Abstract
Tumor-infiltrating immune cells are associated with tumor prognosis, although the type of immune cells responsible for local immune escape is still unknown. This study examined the relationship between gastric cancer survival and the density of immune cells, including CD8(+) T cells, CD20(+) B cells, and CD33(+)/p-STAT1(+) cells, which represent myeloid-derived suppressor cells, to evaluate the role of immune cells in the progression of gastric cancer. One hundred pathologically confirmed specimens were obtained from stage IIIa gastric cancers between 2003 and 2006 at Sun Yat-sen University Cancer Center, China. The density of tumor-infiltrating immune cells in tumor tissue was examined using immunohistochemical analysis. Clinicopathologic parameters and the survival rate were analyzed in relation to the density of immune cells. A high density of CD8(+) T cells and CD20(+) B cells was associated with a good clinical outcome, but a high density of CD33(+)/p-STAT1(+) cells was associated with a poor clinical outcome. Most importantly, the density of CD33(+)/p-STAT1(+) cells was an independent prognostic factor and inversely related to the infiltration of CD8(+) T cells. Although the infiltration of CD8(+) T cells and CD20(+) B cells is involved in the progression of gastric cancer, these data suggest that CD33(+)/p-STAT1(+) cells play a central role in the regulation of the local immune response, suggesting that CD33(+)/p-STAT1(+) cells might be therapeutic targets in gastric cancer.