Mucin-like carcinoma-associated antigen (MCA) in tissue and serum of patients with breast cancer: clinical applications in prognosis and disease monitoring.

Mucin-like Carcinoma-associated Antigen (MCA) has been associated with many breast cancers. The aim of this study was to evaluate MCA in tumor tissue and serum as a potential tumor marker for prognosis and disease monitoring. MCA levels were determined in the tissue of 196 patients with primary breast cancer, 25 with metastatic disease and 25 patients with benign diseases, in pellet and/or cytosol. MCA levels were also determined in the serum of 50 patients with benign diseases, 148 with primary breast cancer (Mo), 150 with metastatic breast cancer (MT), and 200 with no clinical evidence of disease (NED). MCA tissue concentrations in pellet and cytosol were similar: 66.7 + 251 U/mg and 41.1 + 53 U/mg, respectively. No relationship between MCA levels and tumor size or nodal involvement was found. Higher MCA levels were observed in patients with ER+ or PgR+ tumors than in those with ER- or PgR- tumors (p < 0.01). Patients with MCA pellet concentrations lower than 10 U/mg of protein had shorter disease-free intervals (DFI) than those with higher values (p < 0.05). Abnormally high serum levels of MCA were found in 8% of patients with benign diseases, 4% of NED patients, 22% of Mo patients, and in 76% of MT cases. In primary breast cancer MCA values were related to tumor size and nodal involvement. A trend toward a lower DFI in patients with elevated presurgical MCA levels was observed but was of no statistical significance. These differences became statistically significant when patients were subdivided according to nodal status, with shorter DFI in those without nodal invasion (p < 0.05). In metastatic patients, changes in serum MCA were related to the tumor's response to treatment in 82% of cases. The highest MCA values were found in patients with liver or bone metastasis and the lowest values were found in those with locoregional recurrence. In conclusion, although MCA is not a specific tumor marker, it can be useful as a prognostic factor (tissue and serum) and in monitoring metastatic patients.