A simplified histoscore for the estrogen receptor assay in breast cancer.

Different histoscores combining the number of positive cells and the intensity of staining have been used to evaluate the estrogen receptor immunocytochemical assay (ER-ICA). Our aim was to investigate if the simple estimation of the amount of positive cells could be sufficient for the semiquantitative analysis of ER-ICA. Tissue from 51 women with ductal breast carcinoma was used. Half of each sample was processed with the quantitative assay (ER-EIA) and the other half with ER-ICA. Microscopical analysis was performed by two independent observers and classified on a simple scale from 0 to 4+. With EIA 31 cases (60.78%) were positive and 20 (39.21%) negative. With ER-ICA 29 (56.86%) had immunostaining, whereas 22 (43.13%) did not. 95.83% of the ER-ICA positive cases and 77.7% of ER-ICA negative had a good correlation with EIA values. Statistical analysis showed a high degree of correlation (r = 0.88 p 0.001). Hence, simple semiquantitative estimation in ER-ICA is sufficient to provide useful information for clinical use about ER content in tissue sections.