The impact of sidedness of colorectal cancer in tumor immunity.

Abstract

584 Background: Clinical and molecular characteristics are different between Right-side and left-sided colorectal cancer (CRC). The aim of this study was to clarify the significance of the correlation of the Sidedness of CRC and tumor immunity. Methods: A total of 116 patients who underwent curative colectomy for stage II/III CRC were included in this study. The expression of PD-1, PD-L1, FoxP3, TGF-b, and IDO was examined by immunohistochemistry and the relationship of sidedness to several prognostic factors was examined. Results: In clinicopathological factors, there were no significant difference between right sided and left sided CRC except for differentiation. Regarding tumor immunity, there were no significant difference in PD-1 and IDO expression. However, Fox P3 (right side 72% vs. left side 59%) and TGFβ (right side 72% vs. left side 57%) tended to be highly expressed in right side(p < 0.1). PDL1 was significantly highly expressed in right side(right side 65% vs. left side 35%, p < 0.05). In OS and DFS, the patients with right sided tumor tended to have poor prognosis compared with left side (p < 0.1). The PD-L1 positive patients of right-sided tumor had poor prognosis (p < 0.05). Conclusions: Sidedness is associated with tumor immunity in colorectal cancer.