COMPARISON OF A NOVEL ASSAY FOR BREAST-CANCER MUCIN TO CA15-3 AND CARCINOEMBRYONIC ANTIGEN

Purpose: To compare the sensitivity and specificity of an automated microparticle enzyme immunoassay (MEIA) for breast cancer mucin (IMx BCM; Abbott Laboratories, North Chicago, IL) to that of CA15-3 and carcinoembryonic antigen (CEA) for detecting and monitoring breast cancer. Materials and Methods: IMxBCM was compared to assays of CA15-3 and CEA in 630 serum specimens from healthy women, and from women with breast cancer, other malignancies, benign breast conditions, or other benign diseases. Results: Analysis of the log-transforms for the three markers in all specimens showed a high correlation of IMxBCM with CA15-3 (r = .78), but not with CEA (r = .25). Based on a receiver-operating-characteristics (ROC)-curve analysis for any given specificity, IMxBCM was found to be a more sensitive marker than either CA15-3 or CEA for distinguishing 105 women with advanced or metastatic breast cancer from 89 healthy women (P = .003 and P = .04, respectively), from 98 women with benign breast conditions (P = .02 and P = .002), or from 191 women with benign diseases (P = .03 and P < .0001). At 95% specificity, the sensitivities of IMxBCM, CA15-3, and CEA for detecting advanced or metastatic breast cancer were 69%, 51%, and 30%, respectively. Serial serum samples (n = 177) were analyzed in 20 additional metastatic breast cancer patients with measurable disease. Serial IMxBCM levels corresponded with the clinical course of disease in 80%, CA15-3 in 65%, and CEA in 60% of the 20 patients. Conclusions: Increased sensitivity of IMxBCM, despite a high correlation with CA15-3, suggests that IMxBCM and CA15-3 may recognize distinct epitopes on the same molecule. Although further research is indicated, IMxBCM may provide a promising marker in the clinical management of breast cancer patients. © 1992 by American Society of Clinical Oncology.