COMPARISON OF CATHEPSIN-D DETERMINATIONS IN HUMAN CARCINOMAS BY ENZYME-IMMUNOASSAY AND IMMUNORADIOMETRIC ASSAY

Overexpression of cathepsin D in several types of carcinoma in women a ppears to be associated with a poor clinical course. In this prospecti ve investigation, cathepsin D levels in 170 specimens of normal and ne oplastic human tissues were determined simultaneously by enzyme immuno assay (EIA) and immunoradiometric assay (IRMA) to allow comparisons in multicentric studies, such as cooperative clinical trials. Nonmaligna nt uteri and specially prepared reference powders were also evaluated. Linear regression analysis between the two assays for all specimens [ EIA = 0.87(IRMA) - 3.18] demonstrated a correlation coefficient (r) of 0.99 (P < 0.001). When malignancies were categorized by the tissue or igin (i.e., breast, uterus, ovary, lymph node, and colon), highly sign ificant correlations were also observed (regressions slopes ranged fro m 0.58 to 1.02). Intra- and interassay controls conducted for the new EIA procedure gave CV% ranging from 4.4 to 10.2, which was similar to the IRMA test for cathepsin D. The results of both assays correlated w ell and were highly reproducible. Either assay may be used with confid ence that comparable cathepsin D values will be obtained in a wide ran ge of tissue biopsies. (C) 1995 Wiley-Liss, Inc.