XPC gene polymorphisms contribute to bladder cancer susceptibility: a meta-analysis

Numerous studies have investigated the association between three polymorphisms (Lys939Gln, Ala499Val and PAT-/+) of Xeroderma pigmentosum group C (XPC) gene and bladder cancer susceptibility; however, the findings are inconclusive. In order to acquire a more precise estimation of the relationship, we performed a meta-analysis based on 10 studies including 3,934 cases and 4,269 controls for Lys939Gln, five studies including 2,113 cases and 2,249 controls for Ala499Val, and seven studies including 2,834 cases and 3,048 controls for PAT-/+ polymorphism. We searched publications from EMBASE, MEDLINE, and Chinese Biomedical. We calculated pooled odds ratio (OR) and 95 % confidence interval (CI) by using either fixed-effects or random-effects model according to the between-study heterogeneity. We found that all studied polymorphisms were individually associated with increased overall cancer risks, as shown by ORs (95 % CIs) below: the Lys939Gln (Gln/Gln vs. Lys/Lys: OR = 1.39, 95 % CI = 1.08-1.79; recessive model: OR = 1.42, 95 % CI = 1.11-1.83; and allele comparing: OR = 1.12, 95 % CI = 1.003-1.24), the Ala499Val (Val/Val vs. Ala/Ala: OR = 1.82, 95 % CI = 1.19-2.79; recessive model: OR = 1.70, 95 % CI = 1.18-2.46; and allele comparing: OR = 1.23, 95 % CI = 1.01-1.50), and the PAT-/+ (+/+ vs. -/-: OR = 1.36, 95 % CI = 1.03-1.79 and recessive model: OR = 1.34, 95 % CI = 1.06-1.70). Furthermore, stratification analyses demonstrated an increased risk for Asian populations as to the Lys939Gln and PAT-/+ whereas for Caucasian populations as to the Ala499Val polymorphism in the homozygous and recessive models. Despite some limitations, this meta-analysis suggests that XPC polymorphisms are associated with bladder cancer risk, but this association warrants further validation in well-designed studies with large sample sizes.