Immunohistochemical image analysis of estrogen and progesterone receptors in breast cancer

Background: Recently objective quantification of immunohistochemical estrogen receptor (ER) and progesterone receptor (PgR) staining in breast cancer by image cytometry has been predominantly performed by measuring the area of positively stained cells. However, in sample preparations of immunostained hormone receptors, both the stained area and the intensity of staining vary. In this study, we performed quantification of the stained area by measuring, tailing intensity using image cytometry. Methods: Quantitative analysis of ER and PgR immunohistochemistry was performed using image cytometry. The obtained values were presented as % of positive staining (%PS). Comparison of %PS with values obtained by EIA and with clinicopathological features was performed. Results: The %PS values and the natural logarithm of the EIA levels of the hormone receptors showed a significant positive correlation for both ER and PgR. The concordance of the results obtained by the two methods was 96.3% for ER and 73.7% for PgR. The ER-%PS values of postmenopausal patients were significantly higher than those of premenopausal patients, whereas the PgR-%PS values of the former group were significantly lower than those of the latter group. Conclusions: The quantification of ER and PgR in immunostained preparations using %PS as a parameter was reproducible and showed a high correlation with values obtained by EIA. It was shown that only menopausal status affects hormone receptor levels when analyzing the relationship between %PS measurements and clinicopathological features.