NBS1 Glu185Gln polymorphism and cancer risk: update on current evidence.

A number of studies have investigated the association between NBS1 Glu185Gln (rs1805794, E185Q) polymorphism and cancer risk, but the results remained controversial. Previous meta-analysis found a borderline significant impact of this polymorphism on cancer risk; however, the result might be relatively unreliable due to absence of numerous newly published studies. Thus, we conducted an updated meta-analysis. A systematic search was performed in PubMed and Embase databases until April 9, 2013. The odds ratios were pooled by the fixed-effects/random-effects model in STATA 12.0 software. As a result, a total of 48 case-control studies with 17,159 cases and 22,002 controls were included. No significant association was detected between the Glu185Gln polymorphism and overall cancer risk. As to subgroup analysis by cancer site, the results showed that this polymorphism could increase the risk for leukemia and nasopharyngeal cancer. Notably, the Glu185Gln polymorphism was found to be related to increased risk for urinary system cancer, but decreased risk for digestive system cancer. No significant associations were obtained for other subgroup analyses such as ethnicity, sample size and smoking status. In conclusion, current evidence did not suggest that the NBS1 Glu185Gln polymorphism was associated with overall cancer risk, but this polymorphism might contribute to the risk for some specific cancer sites due to potential different mechanisms. More well-designed studies are imperative to identify the exact function of this polymorphism in carcinogenesis.