The prognostic value of TILs in stage III colon cancer must consider sidedness

Abstract

Sidedness has long been identified as a prognostic and predictive marker in metastatic colon cancer.1,2 This is not unexpected, since the colon is a large organ, with diverse embryogenic origin. Whereas the cecum, ascending colon, and most of the transverse colon derives from midgut, supplied by the superior mesenteric artery, the left part of the transverse colon, descending sigmoid, and rectum derives from hindgut, supplied by the inferior mesenteric artery.3 Possibly because of these embryogenic differences, right and left colon also differ in expression profile, immune response, microbiota, and may be differentially affected by other environmental exposures that increase risk for colorectal cancer (CRC) such as smoking, alcohol, and meat consumption.