XPD Lys(751)Gln and Asp (312)Asn polymorphisms and bladder cancer risk: a meta-analysis.

Studies on the polymorphisms of Xeroderma Pigmentosum Group D (XPD) have shown inconclusive trends in the risk of bladder cancer. The purpose of this study is to evaluate the role of XPD single nucleotide polymorphisms in bladder cancer susceptibility. We performed a meta-analysis on all available studies, which included 5,368 and 6,683 XPD Lys(751)Gln cases and controls and 3,220 and 4,391 Asp(312)Asn cases and controls, respectively. Overall, Significant risk effects of Lys(751)Gln genotype was found under recessive model contrast [Gln/Gln vs. (Gln/Lys + Lys/Lys)] [P = 0.04, OR = 1.12; 95% CI (1.01, 1.26)], and subtle but insignificantly increased risks between Lys(751)Gln and bladder cancer were observed under allele contrast (Gln vs. Lys) and homologous contrast (Gln/Gln vs. Lys/Lys) in all subjects. The (751)Gln allele had no significant effect on bladder cancer in all subgroups (Asian, Caucasian and USA). Significant risk effects of Asp(312)Asn polymorphism on bladder susceptibility were observed in all subjects under all genetic contrasts, however, stratified analyses showed that the (312)Asn allele showed different risk effects in USA and Caucasian. The Gln/Gln genotype acts as a risk factor in its association with bladder cancer, and the effect of Lys(751)Gln polymorphism on bladder susceptibility should be studied with larger, stratified population; the (312)Asn allele has an important role in the etiology of bladder cancer whereas the ethnic background should be carefully concerned in further studies.