Increasing evidence suggests that E-selectin contributes to tumor growth and metastasis. E-selectin may increase tumoral angiogenesis and the adhesion of tumoral cells to endothelial cells at distant sites. The aim of this study was to assess the relationship between concentrations of circulating soluble E-selectin (sE-selectin) and clinical, pathological, and biological features in patients with breast cancer (BC). Concentrations of sE-selectin were analyzed by an ELISA method in sera from 113 patients with metastatic BC, 30 patients with primary inflammatory BC, 105 patients with primary noninflammatory BC, and 42 healthy controls. These concentrations were analyzed in terms of the clinical and pathological features of the tumors as well as in terms of the concentrations of serum inflammatory parameters (erythrocyte sedimentation rate, C reactive protein, interleukin 1 beta, and tumor necrosis factor alpha), the response to chemotherapy or hormone therapy, and the survival duration. Tumoral angiogenesis was also assessed in 68 patients with primary noninflammatory BC who had had primary surgery. The mean concentration of sE-selectin in the metastatic BC group was significantly higher than the mean concentration found in the healthy control group (33.5 versus 21.8 ng/ml; P < 0.01). In metastatic BC, the mean concentration of sE-selectin was significantly higher in patients with liver metastasis than in patients without liver metastasis (55.3 versus 26.0 ng/ml; P < 10(-5). The univariate analysis showed that high concentrations of sE-selectin were associated with reduced overall survival (P < 0.05), but this probably reflected the association between high concentrations of sE-selectin and liver metastasis. In patients with primary noninflammatory BC, a negative correlation was found between sE-selectin concentrations and the tumoral microvessel count (r = -0.47; P = 10(-4). In patients with primary inflammatory or noninflammatory BC, no correlation was found between concentrations of sE-selectin and tumor size, lymph node involvement, response to chemotherapy or hormone therapy, and survival. No correlation was found between the concentrations of sE-selectin and serum inflammatory parameters in any of the patient groups. This study suggests that in patients with metastatic BC, levels of sE-selectin are higher in the presence of liver metastasis. In patients with primary BC, high concentrations seem to be associated with reduced tumoral angiogenesis. Although several studies have previously demonstrated that the expression of cell surface E-selectin enhances the metastatic process, the shedding of sE-selectin in circulation may be considered a mechanism of inhibition of tumor progression.