The effect of XPD polymorphisms on digestive tract cancers risk: a meta-analysis.
BACKGROUND
The Xeroderma pigmento-sum group D gene (XPD) plays a key role in nucleotide excision repair. Single nucleotide polymorphisms (SNP) located in its functional region may alter DNA repair capacity phenotype and cancer risk. Many studies have demonstrated that XPD polymorphisms are significantly associated with digestive tract cancers risk, but the results are inconsistent. We conducted a comprehensive meta-analysis to assess the association between XPD Lys751Gln polymorphism and digestive tract cancers risk. The digestive tract cancers that our study referred to, includes oral cancer, esophageal cancer, gastric cancer and colorectal cancer.


METHODS
We searched PubMed and EmBase up to December 31, 2012 to identify eligible studies. A total of 37 case-control studies including 9027 cases and 16072 controls were involved in this meta-analysis. Statistical analyses were performed with Stata software (version 11.0, USA). Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association.


RESULTS
The results showed that XPD Lys751Gln polymorphism was associated with the increased risk of digestive tract cancers (homozygote comparison (GlnGln vs. LysLys): OR = 1.12, 95% CI = 1.01-1.24, P = 0.029, P heterogeneity = 0.133). We found no statistical evidence for a significantly increased digestive tract cancers risk in the other genetic models. In the subgroup analysis, we also found the homozygote comparison increased the susceptibility of Asian population (OR = 1.28, 95% CI = 1.01-1.63, P = 0.045, P heterogeneity = 0.287). Stratified by cancer type and source of control, no significantly increased cancer risk was found in these subgroups. Additionally, risk estimates from hospital-based studies and esophageal studies were heterogeneous.


CONCLUSIONS
Our meta-analysis suggested that the XPD 751Gln/Gln genotype was a low-penetrate risk factor for developing digestive tract cancers, especially in Asian populations.
Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Haina
H
Du
Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Nannan
N
Guo
Department of Gastrointestinal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Bin
B
Shi
Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Qian
Q
Zhang
Department of Oncology, The first people's Hospital of Zhangjiagang City, Suzhou, China.
Zhipeng
Z
Chen
Department of Gastrointestinal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Kai
K
Lu
Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Yongqian
Y
Shu
Department of Gastrointestinal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Tao
T
Chen
Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Lingjun
L
Zhu
D044466:Asian People / Q000235:genetics; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000208:ethnology / Q000235:genetics*; D004938:Esophageal Neoplasms / Q000208:ethnology / Q000235:genetics*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000208:ethnology / Q000235:genetics*; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D009062:Mouth Neoplasms / Q000208:ethnology / Q000235:genetics*; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000208:ethnology / Q000235:genetics*; D044465:White People / Q000235:genetics; D051759:Xeroderma Pigmentosum Group D Protein / Q000235:genetics*
D051759:Xeroderma Pigmentosum Group D Protein; C497292:ERCC2 protein, human