Simple method for comparing reliability of two serum tumour markers in breast carcinoma.

Aims-To compare the two breast tumour markers, CA15-3 and mucinous-like carcinoma associated antigen (MCA), using Receiver Operating Characteristic (ROC) curve analysis. Methods-One hundred and ninety six patients ''presenting'' with breast carcinoma had serum CA15-3 and MCA concentrations measured. Results-Using these markers as indicators of stage IV disease at the recommended laboratory level, true positive rates (TPR) and false positive rates (FPR) were obtained as follows: CA15-3 TPR = 75%, FPR = 7.4%, MCA TPR = 80%, FPR= 59.1%. By increasing the CA15-3 cutoff level to 45 U/ml, a TPR and FPR of 75% and 0.6%, respectively were obtained. By increasing the MCA cutoff level to 23 U/ml, a TPR and FPR of 65% and 2.3%, respectively, were obtained. Conclusions-Using ROC curve analysis shows that CA15-3 is a superior indicator of metastatic breast disease than MCA at recommended laboratory levels, and by altering the cutoff points, the specificity and sensitivity for both these markers can be improved.