TERT rs2736100 polymorphism contributes to lung cancer risk: a meta-analysis including 49,869 cases and 73,464 controls

Some studies investigated the association of TERT rs2736100 polymorphism with lung cancer (LC). But the results were not consistent. We performed a meta-analysis to examine the association between rs2736100 and LC. Databases including PubMed, EMBASE, Wanfang, and China National Knowledge Infrastructure (CNKI) were searched. Data were extracted, and pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated. A total of 19 studies including 49,869 cases and 73,464 controls were involved in this meta-analysis. Overall, a significant association between TERT rs2736100 polymorphism and LC risk was observed (OR?=?1.23, 95 % CI 1.18–1.28, P?<?0.00001). This polymorphism was also significantly associated with LC risk in Asians (OR?=?1.27, 95 % CI 1.22–1.33, P?<?0.00001), Caucasians (OR?=?1.14, 95 % CI 1.10–1.18, P?<?0.00001), female patients (OR?=?1.37, 95 % CI 1.24–1.51, P?<?0.00001), male patients (OR?=?1.23, 95 % CI 1.15–1.31, P?<?0.00001), adenocarcinoma patients (OR?=?1.35, 95 % CI 1.28–1.41, P?<?0.00001), squamous cell carcinoma patients (OR?=?1.13, 95 % CI 1.04–1.21, P?=?0.002), small cell lung cancer patients (OR?=?1.09, 95 % CI 1.03–1.16, P?=?0.004), current smokers (OR?=?1.22, 95 % CI 1.17–1.27, P?<?0.00001), former smokers (OR?=?1.14, 95 % CI 1.08–1.21, P?<?0.0001), and never smokers (OR?=?1.37, 95 % CI 1.31–1.43, P?<?0.00001), respectively. This meta-analysis suggested that TERT rs2736100 polymorphism was a risk factor for LC.     

Association between tumor necrosis factor-α rs1800629 polymorphism and risk of gastric cancer: a meta-analysis

Gastric cancer is mainly initiated by inflammation and chronic superficial gastritis, and tumor necrosis factor-α (TNF-α) is an inflammatory cytokine which plays an important role in the inflammation. TNF-α rs1800629 G/A polymorphism was proposed to be associated with gastric cancer risk, but previous studies on Caucasians reported conflicting results. We performed a meta-analysis to comprehensively assess the association between TNF-α rs1800629 polymorphism and gastric cancer risk in Caucasians. The pooled odds ratio (OR) with 95 % confidence interval (95 % CI) was calculated to assess the association. Eleven case–control studies with 7,427 subjects were finally included into the meta-analysis. Overall, TNF-α rs1800629 polymorphism was significantly associated with the increased risk of gastric cancer under four genetic comparison models (A versus G: OR?=?1.32, 95 % CI 1.12–1.56, P?=?0.001; AA versus GG: OR?=?1.76, 95 % CI 1.37–2.26, P?<?0.001; AA versus GG/GA: OR?=?1.62, 95 % CI 1.27–2.07, P?<?0.001; AA/GA versus GG: OR?=?1.35, 95 % CI 1.14–1.60, P?=?0.001). Meta-analysis of those studies with high quality showed that TNF-α rs1800629 polymorphism was still significantly associated with the increased risk of gastric cancer under four genetic comparison models. There was no risk of publication bias in the meta-analysis. The meta-analysis suggests that TNF-α rs1800629 polymorphism is associated with the increased risk of gastric cancer in Caucasians.     

Association of X-ray repair cross-complementing group 1 promoter rs3213245 polymorphism with lung cancer risk

