ABSTRACT
To evaluate the reliability of immunohistochemical estrogen receptor (ER) in the prognosis of patients with breast cancer, 83 primary tumors from patients were studied. Immunohistochemical analysis (IHA) was performed using antibody ER 1D5 (Dako) together with microwave treatment for antigen retrieval. ER values obtained using the biochemical steroid binding assay (polyethyleneglycol method, PEG) were available for comparison. Of all tumors, ER positivity was detected in 44.6% by IHA and 36.1% by PEG method. The concordance between the two methods was 69%. No significant correlation was found between the ER status determined by both methods and clinical stage, tumor size, lymph node status or age of patient at diagnosis. However, we found that the immunohistochemical ER is a superior predictor of early recurrence in patients with primary breast cancer to biochemical ER. The findings in the present study emphasize the clinical benefit of the immunohistochemical ER assay as a measure for prognosis.