[Immunocytochemical staining of estrogen receptor in conventional formalin-fixed paraffin sections in human breast cancer].

Immunocytochemical staining for estrogen receptor (ER) was examined in conventional formalin-fixed paraffin sections in 63 patients with breast cancer. The ER staining was performed by avidin-biotin peroxidase complex method (ABC) using monoclonal antibody against ER (H222). The ER stainability in formalin-fixed paraffin sections was compared with the levels of ER measuring dextran-coated charcoal (DCC) method, and with the stainability of ER in frozen sections. ER positive rates of paraffin sections and frozen sections were 52%, and 65% respectively. ER positive level of DCC method was seen in 62 percent of the cases. Results of ER staining in paraffin sections correlated well to those of DCC method and to those of ER staining in frozen sections. In paraffin sections as well as in frozen sections, ER staining was located at the nuclei of cancer cells. Furthermore, the variety that this method for ER can be used for retrospective studies of ER on stored blocks of breast cancer.