A new tumor marker MCA in breast cancer diagnosis.

The serum concentration of the new tumor marker MCA (mucinous carcinoma associated antigen) was determined by an enzyme immunoassay kit method, which is based on the use of a monoclonal antibody b12. The mean MCA values in breast cancer patients (n = 40) were significantly higher than in patients with benign breast disease (n = 55, p less than 0.001) and in control subjects (n = 37, p less than 0.001). When we used the cut-off level 11 KU/l for MCA, 6/37 (16.2%) of control subjects 7/55 (12.7%) of patients with benign breast disease, 18/40 (45.0%) of all breast cancer patients 11/19 (57.9%) of breast cancer patients with axillary node involvement, and 1/1 breast cancer patient with distant metastases were above this cut-off level. For comparison, at the cut-off level of 5 micrograms/l the CEA test was positive in 7/40 (18%) cancer cases, and in 6/19 (32%) of cancer patients with nodal involvement. Patients with axillary nodal metastasis showed higher values than patients without metastasis in both tests (p less than 0.01). The combination of MCA at 11 KU/l cut-off level and CEA at the 5.0 micrograms/l cut-off level reached the diagnostic sensitivity of 0.53, efficiency of 0.73, and specificity of 0.87. It seems that MCA is a promising tumor marker in breast cancer. Especially high values may have diagnostic significance.