Quantification of MUC1 in breast cancer patients

Objective : To compare the performance of four serum assays for the quantification of MUC1 in breast cancer patients. Study design : A total of 282 serum samples were evaluated with two automated (Boehringer Mannheim Enzymun-Test® CA 15-3 and Chiron ACS™ BR) and two manual assays (Centocor CA 15-3® radioimmunoassay [RIA] and Biomira Truquant® BR RIA™). Sera were obtained from healthy controls ( n =50), patients with benign ( n =25) and malignant breast disease ( n =77) and patients with other malignancies ( n =69). In addition, sera from pregnant women ( n =56) and patients with liver cirrhosis ( n =5) were included. Results : Intraassay coefficients of variation (C.V.s) were highest for the manual Centocor CA 15-3 assay (7.4% for values below 50 kU/l and 8.1% for values above 180 kU/l). Interassay C.V.s were highest for the manual Truquant BR assay (11.7% for the lower concentration values and 18.6% for the higher concentration values). False positive rates ranged between 0% for the Centocor CA 15-3 RIA and 14% for the ACS BR assay (cut-off: 30 kU/l). In monitoring breast cancer patients all four assays show similar patterns, although absolute MUC1 values found may differ up to 50%. Conclusion : For monitoring purposes all assays perform equally well, however, automated assays show lower inter- and intraassay variability, especially in the higher value range. Therefore we recommend the use of the same, automated, assay for quantification of MUC1 during the follow-up of breast cancer patients.