Estrogen Progesterone Receptors Immunohistochemistry Biopsy Tissue

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. 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. Estrogen receptors (ER) and progesterone receptors (PR; also called PgR) may be found in breast cancer cells. Cancer cells with these receptors depend on estrogen and related hormones, such as progesterone, to grow. Estrogen and progesterone influence many hormonal functions in women, such as breast development. If breast cancer cells have estrogen receptors, the cancer is called ER-positive breast cancer. If breast cancer cells have progesterone receptors, the cancer is called PR-positive breast cancer. If the cells do not have either of these two receptors, the cancer is called ER/PR-negative. About two-thirds of breast cancers are ER and/or PR positive.