Abstract:Objective To compare the biological characteristics of left- and right-sided colon cancers and explore the clinical significance of commonly used pathological markers. Methods A retrospective analysis was performed on the clinical data of 73 patients with left-sided colon cancer (group A) and 67 patients with right-sided colon cancer (group B), who were first diagnosed in Zhongda Hospital and Jiangbei People′s Hospital from January 2014 to December 2015. The biological characteristics and the clinical significance of common pathological markers were compared between two groups. Results There was a significant difference in gender between two groups (P<0.05). The majority of patients with left-sided colon cancer were males (64. 38%), and the majority of patients with right-sided colon cancer were females (56.72%). There were no significant differences in age and family history (all P>0.05). Compared to patients with right-sided colon cancer, The incidence rates of bloody stool and change of stool habits were higher, while the incidence rates of abdominal pain, emaciation and anemia were less in left-sided colon cancer patients compared to right-sided colon cancer patients (all P<0.05). There was no significant difference in the length of disease history between two groups (P>0.05). Left-sided colon cancer was mainly composed of moderately differentiated adenocarcinoma, and right-sided colon cancer was mainly composed of moderately and poorly differentiated adenocarcinoma. Compared with left-sided colon cancer, the proportion of mucinous type and tumor′s maximum diameter ≥5 cm was significantly higher, and the proportion of ulcerative type was lower in right-sided colon cancer (all P<0.05). There were no significant differences in tumor staging, tissue infiltration, nerve invasion, intravascular cancer thrombus between two groups (all P>0.05). During 1 to 3 years postoperative follow-up, the poor prognosis rates of patients with left-sided and right-sided colon cancers were 16.44% and 11. 94% respectively (P>0.05), and 1-year mortality rates were 1. 37% and 1. 49%, respectively (P>0.05). There were significant differences in expression levels of immunohistochemical markers such as MutL-homo-logue1 (MLH1), MSH2 and P53 between two groups (all P<0.05), but no differences in the positive levels of cyclooxygenase (COX-2), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER-2), estimated glomerular filtration rate (EGFR), Ki-67, etc. (all P>0.05). All patients were accompanied by high expressions of COX-2 and EGFR. Conclusion There are significant differences in gender, clinical symptoms and pathological types between left- and right-sided colon cancer patients, and all patients are associated with high expressions of COX-2 and EGFR. The expression levels of MLH1, MSH2 and P53 in left-sided colon cancer are significantly higher than those in right-sided colon cancer, which is of great significance for the precise treatment of colon cancer guided by molecular markers.