Background:The presence of sex steroid receptors in breast cancer tissue is of considerable diagnostic/prognostic value. However, the relative utility of the diverse assays used for receptor detection/quantitation is disputed. We compared the utility of a monoclonal antibody-based semiquantitative immunohistochemical assay of estrogen receptor alpha (irERalpha) and of quantitative single-point radioligand assays of “cytosolic” estrogen (ERc) and progesterone receptors (PRc).Material/Methods: Correlations were studied between the receptor levels in 235 breast cancers in patients treated between 1987 and 1990. Relationships were then analyzed between tumor receptor status, overall survival (OS; end-point: 10 years postmastectomy), age, axillary nodal status, and adjuvant tamoxifen in primary breast cancer patients for whom the respective data were accessible (N ≤121).Results: Univariate analysis showed no correlation between OS and the ERc status, whereas positive irERalpha status was a favorable (p

Keywords: Breast Neoplasms - drug therapy, Breast Neoplasms - metabolism, Chemotherapy, Adjuvant, Follow-Up Studies, Menopause, Receptors, Estrogen - metabolism, Receptors, Progesterone - metabolism, Survival Rate, Tamoxifen - administration & dosage, Tamoxifen - therapeutic use, Time Factors, Breast Neoplasms - metabolism, Chemotherapy, Adjuvant, Follow-Up Studies, Menopause, Receptors, Estrogen - metabolism, Receptors, Progesterone - metabolism, Survival Rate, Tamoxifen - therapeutic use, Time Factors