Progesterone receptor assay

ALSO KNOWN AS: PgR assay, hormone-response assay

DEFINITION: A progesterone receptor assay is an immunoassay performed on sections from breast tumors removed during surgery or on small samples obtained with core needle biopsy.

Cancers diagnosed: Hormone-responsive breast cancer, ductal carcinoma in situ

Why performed: A progesterone receptor assay is used to determine whether a cancer is likely to respond to hormonal therapy.

Patient preparation: The assay is performed on sections of breast tumors removed during surgery or by needle biopsy. For needle biopsy, patients are usually asked not to use powder, deodorant, or perfume on the day of the biopsy.

Steps of the procedure: Tumors removed during surgery are fixed and stained, and then they are examined by a pathologist to determine whether the cells of the tumor express receptors for progesterone. For core needle biopsy, the patient is either upright or lying on her stomach. A local anesthetic is used to numb the breast, and a needle, which may be guided by X-ray imaging, is inserted into the breast mass. Samples of the mass are aspirated into the needle and then sent to a pathologist, who will stain the samples for the assay.

After the procedure: After surgery, the physician will give the patient specific instructions about activities. Patients can usually resume regular activity immediately after a needle biopsy.

Risks: For needle biopsy, the biopsied breast may occasionally show mild bruising.

Results: The progesterone receptor is a member of the steroid receptor superfamily of nuclear receptors. The steroid hormone progesterone binds to the receptor in the cell and regulates the expression of genes involved in growth and cell division. Expression of progesterone (PgR) or estrogen (ER) receptors in cancer cells indicates that they will respond to signals that inhibit their growth and division, including drugs that block signaling by estrogen and progesterone. The results are presented as positive or negative based on the number of hormone-responsive cells. A positive result, particularly in early-stage cancers that are both ER- and PgR-positive, suggests that the cancer will likely respond to hormonal (endocrine) therapies and generally signals a favorable prognosis. Such therapies may include removing the ovaries in premenopausal women, treating with an antiestrogen drug such as tamoxifen, or treating with an aromatase inhibitor to block the synthesis of estrogen by the body. A negative result on the progesterone receptor assay indicates that other types of treatments should be pursued.

Advances continue in using progesterone receptor assays, including the standardization of immunohistochemistry among organizations, such as the American Society of Clinical Oncology and the College of American Pathologists. Another update created a new reporting category called ER Low Positive for breast cancers, in which 1-10 percent of cells stained positive for estrogen receptor. Other advances involving progesterone receptor assays include testing other biomarkers with them and integrating positron emission tomography (PET) scans.

Bibliography

Allison, Kimberly, et al. “Estrogen and Progesterone Receptor Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Guideline Update.” Archives of Pathology and Laboratory Medicine, vol. 144, no. 5, 2020, pp. 545-563. Archives of Pathology and Laboratory Medicine, meridian.allenpress.com/aplm/article/144/5/545/427509/Estrogen-and-Progesterone-Receptor-Testing-in. Accessed 1 July 2024.

Bardou, V.-J. "Progesterone Receptor Status Significantly Improves Outcome Prediction over Estrogen Receptor Status Alone for Adjuvant Endocrine Therapy in Two Large Breast Cancer Databases." Journal of Clinical Oncology, vol. 21.10, 2003, pp. 1973–979.

Bartlett, J. M. S., et al. "Estrogen Receptor and Progesterone Receptor as Predictive Biomarkers of Response to Endocrine Therapy: A Prospectively Powered Pathology Study in the Tamoxifen and Exemestane Adjuvant Multinational Trial." Journal of Clinical Oncology, vol. 29.12, 2011, pp. 1531–538.

“Breast Cancer Hormone Receptor Status.” Breastcancer.org, 12 Oct. 2023, www.breastcancer.org/pathology-report/hormone-receptor-status. Accessed 1 July 2024.

“Breast Cancer Hormone Receptor Status - Estrogen Receptor.” American Cancer Society, 8 Nov. 2021, www.cancer.org/cancer/types/breast-cancer/understanding-a-breast-cancer-diagnosis/breast-cancer-hormone-receptor-status.html. Accessed 1 July 2024.

"Estrogen and Progesterone Receptor Testing for Breast Cancer." American Society of Clinical Oncology, 13 Jan. 2020, www.cancer.net/research-and-advocacy/asco-care-and-treatment-recommendations-patients/estrogen-and-progesterone-receptor-testing-breast-cancer. Accessed 1 July 2024.

Shahab, Muhammad, et al. "Targeting Human Progesterone Receptor (PR), through Pharmacophore-based Screening and Molecular Simulation Revealed Potent Inhibitors against Breast Cancer." Scientific Reports, vol. 14, no. 1, 2024, pp. 1-16, doi.org/10.1038/s41598-024-55321-0. Accessed 1 Jul. 2024.

Stavreva, Diana A., et al. "Novel Biosensor for High-throughput Detection of Progesterone Receptor-interacting Endocrine Disruptors." Scientific Reports, vol. 14, no. 1, 2024, pp. 1-14, doi.org/10.1038/s41598-024-55254-8. Accessed 1 Jul. 2024.

“Tumor Markers.” SEER Training, 4 Mar. 2024, training.seer.cancer.gov/staging/sources/markers.html. Accessed 1 July 2024.