Lack of correlation between serum levels of E- and P-cadherin fragments and the presence of breast cancer.

Breast cancers often show reduced expression of the transmembrane cell-cell adhesion protein, E-cadherin. In addition, approximately half of breast carcinomas express P-cadherin, which correlates with poor survival. A large fragment of the E-cadherin extracellular domain can be detected in serum, and it has been proposed that an increase in serum E-cadherin can denote the presence of a tumor. In this study, we tested the possibility that serum E- or P-cadherin levels might be useful diagnostic or prognostic indicators in breast cancer. However, we found no indication that the level of serum E-cadherin correlated with the presence of breast cancer. In addition, although we successfully detected a fragment of P-cadherin in serum, we found that its level was considerably lower than that of E-cadherin and did not correlate with the presence of P-cadherin-positive breast cancer.