Multicenter technical and clinical evaluation of a fully automated enzyme immunoassay for CA 125

The technical performance and clinical usefulness of the newly developed Enzymun-Test CA 125 (Boehringer Mannheim) was evaluated in a multicenter study. Sera tested were obtained from healthy control subjects (n = 1003) and from patients with benign conditions (379), ovarian cancer (518), or other malignancies (479). Intra- and interassay variability was low at CA 125 concentrations greater than 100 units/mL. Intra- and interassay CVs were respectively less than or equal to 36% and 23% for the low CA 125 concentrations (less than or equal to 35 units/mL) and less than or equal to 15% and 14% for the medium CA 125 concentrations (36- less than or equal to 100 units/mL). Interlaboratory reproducibility of the Enzymun-Test CA 125 was excellent. A strong linear correlation was observed between Enzymun-Test CA 125 and three of four other commercially available assays of CA 125 in serum. Cutoff values of 35 units/mL in three of these other tests corresponded to Enzymun-Test CA 125 values ranging from 27.0 to 42.1 units/mL. In the fourth test, an enzyme immunoassay, a cutoff of 35 units/mL corresponded to Enzymun-Test values ranging from 64.1 to 77.0 units/mL. Discordant, as yet unexplained, results in which Enzymun-Test values were greater than 65 units/mL and Centocor CA 125 immunoradiometric assay results were less than 35 units/mL were found in 15 of 1003 samples (1.5%) of apparently healthy control subjects. Sensitivity and performance of the Enzymun-Test were very similar to those of the Centocor assay for sera from the patients with various benign disorders or malignant diseases. Given its excellent automated technical performance, this new CA 125 serum assay is feasible for monitoring ovarian cancer patients. Test results are interchangeable with those from other laboratories and, in general, with those obtained by most other CA 125 tests.