Elevated serum levels of sialyl Lewis X (sLe X ) and inflammatory mediators in patients with breast cancer.

Purpose: The carbohydrate sialyl Lewis ^X (sLe ^X ) mediates cell adhesion, is critical in the normal function of immune cells, and is frequently over-expressed on cancer cells. We assessed the association, differential levels, and prognostic value of sLe ^X and inflammatory cytokines/chemokines in breast cancer sera.
Methods: We retrospectively measured sLe ^X and a panel of cytokines/chemokines in the sera of 26 non-invasive ductal carcinoma in situ (DCIS), 154 invasive non-metastatic breast cancer (non-MBC), 63 metastatic breast cancer (MBC) patients, and 43 healthy controls. Differences in sLe ^X and inflammatory cytokines among and between patient groups and healthy controls were assessed with nonparametric tests and we performed survival analysis for the prognostic potential of sLe ^X using a cut-off of 8 U/mL as previously defined.
Results: Median serum sLe ^X was significantly higher than controls for invasive breast cancer patients (MBC and non-MBC) but not DCIS. In univariate analysis, we confirmed patients with serum sLe ^X  > 8 U/mL have a significantly shorter progression-free survival (PFS) (P = 0.0074) and overall survival (OS (P = 0.0003). Similarly, patients with high serum MCP-1 and IP-10 had shorter OS (P = 0.001 and P < 0.001, respectively) and PFS (P = 0.010 and P < 0.001, respectively). sLe ^X , MCP-1 and IP-10 remained significant in multivariate survival analysis.
Conclusion: Elevated serum sLe ^X was associated with invasive cancer but not DCIS. High serum sLe ^X levels were associated with inflammatory mediators and may play a role in facilitating local invasion of breast tumor. Furthermore, serum MCP-1, IP-10 and sLe ^X may have prognostic value in breast cancer.