X-ray repair cross-complementing group 1 (XRCC1) is a major DNA repair protein in the base excision repair pathway. XRCC1 rs3213245 is a functional polymorphism in the XRCC1 gene promoter region which results in decreased DNA repair capacity. Previous studies investigating the association of XRCC1 rs3213245 polymorphism with lung cancer risk reported conflicting results. A meta-analysis of published studies was performed to provide a comprehensive assessment of the association. The pooled odds ratio (OR) with its 95 % confidence interval (95 % CI) was calculated to assess the association. Subgroup analysis was performed by ethnicity. Finally, six studies with a total of 3,208 cases and 3,505 control studies were included into our meta-analysis. The pooled results showed that there was a significant association between XRCC1 rs3213245 polymorphism and lung cancer risk (allele model: OR?=1.31, 95 % CI 1.13–1.51, P?<?0.001; homozygote model: OR?=?1.42, 95 % CI 1.13–1.79, P?=?0.003; recessive model: OR?=?1.39, 95 % CI 1.13–1.71, P?=?0.002; dominant model: OR?=?1.31, 95 % CI 1.17–1.47, P?<?0.001). Subgroup analysis by ethnicity showed that the association was still significant in both Asians (all P values less than 0.05) and Caucasians (recessive model: OR?=?1.26, 95 % CI 1.01–1.59, P?=?0.045). Thus, there is a significant association of XRCC1 rs3213245 polymorphism with lung cancer risk.     

Polymorphisms in the MDM2 gene and risk of malignant bone tumors: a meta-analysis

There are several studies published to assess the associations of murine double minute 2 (MDM2) genetic polymorphisms with risk of malignant bone tumors, but they reported contradictory results and failed to confirm a strong and consistent association. To assess the evidence regarding the associations of MDM2 genetic polymorphisms with the risk of malignant bone tumors, we conducted a meta-analysis of epidemiological studies. The pooled odds ratio (OR) with its 95 % confidence intervals (95 % CI) was used to assess these possible associations. Four studies with a total of 3,958 individuals were finally included the meta-analysis. Meta-analysis of two studies on MDM2 SNP309 polymorphism showed that MDM2 SNP309 polymorphism was associated with an increased risk of malignant bone tumors (G versus T: OR?=?1.72, 95 % CI 1.35–2.20, P?<?0.001; GG versus TT: OR?=?2.64, 95 % CI 1.59–4.39, P?<?0.001; GG/GT versus TT: OR?=?1.87, 95 % CI 1.33–2.62, P?<?0.001; GG versus TT/GT: OR?=?2.20, 95 % CI 1.38–3.51, P?=?0.001). Meta-analysis of those two studies on MDM2 rs1690916 polymorphism showed that MDM2 rs1690916 minor allele A was associated with decreased risk of malignant bone tumors (OR?=?0.60, 95 % CI 0.46–0.77, P?<?0.001). Meta-analyses of available data show that there are significant associations of MDM2 SNP309 polymorphism and MDM2 rs1690916 polymorphism with malignant bone tumors.     

Association between epidermal growth factor gene rs4444903 polymorphism and risk of glioma

The development of glioma is a complex process which may be influenced by many factors including the epidermal growth factor (EGF) gene polymorphism. Previous studies showed that EGF rs4444903 polymorphism could result in increased risk of tumorigenesis in multiple human cancers, but published data regarding the association between EGF rs4444903 polymorphism and glioma risk were inconsistent. To derive a more precise estimation of the association between EGF rs4444903 polymorphism and glioma risk, we performed a systematic review and meta-analysis of previous published studies. PubMed, Embase, and the Wanfang databases were systematically searched to identify relevant studies. Odds ratios (ORs) and 95 % confidence intervals (95 % CIs) were calculated to assess the strength of the association. Ten published studies with 1,891 glioma cases and 2,836 controls were finally included into the study. Overall, there was a significant association between EGF rs4444903 polymorphism and glioma risk in all four genetic models (the allele model: OR?=?1.25, 95 % CI 1.15–1.37, P?<?0.001; the codominant model: OR?=?1.65, 95 % CI 1.36–1.99, P?<?0.001; the dominant model: OR?=?1.27, 95 % CI 1.12–1.44, P?<?0.001; the recessive model: OR?=?1.48, 95 % CI 1.25–1.75, P?<?0.001). Subgroup analyses by ethnicity showed that EGF rs4444903 polymorphism resulted in a higher risk of glioma among both Asians and Caucasians. In conclusion, the results suggest that there is a significant association between EGF rs4444903 polymorphism and glioma risk, and genotypes of EGF rs4444903 mutation contribute to increased host susceptibility to glioma.     

