Semiquantitative estimation of steroid hormone receptors by immunohistochemistry applied to paraffin sections is common practice in surgical pathology Flow cytometric (FCM) analysis of estrogen receptor (ER) and progesterone receptor (PR) levels provides a faster and more objective quantitative assay. However, a major problem in such FCM analyses of solid tumor samples is the admixture of tumor cells with normal epithelial, stromal, and inflammatory cells. The aim of the underlying study was to investigate the applicability of a recently developed multiparameter flow cytometric methodology for the accurate estimation of the fraction of steroid hormone receptor-positive tumor cells and to explore whether this multiparameter approach allows the detection of specific, clinically relevant subsets of tumors, based on a combination of ploidy level, steroid hormone receptor status, and cell cycle characteristics. For this purpose, samples of 42 breast cancer patients, from which routine immunohis tochemistry for ER and PR also was available, were analyzed. From each case, a cell suspension was prepared from the paraffin block by applying a heating and short pepsin digestion step to 50-mu m-thick sections. These cell suspensions were double-immunostained for cytokeratin to identify the epithelial cells, and ER or PR, whereas DNA was quantitatively stained with propidium iodide using an optimized protocol. In the entire group of breast tumors, the percentages of ER- and PR-positive cells were registrated in the epithelial subfraction, in combination with DNA ploidy and S phase fraction (SPF). A significant correlation was found between the fraction of hormone receptor-positive cells as found by the immunohistochemical and FCM procedures. For ER, a correlation coefficient of r = .87 was found, and for PR r = .62, both P Company.
Leers, M. P. G., Schutte, B., Theunissen, P. H. M. H., Ramaekers, F. C. S., & Nap, M. (2000). A novel flow cytometric steorid hormone receptor assay for paraffin embedded breast carcinomas : An objective quantification of the steroid hormone receptors and direct correlation to ploidy status and proliferative capacity in a single-tube assay. Human Pathology, 31, 584-592. https://doi.org/10.1053/hp.2000.6700