Cancer-associated antigen CA 15-3 in the diagnostics of breast tumours.

The serum concentration of the new marker CA 15-3 was determined by a kit method, which is based on the use of two different monoclonal antibodies 115D8 and DF3, in a coated tube immunoradiometric technique. The mean CA 15-3 values in breast cancer patients (n = 40) were significantly higher than in patients with benign breast disease (n = 52, p less than 0.001) and in control subjects (n = 32, p less than 0.001). When we used the cut-off level 35 kU/l for CA 15-3, 0/32 of control subjects, 1/52 (2%) of patients with benign breast disease, 8/40 (20%) of all breast cancer patients, 6/19 (32%) of breast cancer patients with axillary nodal involvement and 1/1 of breast cancer patients with distant metastases were above this level. Among the same patients the CEA serum test was positive at a cut-off level of 5 micrograms/l in 7/40 (18%) cancer cases, and in 6/19 (32%) of cancer patients with nodal involvement. When we used the cut-off level 35 kU/l for CA 15-3 and 5 micrograms/l for CEA 1/52 (2%) of patients with benign breast disease, 10/40 (25%) of all breast cancer patients, 7/19 (37%) patients with axillary nodal involvement and 1/1 of breast cancer patients with distant metastases were positive in one or both of the tests. The serum CA 15-3 and CEA values were higher in patients with tumour size above 2 cm in diameter than in patients with smaller tumours (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)