DNA repair gene XPD Polymorphisms and cancer risk: A meta-analysis based on 56 case-control studies

Genetic variations in the XPD gene may increase cancer susceptibility by affecting the capacity for DNA repair. Several studies have investigated this possibility; however, the conclusions remain controversial. Therefore, we did a systematic review and executed a meta-analysis to explore the association. From 56 studies, a total of 61 comparisons included 25,932 cases and 27,733 controls concerning the Lys(751)Gln polymorphism; 35 comparisons included 16,781 cases and 18,879 controls in the case of Asp(312)Asn were reviewed. In this analysis, small associations of the XPD Lys(751)Gln polymorphism with cancer risk for esophageal cancer [for Lys/Gln versus Lys/Lys: odds ratio (OR), 1.34; 95% confidence interval (95% CI), 1.10-1.64; for Gln/Gln versus Lys/Lys: OR, 1.61; 95% CI, 1.16-2.25] and acute lymphoblastic leukemia (for Gln/Gln versus Lys/Lys: OR, 1.83; 95% Cl, 1.21-2.75) are revealed. Overall, individuals with the Gln/Gln genotype have a small cancer risk compared with Lys/Lys genotype for the reviewed cancer in total (OR, 1.10; 95% Cl, 1.03-1.16). Subtle but significant cancer risk was observed for the XPD Asp(312)Asn polymorphism in bladder cancer (for Asp/Asn versus Asp/Asp: OR, 1.24; 95% CI, 1.06-1.46). No significant associations were found for other cancers separately and all the reviewed cancer in total assessed for the Asp(312)Asn polymorphism. Our study suggests that XPD is a candidate gene for cancer susceptibility regardless of environmental factors.