1Department of Medical Genetics, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
2Stem cell biology research center, Yazd reproductive science Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Dear editor We read with great interest the recent article by Namazi and colleagues, “association between the XRCC3 Thr241Met polymorphism and risk of colorectal cancer: a meta-analysis of 5,193 cases and 6,645 controls”(Namazi et al., 2015). There are some important negative points decrease the reliability of the article. Firstly, some contradictory findings exist in this meta-analysis. The author found a significant association between the XRCC3 Thr241Met polymorphism and colorectal cancer under the overall dominant and heterozygous model in Caucasian descent. Our review demonstrated inconsistent results in texture (CC+CT vs. TT: OR=0.575, 95%CI=0.498-1.665, P<0.001, Pheterogeneity=0.00, I2=83%) and diagram of overall dominant model (CC+CT vs. TT: OR=0.904, 95%CI=0.796-1.027, P=0.120). On the other hand, in a stratified analysis by ethnicity, the P value of heterozygous model in Caucasian descent is more than 0.05 (CT vs. TT: OR=0.929, 95%CI=0.806-1.070, P=0.308, Pheterogeneity=0.002, I2=57%). Therefore, it seems to exist no significant association between the XRCC3 Thr241Met polymorphism and colorectal cancer under mentioned genetic models. Moreover, the author reported that the dominant and allelic genetic models of the XRCC3 Thr241Met polymorphism were significantly correlated with increasing risk of CRC in Asian population (Dominant model: CC+CT vs. TT: OR=0.609, 95%CI=0.411-0.902, P=0.013, Pheterogeneity=0.54, I2=0.00%; Allelic model: C vs. T: OR=0.708, 95%CI=0.605-0.829, P=0.000, Pheterogeneity=0.000, I2=92%). Conversely, the OR of dominant and allelic models in Asian descent represent decreasing CRC risk.