A Common Promoter Polymorphism (-23HphI) in Insulin Gene and Susceptibility to Colorectal Cancer

With regard to the major role of insulin resistance in colorectal cancer (CRC), this study investigated whether insulin (INS) gene -23HphI variant was associated with susceptibility to CRC risk.
Our study was conducted as a case-control study and 312 cases with CRC and 438 controls were enrolled. All 750 subjects were genotyped for INS gene -23HphI variant using PCR-RFLP method.
There was no significant difference for the -23HphI variant of INS gene in either genotype or allele frequencies between the cases and the controls and this lack of difference remained non-significant even after adjustment for age, BMI, sex, smoking status, regular NSAID use, and family history of CRC. No evidence for the effect modification of the association -23HphI variant and CRC by BMI, sex, or tumor site was also observed. Moreover, the risk of obesity in relation to the -23HphI variant in the controls and the cases was separately analyzed and we observed no significant difference between normal weight (BMI These findings do not support the plausible effect of the INS gene -23HphI variant on CRC risk; nonetheless, our finding requires confirmation and the role of the gene variant in carcinogenesis needs to be further evaluated.