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.     

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.     

Association between FAS 1377G>A polymorphism and breast cancer susceptibility: a meta-analysis

Published studies on the association between FAS 1377G>A polymorphism and breast cancer susceptibility were inconclusive. To derive a more precise assessment of the association, a meta-analysis of published studies was performed. PubMed, Embase, and Web of Science were searched for eligible studies on the association between FAS 1377G>A polymorphism and breast cancer susceptibility. Five studies with a total of 2,905 cases and 3,090 controls were included into the meta-analysis. Overall, FAS 1377G>A polymorphism was significantly associated with increased susceptibility to breast cancer (for AA versus GG: odds ratio (OR)?=?1.39, 95 % confidence interval (95 % CI) 1.12–1.72, P?=?0.003; for AA/GA versus GG: OR?=?1.18, 95 % CI 1.06–1.32, P?=?0.004; for AA versus GG/GA: OR?=?1.28, 95 % CI 1.05–1.56, P?=?0.015). Subgroup analysis by ethnicity found that FAS 1377G>A polymorphism was significantly associated with increased susceptibility to breast cancer in Asians (for AA versus GG: OR?=?1.48, 95 % CI 1.16–1.89, P?=?0.001; for AA/GA versus GG: OR?=?1.24, 95 % CI 1.06–1.46, P?=?0.008; for AA versus GG/GA: OR?=?1.35, 95 % CI 1.08–1.69, P?=?0.008), but the association was not found in Caucasians. Therefore, the findings of the meta-analysis suggest that FAS 1377G>A polymorphism is significantly associated with increased susceptibility to breast cancer in Asians.     

MDM2 SNP309 variation increases cervical cancer risk among Asians

MDM2 T309G polymorphism has been suggested to be a risk factor for a number of cancers. The association of MDM2 T309G genetic variation with cervical cancer risk remains inconclusive. In the present study, we aimed to get a more confidential result by conducting a quantitative meta-analysis. Relevant literature up to October 2013 was searched and screened. Essential information was rigorously extracted for data pooling and analyzing, and then, separate analyses on ethnicity and source of controls were also performed. As a result, four articles including five case–control studies were selected. The overall data failed to show a significant association between MDM2 T309G polymorphism and cervical cancer risk (GG vs TT: odds ratio (OR)?=?1.31; 95 % confidence interval (CI)?=?0.55–3.13; dominant model: OR?=?1.22; 95 % CI?=?0.65–2.31; recessive model: OR?=?1.45; 95 % CI?=?0.79–2.65). However, in the subgroup analysis about ethnicity, increased cancer risk could be shown among Asians (GG vs TT: OR?=?2.15; 95 % CI?=?1.03–4.51; recessive model: OR?=?2.01; 95 % CI?=?1.32–3.06). In conclusion, the results of the present study suggest that homozygous GG alleles of MDM2 T309G polymorphism might be a risk factor for cervical cancer among Asians. Further studies are needed get a more definitive conclusion.     

Study on the association between the Arg194Trp polymorphism in the XRCC1 gene and the risk of hematological malignancies

The association between the Arg194Trp polymorphism in the XRCC1 gene and the risk of hematological malignancies has been extensively investigated. However, the results were inconsistent. The objective of the current study is to investigate the association by meta-analysis. We searched the PubMed, Embase, CNKI, Wanfang, and Weipu databases, covering all studies until Aug. 7, 2013. Statistical analysis was performed by using the RevMan4.2 software and the Stata10.0 software. A total of 20 case–control studies concerning the Arg194Trp polymorphism were indentified from 19 articles. In total analysis, our results suggested that the Arg194Trp polymorphism was not associated with an increased/decreased risk of hematological malignancies (odds ratio (OR)?=?1.01, 95 % confidence interval (CI)?=?0.85–1.22, P?=?0.87 for Arg/Trp+Trp/Trp vs. Arg/Arg). In the subgroup analysis by ethnicity, no significant association was found either among Asians (OR?=?1.04, 95 % CI?=?0.84–1.29, P?=?0.72) or among Europeans (OR?=?1.04, 95 % CI?=?0.72–1.49, P?=?0.83); in the subgroup analyses by cancer types, no significant association was found either among leukemia (OR?=?1.10, 95 % CI?=?0.89–1.35, P?=?0.39) or in lymphoma (OR?=?0.83, 95 % CI?=?0.57–1.22, P?=?0.35). The current meta-analysis indicated that the Arg194Trp polymorphism in the XRCC1 gene might be not a risk factor for hematological malignancies. In the future, more large-scale case–control studies are needed to validate these results.     

