Combined measurement of serum sialyl Lewis X with serum CA15-3 in breast cancer patients.

Background: Serum CA15-3 has been one of the most reliable tumor markers used in monitoring breast cancer patients; however, its sensitivity in detecting metastases is limited. To increase its sensitivity, the combined measurement of other tumor markers with CA15-3 was investigated.

Methods: Serum CA15-3, carcinoembryonic antigen (CEA) and sialyl Lewis X (CSLEX) were simultaneously measured in a prospective series of 455 postoperative breast cancer patients with or without metastasis. The diagnostic parameters sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting metastases were compared. The correlation of values between pairs of tumor markers was analyzed. The efficacy of combined measurement of two different tumor markers was also evaluated.

Results: The sensitivity for detecting metastases was 61.5, 56.9 and 52.3%; specificity was 97.2, 93.6 and 96.2%; PPV was 78.4, 59.7 and 69.4%; NPV was 93.8, 92.9 and 92.4%; and accuracy was 92.1, 88.8 and 89.9% for CA15-3, CEA and CSLEX, respectively. The values for CA15-3 were significantly correlated with those for CEA (P < 0.001) but not those for CSLEX. The combined measurement of CSLEX and CA15-3 increased the sensitivity by 17.0% but that of CEA and CA15-3 increased the sensitivity by only 10.8%. All diagnostic parameters for the combined measurement of CSLEX and CA15-3 were higher than those for the combined measurement of CEA and CA15-3.

Conclusions: These findings suggest that CSLEX may be more useful than CEA in combination with CA15-3 in monitoring breast cancer patients. The results of this study suggest that CSLEX may be more useful than CEA in combination with CA15-3 in monitoring breast cancer patients.