Norm of Estradiol Receptor and Progesterone Receptor in Breast Cancer
|Negative||<6 fmol/mg cytosol protein||<6 nmol/kg cytosol protein|
|Borderline||6–10 fmol/mg cytosol protein||6–10 nmol/kg cytosol protein|
|Positive||>10 fmol/mg cytosol protein||>10 nmol/kg cytosol protein|
Usage of Estradiol Receptor and Progesterone Receptor in Breast Cancer
Used to predict response to hormonal therapy in clients with breast cancer.
Description of Estradiol Receptor and Progesterone Receptor in Breast Cancer
Estrogen receptors and progesterone receptors are intracellular proteins that specifically bind estrogens and progesterones. The establishment of receptor status in clients with breast cancer is crucial because the receptors are the most predictive factor for the response to hormonal therapies for primary and metastatic breast cancer. They are the only tumor markers recommended for routine clinical use in breast cancer by the Tumor Marker Panel of the American Society of Clinical Oncology. Clients whose tumors express the estrogen and progesterone receptors respond more often and have longer disease-free periods and overall survival rates when treated with hormonal therapy. Although receptor status is important in determining which clients are likely to benefit from endocrine therapy, estrogen and progesterone receptor status is only a weak predictor of long-term relapse and mortalities and is not to be used alone to assign a client to a particular prognostic grouping. It should be noted that breast cancers that are initially hormone dependent might progress to a hormone-independent form, despite the continued expression of the receptor. This may limit the long-term usefulness of the hormonal therapies. Historically these receptors were measured by means of biochemical assays, but there are now highly specific monoclonal antibodies and immunohistochemical techniques available to assess estrogen and progesterone receptor status. When receptor status is determined using biochemical assays, sampling error may occur if the sample does not contain enough tumor, if there is significant desmoplastic response, or if there is a delay in the processing of the specimen. A value of less than 3 fmol/mg is considered negative when measured by the biochemical assay. Using the immunocytochemical assay, which measures the concentration of receptors by staining them with monoclonal antibodies, avoids sampling error. An additional advantage to the monoclonal assay is the ability to assay formalin-fixed, paraffin-embedded tissue. Most labs have chosen 10%–20% positive cells as the cutoff for receptor positivity, though recent studies have suggested that clients whose tumors contain as few as 1% weakly positive cells have significantly improved disease-free periods and overall survival when treated with hormonal therapy. Clients with a negative receptor status have at most an 8% chance of response to hormonal therapy.
Professional Considerations of Estradiol Receptor and Progesterone Receptor in Breast Cancer
Consent form IS required for biopsy. See Biopsy, Site-specific—Specimen for procedure-specific risks and contraindications .
- Biochemical assay or frozen-tissue immunoassay: Obtain a 60-mg solid tumor biopsy bottle (fluorescent pink), a waxed cardboard container or plastic tube without fixative, and a needle biopsy tray.
- Immunohistochemistry on paraffin block: Obtain a biopsy bottle containing 10% formalin and a biopsy tray. Use of fixatives other than 10% formalin may not yield satisfactory results.
- Local anesthetic is not used because it may destroy receptors and lead to a false-negative result.
- 0.5–1.0 mg of solid tumor tissue is removed, with care taken to remove excess fat and blood, both of which may lead to false-positive results.
- Biochemical assay or frozen-tissue immunoassay: The tissue is immediately cut into small pieces and assayed. If the assay is unable to be performed immediately, the tissue should be frozen on dry ice, in a cryostat, or in liquid nitrogen within 20 minutes of collection. The specimen will be rejected if thawed or formalin fixed. The specimen should not be placed in foil, gauze, or fixative.
- Immunohistochemistry on paraffin block: Tissue is placed in 10% formalin for not longer than 48 hours, preferably 12–24 hours. A paraffin block is then made on which an immunoassay to measure concentration of receptors may be performed.
- Apply a dry, sterile dressing to the biopsy site.
- Mild analgesics may be used for postprocedure pain.
- Depending on where the assay is performed, results may not be available for several days.
Client and Family Teaching
- A small sample of breast tissue will be removed with a hollow needle. The breast will not be numbed with an anesthetic because this can cause false-negative results, and so there will be discomfort for a short time. The procedure takes a few minutes and leaves no scar.
- Use mild analgesia for postprocedure pain if needed.
- Results may not be available for several days.
Factors That Affect Results
- Specimens not frozen within 20 minutes will falsely decrease results.
- Antiestrogen preparations taken within the last 2 months may cause a negative estradiol receptor response.
- 50%–70% of breast cancers are positive.