[Mucin-like carcinoma-associated antigen: sensitivity and specificity in metastatic breast cancer].

The clinical usefulness of a tumor marker essentially depends on its sensitivity and specificity for a certain tumor. To prove, wheather the new tumor marker 'mucin-like carcinoma-associated antigen' could be used for the management of breast cancer patients, we determined its serum concentration in 50 healthy blood donors, 130 patients with various non-malignant diseases, 138 patients with different metastazised tumors and 137 breast cancer patients. 78 of the breast cancer patients had known metastases while 59 had no evidence of disease after initial surgical and adjuvant therapy. Only 2% of the blood donors and 3% of the patients with non-malignant diseases exceeded the cut-off level of 15 U/ml. In contrast to these findings, 28% of patients with various metastazised tumors and 77% of patients with metastazised breast cancer had serum levels above 15 U/ml. Breast cancer patients without evidence of disease had elevated marker values in only 3%. In breast cancer the serum levels of this antigen depends on the type of metastases. Maximal concentrations were found in mixed metastases while cutaneous or lymph-node metastases showed the lowest rate of positivity. Furthermore a good correlation of serial determined marker levels with the course of the disease was observed, so that we conclude, that mucin-like carcinoma-associated antigen can be used in follow-up of patients with metastazised breast cancer. Because of its high sensitivity and specificity it provides some advantage over other markers used in this disease.