Kanno H, et al. Cancer Sci 2020.
Tumor location and immunity play important roles in the progression of colorectal cancer (CRC). This study aimed to investigate the differences in the immunosurveillance pattern between right- and left-sided CRC and analyze their association with clinicopathological features including mismatch repair (MMR) status. We included surgically resected stage II/III CRC cases and evaluated the immunohistochemical findings of HLA class I, HLA class II, PD-L1, PD-1, CTLA-4, CD3, CD4, CD8, TIA-1, T-bet,
GATA3, RORγT, Foxp3, and CD163. A total of 117 patients were included in the analyses; of these, 30 and 87 had right- and left-sided cancer, respectively. Tumor immunity varied according to the tumor location in the overall cohort. Analysis of the tumors excluding those with MMR deficiency also revealed that tumor immunity differed according to the tumor location. In right-sided CC (colon cancer), high expression of Foxp3 (p=0.0055) and TIA-1 (p=0.0396) was associated with significantly better disease-free survival (DFS). High CD8 (p=0.0808) and CD3 (p=0.0863) expression tended to have better DFS. Further, in left-sided CRC, only high PD-L1 expression in the stroma (p=0.0426) was associated with better DFS. In multivariate analysis, high Foxp3 expression in right-sided CC was an independent prognostic factor for DFS (HR, 7.6445; 95% CI, 1.2091-150.35; p=0.0284). In conclusion, the immunosurveillance pattern differs between right- and left-sided CRC, even after adjusting for MMR deficiency.