarized as an Allred score or H-score. Laboratories define their own thresholds for positivity, and your report will clearly state whether each receptor is positive or negative and how strongly it is expressed.

Why this matters: ER and PR status reflects how much a tumor depends on hormonal signaling to grow or respond to therapy. In endometrial cancer, receptor status is linked to tumor subtype, grade, prognosis, and potential benefit from hormone-based treatments. Because IHC can detect even small amounts of receptor protein in cells, it offers a sensitive, objective readout of tumor biology. This information complements core pathology findings to help your care team understand both the current state of the disease and how it may behave over time.

Why Is It Important to Test Your Estrogen and Progesterone Receptors?

Estrogen and progesterone receptors are the “antennae” that let cancer cells sense and respond to hormones. When an endometrial tumor expresses ER and PR, it often behaves differently than a tumor that lacks them. Receptor-positive cancers tend to be more differentiated, grow more slowly, and are more likely to respond to hormone-based strategies that counteract estrogen-driven growth or restore progesterone signaling. Receptor-negative cancers commonly point to more aggressive biology, different histologic subtypes, and the need to prioritize non-hormonal approaches. Testing is especially relevant after a confirmed cancer diagnosis, when planning fertility-sparing care in select early-stage cases, and when evaluating recurrence.

Big picture, ER/PR testing turns a static diagnosis into a more dynamic map of tumor behavior. By measuring a key control system, it helps detect early signals of risk, stratify prognosis, and track adaptation if the cancer returns. Over time, it shows whether the tumor’s “listening” to hormones is turning up, fading, or switching off, which can shape decisions about surveillance and therapy in partnership with your oncologist. The goal is not to pass or fail a lab value, but to understand how your cancer works so that choices are grounded in biology, not guesswork.

What Insights Will I Get From an ER/PR Test?

Your report presents ER and PR as positive or negative, often with a percentage of tumor cell nuclei stained and an intensity score. Many labs use quantitative systems like Allred or H-score to combine percentage and intensity into a single metric, with a lab-defined cutoff for positivity rather than a population “reference range.” In other words, there is no “normal” for ER/PR in cancer tissue; interpretation is based on whether the tumor shows meaningful receptor expression.

When ER and PR are strongly positive, it suggests a tumor more influenced by hormonal signaling, often associated with endometrioid histology, lower grade, and a more favorable prognosis in aggregated data. Lower or absent expression can indicate more aggressive biology or a non-endometrioid subtype, which may guide your team toward different treatment pathways. Context matters. The same percentage can mean different things depending on tumor grade, stage, and molecular profile, and small shifts over time can carry outsized meaning for planning.

The power of the ER/PR test is pattern recognition over time. Viewed alongside MMR status, p53, HER2, Ki-67, and stage and grade, it helps your clinicians see how the tumor is wired and how it changes. Research has linked PR positivity with better response to progestin-based strategies and improved disease-specific outcomes in select settings, though patient selection and tumor biology are key and more research is ongoing. Your results are a signal, not a verdict, and they work best when combined with your history, imaging, and the rest of your pathology report.