A NEW IMMUNOHISTOCHEMICAL ANTIBODY FOR THE ASSESSMENT OF ESTROGEN-RECEPTOR STATUS ON ROUTINE FORMALIN-FIXED TISSUE SAMPLES

We describe a method for the immunocytochemical assessment of estrogen receptor (ER) status on routinely processed, formalin-fixed tissue us ing a recently developed commercially available monoclonal antibody (D ako 1D5) with a microwave antigen retrieval technique. A series of 90 cases of human breast carcinoma was analyzed and the staining was asse ssed using a semiquantitative microscopic scoring method and by assess ment of the percentage of nuclei showing positive staining. The result s were compared with assessment using another commercially available a ntibody (Abbott H222) and with clinical response to tamoxifen therapy. Direct comparison of the paired sets of H scores and the percentage o f positively stained nuclei using the two different techniques showed a significant correlation. By assigning an arbitrary cut-off for posit ivity of H score = 50, assessment of ER status using DAKO 1D5 antibody was found to correlate with response to tamoxifen therapy with a sens itivity of 90% and a specificity of 51%, similar to values in previous studies using other methods. We conclude that assessment of ER status using this new antibody and technique gives accurate results on routi nely processed, formalin-fixed tissue and may be used as an alternativ e to other methods. Copyright (C) 1995 by W.B. Saunders Company