A preliminary report on the usefulness of monoclonal antibodies to CA 15-3 and MCA in the detection of micrometastases in axillary lymph nodes draining primary breast carcinoma.

The most critical factor affecting survival in patients with breast carcinoma is axillary nodal involvement. Monoclonal antibodies raised against specific human mammary tumour associated antigens may increase detection of micrometastases. This preliminary report examines two of these antigens; CA15-3 antigen and mucin-like carcinoma associated antigen (MCA) in the detection of such deposits. Specimens from 39 stage 1 (node negative) breast carcinoma patients were assessed. Two further 'negative' sections were stained with antisera to CA15-3 and MCA antigens. Micrometastases were detected in 5 patients and in each, MCA and CA15-3 identified the same micrometastases. 3 of these patients had disease progression compared with 3/34 of the remaining patients. The use of monoclonal antibodies to CA15-3 and MCA significantly (P less than 0.05) increases detection rates of micrometastases and this is associated with significantly worse disease-free survival rates (P less than 0.001).