Comparison of tumour markers TAG 12 with CA 15-3 and MCA in breast cancer diagnosis.

The aim of the present study was to evaluate the clinical value of the new tumour marker TAG 12 in sera from patients with breast cancer (n = 123), patients with benign breast disease (n = 30) and normal controls (n = 38). The results for TAG 12 were compared with those for CA 15-3 and MCA. The cut-off levels (90% specificity) determined for each test in the benign and control groups were 57.5 kU/1 for TAG 12, 24.8 kU/1 for CA 15-3 and 11.8 kU/1 for MCA. The diagnostic sensitivity of the TAG 12 test was 0.30, 0.19 for CA 15-3 test and 0.20 for MCA test in detecting breast cancer. TAG 12, CA 15-3 and MCA tests were tested in a multivariate analysis to find the best combination of independent predictors of breast cancer. The most important predictor of breast cancer was TAG 12. In order to evaluate the contributions of different tumour marker serum tests a stepwise discriminant analysis was carried out. The discriminant function is DF = TAG 12 x 0.0349 + CA 15-3 x 0.0568 + MCA x (-0.33) - 0.53. The sensitivity of the DF in detecting breast cancer was 31% with a specificity of 91% and a efficiency of 52%. The correlation coefficient in breast cancer patients between TAG 12 and CA15-3 measurements was 0.95, and 0.90 between TAG 12 and MCA measurements. In conclusion, the results indicate that TAG 12, CA 15-3 and MCA have only limited value in the diagnosis of breast cancer, but their role in monitoring and follow up of breast cancer patients is a subject for further investigation.