Total and lipid-bound serum sialic acid in benign and malignant breast disease.

Elevation in the total sialic acid (TSA), TSA/total protein (TSA/TP) and lipid-bound sialic acid (LASA) concentration in serum occurs in breast cancer and we have studied the applicability of the assays in classification of undefined breast tumors. Sialic acid was determined by HPLC and the statistical evaluation included the receiver operating characteristic (ROC) and Youden's index analyses. In cancer patients, the serum LASA and TSA concentration was significantly higher (p < 0.05) than in patients with benign breast disease and all the markers were significantly higher (p < 0.0001) than in normal controls. All the markers had a low accuracy (AUCs < 0.75) in differentiating between breast cancer and benign breast disease and at the specificity level of 0.95 the corresponding sensitivities were 0.32 (TSA), 0.14 (TSA/TP) and 0.23 (LASA). The results indicate that both breast cancer and benign breast disease cause elevation of TSA, TSA/TP and LASA values in serum and do not provide reliable classification of undefined breast tumors.