Ahn B, Chae Y-S, Kim CH, Lee Y, Lee JH, Kim JY. Tumor microenvironmental factors have prognostic significances in advanced gastric cancer. APMIS 2018; 126: 814-821.Tumor microenvironment is important in the progression and survival of cancer cells. We evaluated the prognostic significance of tumor stroma percentage (TSP), Klintrup-M€ akinen (KM) grade, which reflects the density of inflammatory cells of the tumor, and Glasgow microenvironment score (GMS), a combination of TSP and KM grade, in advanced gastric cancers. A total of 196 pT3 and pT4 gastric cancers were histologically evaluated using TSP, KM grade, and GMS. These were correlated with other clinicopathologic factors including patients' survival. High TSP (78 cases), low KM grade (124 cases), and higher GMS (score 0, 72 cases; 1, 53 cases; and 2, 71 cases) were correlated with poor differentiation, diffuse type, presence of lymphovascular invasion, perineural invasion, and lymph node metastasis. High TSP was significantly correlated with low KM grade (p < 0.001). High TSP (HR, 3.079, 95% CI, 1.612-5.883, p = 0.001), low KM grade (3.201, 1.774-5.776, p < 0.001), and higher GMS (12.274,, p < 0.001) were independent poor prognostic factors. TSP, KM grade, and GMS are significantly associated with clinicopathologic behavior and patients' survival. Assessing these factors is a feasible and cost-effective way to identify tumor microenvironment with different biological features and prognosis of gastric cancer patients.