Lack of association between the XPD Lys751Gln polymorphism and colorectal cancer risk: a meta-analysis

Tao Zhang,1,* Dong-ming Zhang,2,* Da Zhao,1 Xiao-ming Hou,1 Shou-cheng Ma,1 Xiao-jun Liu1 1Department of Oncology, The First Hospital of Lanzhou University, The Branch Hospital of Donggang, Lanzhou, 2Department of Oncology, The Second People's Hospital of Pingliang, Pingliang, People's Republic of China *These authors contributed equally to this work Background: The xeroderma pigmentosum complementary group D (XPD) gene has been linked to the development of colorectal cancer (CRC) through disruption of DNA repair. Several studies have suggested that the XPD polymorphism Lys751Gln is associated with an increased risk of developing CRC. However, previous results remain inconclusive. Herein, we performed a meta-analysis to evaluate the potential for this relationship. Methods: Relevant studies were retrieved from the PubMed database. Strict selection and exclusion criteria were determined, and the odds ratio with a 95% confidence interval was used to assess the strength of associations. The fixed or random effects model was selected on the basis of heterogeneity tests among studies. Publication bias was estimated using funnel plots and Egger's regression test. Results: The meta-analysis included 2,961 cases and 4,539 controls from eleven studies. The results indicated that the XPD Lys751Gln polymorphism had no association with CRC risk for all genetic models (Gln-Gln versus Lys-Lys, P=0.477; Lys-Gln versus Lys-Lys, P=0.283; Lys-Gln + Gln-Gln versus Lys-Lys, P=0.562), even when compared within subgroups based on ethnicity and source of controls. Conclusion: Based on the results of our meta-analysis, there is no evidence of a link between the XPD Lys751Gln polymorphism and risk of CRC. Keywords: XPD Lys751Gln polymorphism, colorectal cancer risk, meta-analysis