PLCE1 rs2274223 A>G polymorphism and cancer risk: a meta-analysis

Phospholipase C epsilon 1 gene (PLCE1) encodes a phospholipase enzyme which regulates various physiological processes (cell growth, differentiation, and apoptosis) and is supposed to play a critical role in carcinogenesis. Recently, a single nucleotide polymorphism (rs2274223 A>G) in PLCE1 was reported as a novel susceptibility locus for esophageal and gastric cancers by genome-wide association studies performed in Chinese population. However, individual association studies replicating this finding showed inconclusive results. Therefore, we performed a meta-analysis of eligible studies to derive precise estimation of the association of PLCE1 rs2274223 A>G polymorphism with cancer risk. We performed pooled analysis of 12 case–control studies including 7,622 cases and 9,555 controls. Odds ratios and 95 % confidence interval were calculated to assess strength of association in overall studies and in subgroup analysis stratified by ethnicity, cancer types, and source of controls. All statistical analyses were performed by MIX 2.0 software. We found that PLCE1 rs2274223 A>G polymorphism was significantly associated with increased risk of cancer in log additive/dominant model and at allele level (GG vs. AA: OR?=?1.24, 95 % CI?=?1.01–1.53, P?=?0.039; AG vs. AA: OR?=?1.24, 95 % CI?=?1.16–1.32, P?<?0.001; AG?+?GG vs. AA: OR?=?1.22, 95 % CI?=?1.12–1.34, P?<?0.001; and G vs. A allele: OR?=?1.15, 95 % CI?=?1.05–1.25, P?=?0.002). Further, stratified analysis showed elevated risk of only gastric and esophageal tumors. Sub-group analysis based on ethnicity suggests PLCE1 polymorphism conferred significant risk among Asian (Chinese) but not in Caucasian. In conclusion, PLCE1 rs2274223 polymorphism may be used as potential biomarker for cancer susceptibility particularly for esophageal/gastric cancer and for the Chinese population.     

Cleft lip and palate transmembrane protein 1 rs31489 polymorphism is associated with lung cancer risk: a meta-analysis

The potentially functional polymorphism, rs31489, in the promoter region of cleft lip and palate transmembrane protein 1 (CLPTM1L) gene has been implicated in cancer risk. However, individual published studies showed inconclusive results. To obtain a more precise estimate of the association between CLPTM1L rs31489 and risk of lung cancer, we performed a meta-analysis. Summary odds ratios (ORs) and corresponding 95 % confidence intervals (CIs) were estimated using random-effects models. Ten individual case–control studies in eight publications with 20,680 cases and 28,330 controls were included. Overall, the variant genotypes were associated with a significantly increased lung cancer risk in different genetic models (CC + AC vs. AA: OR?=?1.20, 95 % CI 1.12–1.28, P?<?0.001; CC vs. AC + AA: OR?=?1.15, 95 % CI 1.07–1.23, P?<?0.001; CC vs. AA: OR?=?1.28, 95 % CI 1.17–1.41, P?<?0.001; CC vs. AC: OR?=?1.11, 95 % CI 1.05–1.17, P?<?0.001; C vs. A: OR?=?1.12, 95 % CI 1.06–1.18, P?<?0.001). In the stratified analyses, the increased lung risk remained for the studies of Caucasian populations. In conclusion, this meta-analysis suggested that CLPTM1L rs31489 was a potential biomarker for lung cancer risk in Caucasians.     

Effects of murine double minute 2 polymorphisms on the risk and survival of osteosarcoma: a systemic review and meta-analysis

