e15100 Background: Cancer treatment has entered the era of immune checkpoint inhibitors (ICI), but different tumors have different responses to ICI drugs. For example, non-small cell lung cancer and melanoma have higher response rates to ICIs than colorectal cancer and liver cancer patients. Previous studies have shown that tumor immune microenvironment have a great impact on the efficacy of ICI. Methods: This study retrospectively included pan-cancer patient specimens, using multiple fluorescent labeling immunohistochemistry to explore the differences in the immune microenvironment of different tumors. Shapiro-Wilk was used for normality test, and ANOVA or Kruskal Wallis test was used according to the results. Two-sided P < 0.05 was considered a significant difference. Results: The study included 308 patients, including 119 (38.6%) NSCLC patients, 72 (23.4%) Colorectal cancer patients, 51 (16.6%) Hepatobiliary cancer patients and 66 (21.4%) Others types of cancer patients. Among them, there was 192 (62.3%) Male, and 116 (37.7%) Female, and the median age was 57 (50-66). The proportion of CD8+ T cells and natural killer cell in tumor was statistically different. The proportion of CD8+ T cells in NSCLC, Colorectal cancer, Hepatobiliary cancer and others was 2.16%, 1%, 1.77% and 2.63%, p < 0.01; the proportion of natural killer cell was 16.44 %, 4.91%, 5.58% and 3.29%, p < 0.01. Conclusions: Different tumor types have different immune microenvironments. These results may provide valuable clues for future ICI trail design.
