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 polymorphism and cancer susceptibility have yielded conflicting results. Thus, a meta-analysis of published studies was performed to assess the possible association. MATERIALS AND METHODS All eligible case-control studies published up to January 2013 on the association between the EXO1 Glu589Lys polymorphism and cancer susceptibility were identified by searching PubMed, Web of Science, Science Direct and hand search. Either fixed-effect or random-effect models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (CIs) using the Comprehensive Meta-Analysis software version 2.2. RESULTS A total of 4,391 cancer cases and 4,339 controls from 10 studies were included. Overall, no significant association between the EXO1 Glu589Lys polymorphism and cancer susceptibility was observed in either genetic model. However; in subgroup analyses by cancer type, a significant association between EXO1 Glu589Lys and lung cancer risk was found (Lys vs Glu: OR=1.23, 95%CI=1.07- 1.41, p heterogeneity=0.05). Further, subgroup analysis by ethnicity indicated that there was a statistically increased cancer risk in Asians (Lys vs Glu: OR=1.42, 95%CI=1.30-1.55, p heterogeneity=0.07; Lys/Lys vs Glu/Glu: OR=1.93, 95%CI=1.20-3.12, p heterogeneity=0.01; Lys/Lys+Glu/Lys vs Glu/Glu: OR=1.52, 95%CI=1.37-1.68, p heterogeneity=0.42; Lys/Lys vs Glu/Lys+Glu/Glu: OR=1.68, 95%CI=1.07-2.65, p heterogeneity=0.02). However, significant association was absent in Caucasians. CONCLUSIONS This meta-analysis suggests, for the first time, that the EXO1 Glu589Lys polymorphism is not associated with overall cancer susceptibility, although marginal associations were found for lung cancer and Asian subgroups. Additional well-designed studies with larger sample size focusing on different ethnicities and cancer types are needed to confirm these findings.