Murine double minute 2 (MDM2) plays an important role in the carcinogenesis of many cancers including osteosarcoma. We performed a systemic review and meta-analysis to assess the effects of MDM2 polymorphisms on osteosarcoma risk and survival of patients with osteosarcoma. PubMed, Web of Science, and Wanfang databases were searched for eligible studies on the associations of MDM2 polymorphisms with osteosarcoma risk and survival of patients with osteosarcoma. Pooled odds ratio (OR) or hazard ratio (HR) with 95 % confidence intervals (95 % CIs) was used to assess the effects of MDM2 polymorphisms on osteosarcoma risk and survival of patients with osteosarcoma. Overall, MDM2 rs2279744 polymorphism was associated with a risk of osteosarcoma (allele model, OR?=?1.60, 95 % CI 1.23–2.07, P?<?0.001; codominant model, OR?=?2.47, 95 % CI 1.46–4.19, P?=?0.001; recessive model, OR?=?2.13, 95 % CI 1.32–3.46, P?=?0.002; dominant model, OR?=?1.61, 95 % CI 1.12–2.33, P?=?0.01). MDM2 rs1690916 polymorphism was also associated with a risk of osteosarcoma (OR?=?0.60, 95 % CI 0.46–0.77, P?<?0.001). However, MDM2 rs2279744 polymorphism was not associated with the overall survival of patients with osteosarcoma (codominant model, HR?=?1.01, 95 % CI 0.53–1.91, P?=?0.98; recessive model, HR?=?1.07, 95 % CI 0.54–2.11, P?=?0.85; dominant model, HR?=?1.04, 95 % CI 0.65–1.66, P?=?0.87). The meta-analysis suggests that MDM2 polymorphisms have some effects on the risk of osteosarcoma but have no effect on the survival of patients with osteosarcoma. Future studies are needed to further assess the effects of MDM2 polymorphisms on the risk and survival of osteosarcoma.     

Tumor necrosis factor-α 238 G/A polymorphism and gastric cancer risk: a meta-analysis

Though many studies were performed to assess the association between tumor necrosis factor-α (TNF-α) 238 G/A polymorphism and gastric cancer risk, there were no conclusive findings. A meta-analysis of previous published studies was performed to get a comprehensive assessment of the association between TNF-α 238 G/A polymorphisms and gastric cancer. The pooled odds ratios (ORs) and 95 % confidence intervals (95 % CIs) were calculated to assess the association. Fifteen studies with a total of 7,795 participants were finally included into this meta-analysis. Overall, there was an obvious association between TNF-α 238 G/A polymorphism and increased risk of gastric cancer (A vs. G: OR?=?1.32, 95 % CI 1.02–1.72, P?=?0.036; GA vs. GG: OR?=?1.32, 95 % CI 1.01–1.72, P?=?0.042; and AA/GA vs. GG: OR?=?1.34, 95 % CI 1.02–1.76, P?=?0.036). Subgroup analysis by ethnicity showed the statistically significant association between TNF-α 238 G/A polymorphism and gastric cancer was limited to Asian populations (A vs. G: OR?=?1.59, 95 % CI 1.29–1.97, P?<?0.001; GA vs. GG: OR?=?1.63, 95 % CI 1.29–2.04, P?<?0.001; and AA/GA vs. GG: OR?=?1.64, 95 %CI 1.31–2.05, P?<?0.001), and there was no obvious association in Caucasians. In conclusion, TNF-α 238 G/A polymorphism is significantly associated with increased risk of gastric cancer, especially in Asians.     

Lack of association of XRCC1 rs1799782 genetic polymorphism with risk of pancreatic cancer: a meta-analysis

Emerging evidence suggests that genetic polymorphisms in X-ray repair cross-complementation group 1 (XRCC1) gene could be associated with pancreatic cancer risk. However, previous published studies on the association between XRCC1 rs1799782 genetic polymorphism and pancreatic cancer risk reported inconsistent results. For better understanding of the effects of XRCC1 rs1799782 genetic polymorphism on pancreatic cancer risk, we conducted a meta-analysis of previous published studies by calculating the pooled odds ratio (OR) with a 95 % confidence interval (95 % CI). A total of five eligible studies with 1,144 pancreatic cancer cases and 2,925 controls were eventually enrolled. Overall, we found that the XRCC1 rs1799782 genetic polymorphism was not associated with pancreatic cancer risk in total population under all genetic models (TT vs. CC: OR?=?1.11, 95 % CI 0.76–1.63, P?=?0.583; CT vs. CC: OR?=?1.39, 95 % CI 0.92–2.10, P?=?0.118; TT/CT vs. CC: OR?=?1.39, 95 % CI 0.92–2.10, P?=?0.121; TT vs. CT/CC: OR?=?1.07, 95 % CI 0.73–1.55, P?=?0.743; T vs. C: OR?=?1.31, 95 % CI 0.93–1.86, P?=?0.125). In the subgroup analysis based on ethnicity, there was no statistically significant association between XRCC1 rs1799782 genetic polymorphism and pancreatic cancer risk in Asians/Caucasians under all genetic models (all P values?>?0.05). No publication bias was detected in this study. Our meta-analysis suggests that the XRCC1 rs1799782 genetic polymorphism is not significantly associated with pancreatic cancer risk. Considering the limited sample size and ethnicity enrolled in this meta-analysis, further larger scaled studies are needed to provide a more precise estimation on the association.     

