Comparison of breast cancer mucin (BCM) and CA 15-3 in human breast cancer.

The Breast Cancer Mucin (BCM) enzyme immunoassay utilizes two monoclonal antibodies (Mab), M85/34 and F36/22, for the identification of a mucin-like glycoprotein in serum of breast cancer patients. We have compared BCM with CA 15-3, another member of the human mammary epithelial antigen family. Serum BCM was evaluated in 151 and CA 15-3 in 134 patients with breast cancer, in 30 normal controls, in 9 pregnant women, and in 13 cancer patients (non-breast). Neither the normal controls nor the pregnant women had BCM levels greater than 25 U/ml. In contrast, 87 of 115 patients (75%) with metastatic breast cancer had BCM levels greater than 25 U/ml. All control persons had CA 15-3 levels less than 25 U/ml, but 2 out of 9 pregnant women (22%) had levels greater than 25 U/ml. Seventy-four out of 97 patients (76%) with metastatic breast cancer had CA 15-3 levels greater than 25 U/ml. A statistically significant correlation was found between BCM and CA 15-3 in the breast cancer patient group (r = 0.883, p less than 0.001, n = 134) and in the normal control group (r = 0.743, p less than 0.001, n = 30). BCM and CA 15.3 both showed no correlation with CEA in breast cancer patients (r = 0.060, n = 81; and r = 0.146, n = 78, respectively). BCM had a range of sensitivity similar to that of the CA 15-3 RIA. Our results suggest that BCM may be a useful new marker for monitoring the clinical course of patients with breast cancer.(ABSTRACT TRUNCATED AT 250 WORDS)