ABSTRACT
Objective Type 2 diabetes increases the risk of colorectal cancer and reduces the survival rate of the patients. Therefore, analyzing the characteristics of colorectal cancer in patients with type 2 diabetes may help to develop precise medical measures and to improve the prognosis of patients. Methods The pathological characteristics of 123 colorectal cancer cases with or without type 2 diabetes were analyzed. In addition, PCR and pyrosequencing method were used to test the common gene mutation status of colorectal cancer, including KRAS( codons 12, 13, 61, and 146) , BRAF( codon 600) , and PIK3CA ( exons 9 and 20) , in order to investigate the molecular characteristics of colorectal cancer in diabetic patients which may provide some clues to clinical decision. Results The mean age and body mass index of patients with diabetes were higher than those of patients without diabetes, but there was no difference in the location, the degree of cell differentiation and the grade of colorectal cancer between these 2 groups. The rate of PIK3CA mutation in patients with type 2 diabetes mellitus, especially in patients with long term type 2 diabetes was significantly higher than that in patients without diabetes (28.6％vs 10.3％, P<0.05). There was no significant difference between the two groups in common BRAF and KRAS mutation sites. Conclusion Diabetes does not alter the clinical pathological characteristics of colorectal cancer, but long course type 2 diabetes increases PIK3CA mutation rate. Therefore, using medicine targeting PIK3CA gene mutation may help to improve the prognosis of patients.