PROGESTERONE RECEPTORS IN ROUTINELY PARAFFIN-EMBEDDED PRIMARY BREAST CARCINOMAS AND LYMPH-NODE METASTASES

Described here is an immunohistochemical technique using the commercia lly available monoclonal progesterone receptor (PR) antibody KD 68 in routinely fixed and paraffin-embedded breast carcinomas and lymph node metastases. The authors' technique is compared with several incubatio n variations. The method applying the primary antibody in a dilution o f 1:10 overnight followed by a biotinylated second antibody showed the best results when Triton X-100 was added to the buffer. Using this me thod, comparison with the results on frozen sections of 34 breast carc inoms yielded a significant concordance of 94%. Correlation between th e results on paraffin sections and those obtained by the standard dext ran-coated charcoal cytosol assay was 80%. The value of the method for predicting endocrine therapy response was shown in 20 patients. Thus the reliability of the method has been demonstrated and was applied on 151 lymph node metastases and the corresponding primary breast carcin omas from 50 patients. Generally PR content in the metastases was lowe r than in the primary tumors (p < 0.001). This finding indicates that evaluation of PR in lymph node metastases should be included in the de cision for endocrine therapy of breast cancer.