Estrogen Receptor/Progesterone Receptor (ER/PR), Immunohistochemical, Paraffin Block

Formalin-fixed, paraffin-embedded (FFPE) tumor

One paraffin block or seven unstained, positively-charged tissue slides cut at 4 to 5 microns and dried for one hour at 60°C

Paraffin block transport pouch or slide mailer

Cancer prognosis: ER and PR positivity is a favorable prognostic factor in breast and endometrial carcinoma and meningioma.

Response to endocrine therapy: Combined ER and PR positivity is associated with increased response to antiestrogen therapies.

In the absence of internal positive control staining, a false-negative result cannot be excluded. The presence or absence of positive internal control staining is indicated on all negative reports. Use of fixatives other than 10% formalin may not yield equivalent or satisfactory results.

Immunohistochemistry (IHC). This is a semiquantitative measurement of ER/PR positive tumor nuclei in stained histologic tissue sections.

Estrogen receptors (ER) are cellular proteins that bind estrogens with a high affinity and specificity. They are a necessary component for estrogen-mediated cellular activity. The presence of progesterone receptors (PR) demonstrates an active ER mechanism for the induction of PR expression. Immunohistochemical staining permits the detection and localization of ER/PR within sections from formalin-fixed, paraffin-embedded tissue.

Clinical utilities for the measurement of ER/PR include patient prognosis and patient response to adjuvant endocrine therapy. Individuals with receptor-positive tumors generally have a better prognosis, as indicated by a longer interval to disease recurrence and a longer overall survival, than patients with receptor-negative tumors. Studies have also shown that the determination of receptor status by immunohistochemistry may be useful in predicting patient response to hormonal therapy.