INDIVIDUAL REFERENCE RANGES OF CA-15-3, MCA AND CEA IN RECURRENCE OF BREAST-CANCER

The long-term intra-individual variation of the title tumour markers w as studied in the group of 33 patients which developed no relapse. The average biological intra-individual CV was 11.2% for CA 15-3 and 14.9 % for MCA whereas those of CEA strongly depended on the concentration. The intra-individual standard deviation of CEA was independent of con centration and amounted to 0.23 g/L. Individual reference ranges the a nalytes were much smaller than the group reference ranges. Individual reference Limits were calculated on the basis of the average intra-ind ividual variation. In 21 of the 22 patients who developed recurrence d uring the follow-up period, individual reference limits of CA 15-3 and /or CEA were exceeded 1 to 31 months (median 10 months) before clinica l evidence (diagnostic sensitivity 95%). Group reference limits were e xceeded only in 13 patients (diagnostic sensitivity 60%) and occurring later. The diagnostic specificity was 97%. MCA did not provide additi onal information. The combination of CA 15-3 and CEA is an excellent f or detection and exclusion of recurrence in the follow-up of breast ca ncer patients if decisionmaking is based on individual reference limit s. Improvement of the long-term analytical quality of the tumour marke r assays, particularly in the low concentration range is necessary.