Use of mucin like cancer associated antigen (MCA) in the management of breast cancer.

A study of the epithelial mucin marker MCA was made in 233 patients with breast cancer. Only 6% of 72 patients with Stage I-III disease had a raised MCA (greater than 15 U ml-1) when assessed following surgical treatment of the primary tumour. Raised levels of MCA occurred in one out of 20 (10%) patients with stable local recurrence, and six out of ten (60%) patients with progressive local recurrence. In 115 patients with metastases 89 (77%) had a raised MCA, tumour extent and disease activity both influenced the MCA level. The change of MCA level during the treatment of 11 cases of local recurrence and 55 cases of metastatic disease showed a 64 and 84% concordance respectively with the change in clinical status. Coincidental measurement of MCA and bone scans showed a raised MCA in one out of 63 (1.5%) patients with negative or equivocal scans, and 26 out of 35 (74%) with positive scans. MCA provides a useful marker for the monitoring of the treatment of local recurrence and metastatic disease, and an independent indicator of the effects of changes in treatment.