CD95 rs1800682 polymorphism and cervical cancer risk: evidence from a meta-analysis

CD95 is the first death receptor identified and characterized in recent years, and it plays important roles in the molecular network regulating cell death and survival. CD95 rs1800682 polymorphism is a common genetic polymorphism identified in the CD95 gene. Many publications evaluated the association between CD95 rs1800682 polymorphism and cervical cancer risk, but the association remained inconclusive. To provide a more precise estimate on the association, a meta-analysis was carried out. The association between CD95 rs1800682 polymorphism and cervical cancer risk was assessed by calculating the pooled odds ratio (OR) with its 95 % confidence intervals (95 % CI). On the basis of our inclusion criteria, ten studies with a total of 5,481 individuals were included into the meta-analysis. There was obvious heterogeneity among the included studies. Meta-analysis of the ten studies suggested that there was no association between CD95 rs1800682 polymorphism and cervical cancer risk under all four genetic models (allele model: OR?=?1.05, 95 % CI 0.92–1.18, P?=?0.478; homozygous model: OR?=?1.08, 95 % CI 0.83–1.41, P?=?0.550; dominant model: OR?=?1.12, 95 % CI 0.88–1.42, P?=?0.347; recessive model: OR?=?1.00, 95 % CI 0.76–1.31, P?=?0.978). Subgroup analysis by ethnicity suggested that there was no association between CD95 rs1800682 polymorphism and cervical cancer risk in Asians, Caucasians, and Africans. Thus, the meta-analysis suggests that CD95 rs1800682 polymorphism is not associated with cervical cancer risk.     

P53 codon 72 polymorphism and lung cancer risk: evidence from 27,958 subjects

The role of p53 codon 72 polymorphism in the development of lung cancer remains obscure due to inconsistent findings of individual case–control studies published to date. A meta-analysis was conducted to better estimate the association between the p53 codon 72 variant and lung cancer risk. All relevant publications from the PubMed, Embase, Web of Science, and Wanfang databases were retrieved. Based on the inclusion criteria, 39 publications involving 44 independent case–control studies were finally included into this meta-analysis. Data were extracted and the pooled odds ratio (OR) with the corresponding 95 % confidence interval (95 % CI) was calculated. The overall pooled ORs showed no significant relationship of the p53 codon 72 polymorphism with increased or decreased risk of lung cancer in all gene contrast models (OR _{Pro vs. Arg}?=?1.04, 95 % CI?=?0.96–1.13, P _OR?<?0.001; OR _{Pro/Pro vs. Arg/Arg}?=?1.07, 95 % CI?=?0.91–1.25, P _OR?<?0.001; OR _{Arg/Pro vs. Arg/Arg} =1.04, 95 % CI?=?0.94–1.15, P _OR?<?0.001; OR _{Pro/Pro + Arg/Pro vs. Arg/Arg}?=?1.04, 95 % CI?=?0.94–1.16, P _OR?<?0.001; OR _{Pro/Pro vs. Arg/Arg + Arg/Pro}?=?1.07, 95 % CI?=?0.93–1.23, P _OR?<?0.001). According to the ethnicity, no significant association was observed in subgroup analyses of the Asians, Caucasians, Africans and the mixed population. Similar finding was found in subgroup analyses of hospital-based and population-based studies. Concerning the histological types of lung cancer, the p53 codon 72 variant exerts risk effect on the lung carcinogenesis in patients with adenocarcinoma (OR _{Arg/Pro vs. Arg/Arg}?=?1.10, 95 % CI?=?1.00–1.22, P _OR?=?0.048). Additionally, subgroup analysis by the smoking status demonstrated that the p53 codon 72 variant seemed to play a protective role in lung carcinogenesis among the non-smokers but not the smokers in the contrast model of Arg/Pro vs. Arg/Arg (OR _{Arg/Pro vs. Arg/Arg}?=?0.71, 95 % CI?=?0.50–1.00, P _OR?=?0.049). The present meta-analysis suggests the p53 codon 72 polymorphism may weakly modify the risk for lung cancer among the adenocarcinoma patients and non-smokers. Nevertheless, this association needs further confirmation in future studies with high quality.     

