Mucin-like carcinoma associated antigen (MCA) at presentation with breast cancer.

The usefulness of serum measurements of mucin-like carcinoma associated antigen (MCA) in 100 women at presentation with breast cancer was evaluated. Peripheral venous blood was drawn and MCA values determined by radioimmunoassay. Twenty women presenting with benign breast disease and 20 normal women served as controls. There was no difference in the MCA values between the benign breast disease group and the normal group: 4.1 +/- 0.9 units/ml versus 5.0 +/- 0.75 units/ml (mean +/- sem). The following were the MCA values for patients by stage; stage 1: 11.2 +/- 1.02, stage 2: 11.0 +/- 1.29, stage 3: 20.2 +/- 6.7, stage 4: 31 +/- 5.0. Statistical analysis of stage versus controls showed significant elevations only in stage 3 and 4 disease (p < 0.05). We conclude that MCA may be a useful serum tumour marker only in advanced breast cancer but is unreliable in detection of early breast cancer.