The usefulness of CA15.3, mucin-like carcinoma-associated antigen and carcinoembryonic antigen in determining the clinical course in patients with metastatic breast cancer.

Levels of mucin-like carcinoma-associated antigen (MCA), CA15.3 and carcinoembryonic antigen (CEA) were measured in consecutive serum samples of 40 women with metastatic breast cancer. A change in antigen level of more than 25%, either an increase or a decrease, was considered to predict progressive or responsive disease respectively. A change of less than 25% was considered to predict stable disease. MCA, CA15.3 and CEA were elevated in the serum of 68%, 76% and 48% of the patients respectively (P < 0.05). The overall prediction of clinical course was similar for all three markers. A more than 25% increase of MCA, CA15.3, and CEA was observed in 61%, 54% and 36% respectively. The predictive value of a more than 25% increase was high for all three markers: 94%, 94%, 83%. Changes in marker levels were correlated with each other. Logistic regression analysis showed that combining MCA and CA15.3 did not improve the prediction further. In conclusion, these tumour markers may help in evaluating the disease course and there is no advantage in combining MCA and CA15.3.