Murine double minute 2 rs2279744 polymorphism and hepatocellular carcinoma risk in East Asians: a meta-analysis

Murine double minute 2 (MDM2) is a crucial negative regulator of p53 function through several mechanisms. There are many studies performed to assess the association between MDM2 rs2279744 polymorphism and hepatocellular carcinoma risk, but the impact of MDM2 rs2279744 polymorphism on hepatocellular carcinoma in East Asians is unclear owing to the inconsistent findings from previous studies. We conducted a comprehensive meta-analysis of epidemiological studies to shed some light on these contradicting results. We used pooled odds ratio (OR) with its 95 % confidence intervals (95 % CI) to assess the association. Overall, seven studies with a total of 4,993 subjects were finally included. The meta-analysis suggested that MDM2 rs2279744 polymorphism was significantly associated with increased risk of hepatocellular carcinoma in East Asians (G versus T: OR?=?1.27, 95 % CI 1.06–1.52, P?=?0.01; GG versus TT: OR?=?1.59, 95 % CI 1.11–2.27, P?=?0.01; GG/GT versus TT: OR?=?1.41, 95 % CI 1.07–1.87, P?=?0.02; GG versus TT/GT: OR?=?1.32, 95 % CI 1.08–1.62, P?=?0.008). Sensitivity analysis by excluding low-quality study still suggested that the association above was still significant. Thus, the findings from the meta-analysis support that MDM2 rs2279744 polymorphism is significantly associated with increased risk of hepatocellular carcinoma in East Asians.     

The association between cyclooxygenase-2 1195 G/A polymorphism and hepatocellular carcinoma: evidence from a meta-analysis

Cyclooxygenase-2 (COX-2) is proven to influence the carcinogenesis through immune response suppression, apoptosis inhibition, angiogenesis regulation, and tumor cell invasion. Previous studies assessing the association between COX-2 1195 G/A polymorphism and susceptibility to hepatocellular carcinoma (HCC) reported conflicting results. The objective of the study was to investigate the association between COX-2 1195 G/A polymorphism and HCC by a meta-analysis. PubMed, Embase, Web of Science, and Wangfang databases were searched for studies investigating the association between COX-2 1195 G/A polymorphism and HCC risk. The pooled odds ratio (OR) and its 95 % confidence interval (CI) were used to assess the strength of the association. Five studies with a total of 1,690 HCC cases and 1,961 controls were identified. Meta-analyses of total included studies showed that there was an obvious association between COX-2 1195 G/A polymorphism and HCC risk under two main genetic models (for AA versus GG, fixed-effects OR?=?1.45, 95 % CI 1.15–1.81, P?=?0.001, I ²?=?0.0 %; for AA/GA versus GG, fixed-effects OR?=?1.26, 95 % CI 1.05–1.51, P?=?0.011, I ²?=?0.0 %). Subgroup analysis by ethnicity showed that association was still obvious in Asians under two genetic models (for AA versus GG, fixed-effects OR?=?1.45, 95 % CI 1.16–1.82, P?=?0.001, I ²?=?21.7 %; for AA/GA versus GG, fixed-effects OR?=?1.27, 95 % CI 1.05–1.54, P?=?0.013, I ²?=?0.4 %). The evidence from the meta-analysis supports an association between COX-2 1195 G/A polymorphism and HCC risk in Asians. Further studies with large sample and careful design are needed to identify the possible association in Caucasians.     

