Expression of CXCL12 and CXCR4 in pT3-stage gastric cancer does not correlate with peritoneal metastasis

CXCR4, a chemokine receptor, is considered to be involved in the metastastic formation of various types of cancer and could influence survival. More recently, CXCR4 was reported to be associated with peritoneal metastasis in gastric cancer, and CXCL12, its ligand, as a prognostic determinant among gastric cancer of various stages. In order to more specifically delineate the relevance of CXCR4 in peritoneal metastasis, 98 patients with pT3-stage gastric cancer who underwent gastrectomy and detection of intraabdominal free cancer cells in the peritoneal washing samples were evaluated. Immunostaining with anti-CXCL12 and anti-CXCR4 antibodies were performed for the primary tumor specimens, and correlation of the immunoreactivities with various clinicopathologic factors was evaluated. CXCR4 was detected in 61 specimens and CXCL12 in 76 specimens. No significant correlation was observed between presence of free cancer cells in the peritoneal cavity or development of clinical peritoneal carcinomatosis and expression of either the chemokine or the receptor. On the other hand, there was a trend towards correlation of expression of these molecules with recurrences to the distant lymph nodes or to the liver, although the number of events in these categories were insufficient to reach a statistical significance. In gastric cancer, CXCL12/CXCR4 axis seems to be more strongly associated with lymphatic or hematogenous metastasis than the establishment of peritoneal deposits.