Tumor associated macrophages are major inflammatory cells that play an important role in the tumor microenvironment. In this study, we investigated the prognostic significance of tumor associated macrophages (TAMs) in MSI-high gastric cancers using immunohistochemistry. CD68 and CD163 were used as markers for total infiltrating macrophages and M2-polarized macrophages, respectively. The density of CD68+ or CD163+ TAMs in four different areas (epithelial and stromal compartments of both the tumor center and invasive front) were analyzed in 143 cases of MSI-high advanced gastric cancers using a computerized image analysis system. Gastric cancers were scored as “0” or “1” in each area when the density of CD68+ and CD163+ TAMs was below or above the median value. Low density of CD68+ or CD163+ macrophages in four combined areas was closely associated with more frequent low-grade histology and the intestinal type tumor of the Lauren classification. In survival analysis, the low density of CD163+ TAMs was significantly associated with poor disease-free survival. In multivariate survival analysis, CD163+ TAMs in four combined areas, stromal and epithelial compartments of both tumor center and invasive front were independent prognostic indicator in MSI-high gastric cancers. In addition, the density of CD163+ TAMs correlated with tumor infiltrating lymphocytes (TILs). Our results indicate that the high density of CD163+ TAMs is an independent prognostic marker heralding prolonged disease-free survival and that the prognostic implication of CD163+ TAMs might be determined by the proportional balance of TAMs and TILs in MSI-high gastric cancers.

It has been recently suggested that the expression levels of mutant HSP110 could be a prognostic marker in colorectal cancer with a high level of microsatellite instability (MSI-H). The aim of our study was to validate the prognostic significance of HSP110 mutation using immunohistochemistry and DNA testing in MSI-H colorectal cancer. Wild-type HSP110 (HSP110wt)-specific immunohistochemistry was performed in 168 MSI-H colorectal cancer tissues, and their expression levels were evaluated using a four-tier scoring system (0/1 þ /2 þ /3 þ ). Of these tissues, 167 cases were analyzed for HSP110 T 17 deletion. Associations with clinicopathological, molecular and survival parameters were statistically analyzed. The low-level expression of HSP110wt (0/1 þ ) was observed in 40 MSI-H colorectal cancers (24%) and was significantly related to large HSP110 T 17 deletions (Z 4 bp, Po0.001). In survival analysis, patients with low HSP110wt expression (0/1 þ ) showed better diseasefree survival compared with those with high expression (2 þ /3 þ ; P ¼ 0.005). This significance in survival difference was maintained in patients with 5-fluorouracil-based chemotherapy-treated tumors (P ¼ 0.024) and in those with stage III/IV tumors (P ¼ 0.032). Multivariate analysis confirmed the role of HSP110wt expression as an independent prognostic factor (P ¼ 0.016, hazard ratio ¼ 4.32). In MSI-H colorectal cancer, a low expression of HSP110wt is associated with large HSP110 T 17 deletions and better clinical outcome. Immunohistochemistry of HSP110wt can be a simple and valuable tool for the prognostic and therapeutic stratification of patients with MSI-H colorectal cancer.

KRAS mutation has an adverse prognostic impact on stage II or III CRC treated with adjuvant FOLFOX.

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