Comparative histochemical and biochemical assays of estrogen receptors in breast cancer patients.

Estrogen receptors (ER) in breast cancer tissue were determined in 51 patients by a histochemical method with estradiol-17 beta-bovine serum albumin-fluorescein isothiocyanate conjugate and were compared with those in the adjacent tissue determined by biochemical method, i.e., the sucrose density gradient (SDG) and dextran-coated charcoal (DCC) methods. Excluding one non-evaluable case, 26 specimens were ER(+) and 24 were ER(-) in histochemical assay. The presence of ER(+) cells in histochemical assay was not related to menopause or to the molecular pattern of ER determined by the ASG method, or to the histological type of cancer. The percentage of fluorescent cells to all cancer cells was not related to the number of binding sites of ER determined by the DCC method. As determined by the histochemical assay, breast cancer cells having ER accounted for 20 to 100% of all cancer cells examined and ER(+) cells were in clumps or intermixed with ER(-) cells in cancer tissue. The co-existence of Er(+) and Er(-) cells may be one reason for the fact that surgical ablation of breast cancer rarely results in complete tumor regression.