Quantitative synthesis of the association between the cytochrome P450 1A1 Ile462Val polymorphism and prostate cancer risk

The association between the cytochrome P450 1A1 (CYP1A1) Ile462Val polymorphism and prostate cancer risk remains inconclusive owing to the conflicting findings from previous studies. To get a more precise estimate of the possible association, we performed the present meta-analysis. We searched the PUBMED, EMBASE, and Wanfang databases for the studies which met the inclusion criteria. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95 % CI) was used to estimate the association between CYP1A1 Ile462Val polymorphism and prostate cancer risk. A total of 13 studies with 2,350 cases and 2,992 controls were included in the meta-analysis. The results indicated that there was an obvious association between CYP1A1 Ile462Val polymorphism and increased risk of prostate cancer (for Val versus Ile: OR?=?1.27, 95 % CI 1.13–1.43, P?<?0.001; for ValVal versus IleIle: OR?=?1.51, 95 % CI 1.14–2.01, P?=?0.004; for ValVal?+?ValIle versus IleIle: OR?=?1.31, 95 % CI 1.14–1.51, P?<?0.001; for ValVal versus IleIle + ValIle: OR?=?1.38, 95 % CI 1.05–1.81, P?=?0.020). Subgroup analyses by ethnicity suggested that CYP1A1 Ile462Val polymorphism was associated with prostate cancer risk in Asians but not in Caucasians. This meta-analysis suggests that there is an association between CYP1A1 Ile462Val polymorphism and increased risk of prostate cancer. More studies with large sample are needed to further assess the association in Caucasians.     

Two DNA repair gene polymorphisms on the risk of gastrointestinal cancers: a meta-analysis

PARP-1 and MGMT play an important role in the DNA repair system and therefore have been implicated in human carcinogenesis. However, the association between the most studied PARP-1 rs1136410: T?>?C and MGMT rs12917: C?>?T polymorphism and risk of gastrointestinal (GI) cancers was reported with inconclusive results. Accordingly, a meta-analysis of 23 published case–control studies was conducted to assess the strength of association using crude odds ratios (ORs) with 95 % confidence intervals (CIs). Overall, the C allele of PARP-1 rs1136410: T?>?C polymorphism was significantly associated with increased susceptibility of GI cancers (homozygote comparison: OR?=?1.43, 95 % CI 1.14–1.81; heterozygote comparison: OR?=?1.18, 95 % CI 1.07–1.29; dominant model: OR?=?1.23, 95 % CI 1.12–1.35; recessive model: OR?=?1.30, 95 % CI 1.04–1.62; allelic comparison: OR?=?1.19, 95 % CI 1.07–1.32). In the subgroup analysis, still obvious associations were found in the Asian population, gastric cancer, and high-quality studies. For MGMT rs12917: C?>?T polymorphism, no obvious associations were found for all genetic models overall. However, in the subgroup analysis, we found that the T allele was significantly associated with reduced colorectal cancer risk for heterozygote (OR?=?0.83, 95 % CI 0.70–0.97) and dominant model (OR?=?0.84, 95 % CI 0.72–0.98). In conclusion, this meta-analysis suggests that the PARP-1 rs1136410: T?>?C polymorphism is a susceptibility factor for GI cancers, but the variant allele of MGMT rs12917: C?>?T polymorphism appears to be a protective factor for colorectal cancer. Large-scale and well-designed case–control studies are necessary to validate the risk identified in the present meta-analysis.     

