A cytoplasmatic estrogen receptor related protein (ER-D5 Ag) in breast cancer.

A monoclonal antibody against an Estrogen Receptor Related Protein (EG-D5 AG by Amersham) was analyzed in evaluating hormone dependence in 188 breast cancers, in addition to current index of steroid receptors. The Authors observed that the concentration of this new Antigen is not related with PgR but with ER concentration. In fact, increasing the ER values, increases the concentration of ER-D5 Ag, showing a good correlation between these two tumoral markers. In regard to Progesterone Receptor ranges, the ER-D5+ves were equally distributed between PgR-ves and PgR+ves Our experience suggests the application of ER-D5 Ag as R-ves tumor screening marker and emphasizes the importance of a second level in determining therapy and prognosis in breast cancer.