The Exonuclease 1 Glu589Lys Gene Polymorphism and Cancer Susceptibility: Evidence Based on a Meta-analysis

Background: Published studies on the association between the exonuclease 1 (EXO1) Glu589Lys polymorphismand cancer susceptibility have yielded conflicting results. Thus, a meta-analysis of published studies was performedto assess the possible association. Materials and
Methods: All eligible case-control studies published up to January2013 on the association between the EXO1 Glu589Lys polymorphism and cancer susceptibility were identified bysearching PubMed, Web of Science, Science Direct and hand search. Either fixed-effect or random-effect modelswere used to calculate pooled odds ratios (ORs) with 95% confidence intervals (CIs) using the ComprehensiveMeta-Analysis software version 2.2.
Results: A total of 4,391 cancer cases and 4,339 controls from 10 studieswere included. Overall, no significant association between the EXO1 Glu589Lys polymorphism and cancersusceptibility was observed in either genetic model. However; in subgroup analyses by cancer type, a significantassociation between EXO1 Glu589Lys and lung cancer risk was found (Lys vs Glu: OR=1.23, 95%CI=1.07-1.41, pheterogeneity=0.05). Further, subgroup analysis by ethnicity indicated that there was a statistically increasedcancer risk in Asians (Lys vs Glu: OR=1.42, 95%CI=1.30-1.55, pheterogeneity=0.07; Lys/Lys vs Glu/Glu: OR=1.93,95%CI=1.20-3.12, pheterogeneity=0.01; Lys/Lys+Glu/Lys vs Glu/Glu: OR=1.52, 95%CI=1.37-1.68, pheterogeneity=0.42;Lys/Lys vs Glu/Lys+Glu/Glu: OR=1.68, 95%CI=1.07-2.65, pheterogeneity=0.02). However, significant association wasabsent in Caucasians.
Conclusions: This meta-analysis suggests, for the first time, that the EXO1 Glu589Lyspolymorphism is not associated with overall cancer susceptibility, although marginal associations were found forlung cancer and Asian subgroups. Additional well-designed studies with larger sample size focusing on differentethnicities and cancer types are needed to confirm these findings.