estrogen receptor assay
estrogen receptor assayOncology The ER is a protein found in high concentrations in the cytoplasm of breast, uterus, hypothalamus, and anterior hypophysis cells; ER levels are measured to determine a breast CA's potential for response to hormonal manipulation–60% of breast CAs are 'estrogen positive';1⁄2 of ER-positive Pts respond favorably to anti-estrogen–tamoxifen citrate therapy, in contrast to <1⁄3 of ER-negative Pts. See 'Flare' phenomenon. Cf Progesterone receptor assay.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.