Correlation of Blood T-Cells to Intratumoural Density and Location of CD3+ and CD8+ T-Cells in Colorectal Cancer

Aim: To test the feasibility of conducting parallel analyses of circulating T-cells in blood and intratumoural T-cells in colorectal cancer. A pre-operative ‘liquid biopsy’ to determine immune status would facilitate clinical decision-making. Materials and Methods: A total of 18 patients with stage I-III colorectal cancer (CRC) were included. Blood was analyzed for T-cell type (CD3⁺, CD4⁺ and CD8⁺) and count using flow cytometry. Intratumoural T-cells were stained using immunohistochemistry and quantified by digital pathology. Tumour location was defined as invasive front (IF) or tumour center (TC). Results: The number of CD3⁺ and CD4⁺ T-cells in pre-surgical blood samples correlated with the number of CD3⁺ T-cells found in the IF (Spearman ϱ=0.558, p<0.05 and 0.598, p<0.01 respectively) and CD3⁺ in the TC (ϱ=0.496, p<0.05, and ϱ=0.637, p<0.01, respectively). A strong correlation was found between CD4⁺ cells in blood and CD8⁺ T-cells found in the TC and IF (ϱ=0.602 and ϱ=0.591, p<0.01). Conclusion: There is a correlation between blood CD3⁺ and CD4⁺ T-cells and the T-cells found at the TC and IF.