[Cathepsin D expression in primary breast cancer. Comparison of immunohistochemical and biochemical results]

Cathepsin D expression was immunohistochemically tested in 126 formalin-fixed and paraffin-embedded tissues from primary breast cancers. Specific staining was noted in the cytoplasm of tumor cells in 43% of tumors. In 44% of cases cathepsin D was detected in tumor stroma. A total of 63% of the tissue samples stained positive for cathepsin D (tumor and/or stromal staining). In all cases the cathepsin D level was measured in tumor cytosol by radioimmunoassay. Cytosols were considered positive when cathepsin D concentrations of over 40 pmol/mg cell protein were found. Comparison of immunohistochemical and biochemical detection of cathepsin D revealed a 76% concordance rate. Univariate analysis showed a significant correlation of cathepsin D expression with axillary node involvement; no correlation was found with tumor size, tumor grade, steroid receptor status or age of patients. Our results demonstrate a close agreement between the results of biochemical and of immunohistochemical cathepsin D detection.