IMMUNOPEROXIDASE STAINING FOR ESTROGEN AND PROGESTERONE RECEPTORS IN ARCHIVAL FORMALIN-FIXED, PARAFFIN-EMBEDDED BREAST CARCINOMAS AFTER MICROWAVE ANTIGEN RETRIEVAL

Immunoperoxidase staining was performed for estrogen and progesterone receptors in 93 cases of primary breast carcinoma. Breast tumor sample s were fixed in formalin and embedded in paraffin. Antigen retrieval w as performed by microwave heating in citrate buffer, pH 6.0, using pre cisely defined and reproducible conditions. The cases studied included material from the current year and from paraffin blocks retrieved fro m archival storage dating back to 1981. In all cases, estrogen and pro gesterone receptor values determined by biochemical assay were availab le for comparison with the immunohistochemical results. We found 94% a greement of results between the two methods.