Association between X-ray repair cross-complementation group 1 rs25487 polymorphism and pancreatic cancer risk

Previous published studies suggested that genetic polymorphisms in DNA repair genes could modify the DNA repair capacity and could be associated with pancreatic cancer risk. However, previous studies on the association between X-ray repair cross-complementation group 1 (XRCC1) rs25487 (Arg399Gln) polymorphism and pancreatic cancer risk reported inconsistent results. To obtain a more precise estimation of the association between XRCC1 rs25487 polymorphism and pancreatic cancer risk, we performed a meta-analysis of previous published studies by calculating the pooled odds ratio (OR) with a 95 % confidence interval (95 % CI). Eight individual studies with 5,542 subjects from six publications were finally included into this meta-analysis. The meta-analysis of total eight studies showed that there was no association between XRCC1 rs25487 polymorphism and pancreatic cancer risk in total population under all four genetic models (Gln versus Arg: OR?=?1.10, 95 % CI 0.95–1.28, P?=?0.199; GlnGln versus ArgArg: OR?=?1.15, 95 % CI 0.93–1.41, P?=?0.191; GlnGln/ArgGln versus ArgArg: OR?=?1.10, 95 % CI 0.97–1.25, P?=?0.127; GlnGln versus ArgArg/ArgGln: OR?=?1.12, 95 % CI 0.92–1.36, P?=?0.253). Subgroup analysis showed that there was no association between XRCC1 rs25487 polymorphism and pancreatic cancer risk in Caucasians, but XRCC1 rs25487 polymorphism was associated with pancreatic cancer risk in Asians (GlnGln/ArgGln versus ArgArg: OR?=?1.24, 95 % CI 1.01–1.53, P?=?0.040). Therefore, the meta-analysis suggests that XRCC1 rs25487 polymorphism is associated with pancreatic cancer risk in Asians. Further studies with more participants are needed to provide a more precise estimation on the association above.     

Association between SOD2 C47T polymorphism and lung cancer susceptibility: a meta-analysis

Lung cancer is one of the most common cancers worldwide, but its etiology is still unclear. Superoxide dismutase 2 (SOD2) plays an essential role in oxidative stress and may be involved in the development of lung cancer. The association between SOD2 C47T polymorphism and lung cancer risk has been widely investigated, but the results of previous studies are contradictory. We conducted a meta-analysis to comprehensively assess the association between SOD2 C47T polymorphism and lung cancer. The association was estimated by odds ratio (OR) with 95 % confidence interval (95 % CI). A total of 10 studies with 5,146 cases and 6,173 controls were identified. The results showed that SOD2 C47T polymorphism was significantly associated with lung cancer (T versus C: OR?=?0.88, 95 % CI?=?0.83–0.93, P?<?0.001; TT versus CC: OR?=?0.74, 95 % CI?=?0.66–0.83, P?<?0.001; TT versus CC/CT: OR?=?0.81, 95 % CI?=?0.73–0.89, P?<?0.001). Subgroup analysis by ethnicity suggested that SOD2 C47T polymorphism was significantly associated with lung cancer in both East Asians and Caucasians. Conclusively, this meta-analysis strongly suggests that SOD2 C47T polymorphism is significantly associated with lung cancer.     

The effect of oxoguanine glycosylase 1 rs1052133 polymorphism on colorectal cancer risk in Caucasian population

Human oxoguanine glycosylase 1 (OGG1) is an important part of the base excision repair pathway in the DNA repair. Numerous epidemiological studies have evaluated the association between OGG1 rs1052133 polymorphism and the risk of colorectal cancer, but the results of these studies from the Caucasian population were conflicting. To derive a more precise assessment on the association between OGG1 rs1052133 polymorphism and risk of colorectal cancer in Caucasian population, we performed a meta-analysis. The odds ratios (OR) with 95 % confidence intervals (CI) were used to assess the strength of the association. Thirteen case–control studies with a total of 4,103 cases and 5,400 controls were finally included into the meta-analysis. Meta-analysis of all 13 studies showed that OGG1 rs1052133 polymorphism was significantly associated with the risk of colorectal cancer in Caucasian population (Cys versus Ser OR?=?1.20, 95 % CI?=?1.03–1.39, P?=?0.02; CysCys versus SerSer OR?=?1.44, 95 % CI?=?1.04–2.00, P?=?0.03; CysCys versus SerSer/SerCys OR?=?1.39, 95 % CI?=?1.15–1.67, P?=?0.0005). In the sensitivity analysis, omitting each study one at a time had no obvious influence on the pooled OR, which confirmed the stability of meta-analysis. The meta-analysis suggests that OGG1 rs1052133 polymorphism is significantly associated with the risk of colorectal cancer in Caucasian population