REPRODUCIBILITY OF SUBJECTIVE IMMUNOHISTOCHEMICAL ESTROGEN-RECEPTOR AND PROGESTERONE-RECEPTOR DETERMINATION IN HUMAN ENDOMETRIUM

To obtain a reliable scoring system for semi-quantitation of estrogen- (ER) and progesterone receptors (PgR) in human endometrial tissue, we investigated the reproducibility of subjective immunohistochemical ER and PgR determination. Specimens of frozen endometrial tissue were st ained once (n = 129) or twice (n = 22) using the ER-ICA and PgR-ICA ki ts from Abbott. The semi-quantitative approach we used included subjec tive estimates of the overall staining intensity (I) and of the fracti on of stained cells (%). Scoring was performed twice by the same obser ver and once by another observer (n = 87). Intra- and inter-observer a greement were evaluated using Kappa statistics. We found that more com prehensive scorings of I and % could not be agreed upon by the observe rs. Only simplified estimates of the fraction of cells stained and ove rall staining intensity were reproducible. Subjective estimates obtain ed by this method agreed with estimates obtained by counting (n = 38). Simplified H-scores, which were obtained by multiplication of the sim plified estimates of % and I, were reproducible, too. In addition, sem i-quantitation of ER and PgR by immunohistology was significantly corr elated to quantitation by enzyme-immunoassay (n = 39). Thus, it was po ssible to reproducibly semi-quantitate ER and PgR only by employing a very simple immunohistochemical scoring of ER and PgR.