Meta-analysis of the association between NQO1 Pro187Ser polymorphism and colorectal cancer in Asians

There were a number of studies performed to assess the association between NQO1 Pro187Ser polymorphism and colorectal cancer risk in Asians, but no consensus was available up to now. We conducted a meta-analysis to assess the association between NQO1 Pro187Ser polymorphism and colorectal cancer risk in Asians. Case–control studies investigating the association between NQO1 Pro187Ser polymorphism and colorectal cancer risk in Asians were searched in Pubmed and Wanfang databases. Pooled odds ratio (OR) and 95 % confidence interval (95 % CI) was calculated. Finally, seven studies involving a total of 2,051 cases and 2,798 controls met the inclusion criteria and were included into the meta-analysis. Overall, there was an obvious association between NQO1 Pro187Ser polymorphism and colorectal cancer risk in Asians (Ser versus Pro: OR?=?1.42, 95 % CI 1.08–1.87, P?=?0.013; SerSer versus ProPro: OR?=?1.86, 95 % CI 1.08–3.19, P?=?0.024; SerSer/ProSer versus ProPro: OR?=?1.61, 95 % CI 1.10–2.35, P?=?0.014; SerSer versus ProPro/ProSer: OR?=?1.46, 95 % CI 1.02–2.10, P?=?0.041). There was low risk of publication bias in the meta-analysis. This meta-analysis suggests that there is an obvious association between NQO1 Pro187Ser polymorphism and colorectal cancer risk in Asians.     

CD243 gene polymorphism significantly associated with breast cancer susceptibility

We aimed to obtain a summary risk estimate for CD243 gene polymorphism associated with breast cancer. A total of nine case–control studies, including 5,073 cancer patients and 7,498 control subjects, were pooled in our fixed effects meta-analysis of the association between CD243 gene polymorphism and risk of breast cancer. All data were analyzed by using Stata software (version 12.0). We found significant risk effects under TT vs. TC?+?CC genetic model [odds ratio (OR)?=?1.09, 95 % confidence interval (CI)?=?1.01–1.18, P?=?0.516], but not in other comparisons. Stratifying the pooled data by ethnicity and source of controls revealed that the association between the T allele and an increased risk of breast cancer was more pronounced among Asians (TT vs. CC: OR?=?1.26, 95 % CI?=?1.02–1.57, P?=?0.720; TT vs. TC?+?CC: OR?=?1.31, 95 % CI?=?1.07–1.61, P?=?0.708) and hospital-based studies (TT vs. CC: OR?=?1.25, 95 % CI?=?1.02–1.53, P?=?0.877; TT vs. TC?+?CC: OR?=?1.27, 95 % CI?=?1.05–1.53, P?=?0.540). No notable heterogeneity was indicated across studies. Our meta-analysis demonstrates that CD243 gene polymorphism may act as a predisposition factor for breast cancer, particularly in Asian populations.     

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.     

Common variant on MDM2 contributes to endometrial cancer susceptibility: evidence based on 7 studies

Due to its important biological function as a key negative regulator of p53, the mouse double minute 2 homologue (MDM2) gene has been extensively studied. A functional variant in the MDM2 gene promoter, single-nucleotide polymorphism 309 (SNP309) T > G (rs2279744), has been reported to cause an increase in MDM2 protein levels and impairment of p53 tumor suppressor activity, which may be associated with the development of cancer. A number of studies were performed to investigate the relationship between this SNP and endometrial cancer. But, the results remain controversial. Thus, we performed a comprehensive meta-analysis to derive a more precise estimation of this susceptibility. There were seven eligible articles with a total of 1,278 patients and 2,189 controls included in the meta-analysis. In the present study, we found significant associations under the allele contrast and recessive model. The G allele was associated with elevated risk for endometrial cancer [allele contrast OR?=?1.33, 95 % confidence interval (CI)?=?1.12–1.58, P(Z)?=?0.0009, P(Q)?=?0.02)], while the homozygous GG genotype may also increase the risk of endometrial cancer [OR?=?1.88, 95 % CI?=?1.40–2.52, P(Z)?P(Q)?=?0.02]. In the subgroup analysis by ethnicity, we found similar significant results for both Caucasians [allele contrast OR?=?1.41, 95 % CI?=?1.04–1.92, P(Z)?=?0.03, P(Q)?=?0.001; recessive model OR?=?1.89, 95 % CI?=?1.10–3.23, P(Z)?=?0.02, P(Q)?=?0.002] and Asians [allele contrast OR?=?1.24, 95 % CI?=?1.01–1.53, P(Z)?=?0.04, P(Q)?=?0.86; recessive model OR?=?1.75, 95 % CI?=?1.24–2.45, P(Z)?=?0.001, P(Q)?=?0.75]. Overall, the meta-analysis demonstrated that the MDM2 SNP309 polymorphism may be associated with increased risk of endometrial cancer.     

Association between FAS A670G polymorphism and susceptibility to cervical cancer: evidence from a meta-analysis

Previous studies published to evaluate the association between FAS A670G polymorphism and susceptibility to cervical cancer provided conflicting findings. A meta-analysis of published case–control studies was performed to get a comprehensive evidence for the possible association. We searched in PubMed and Wanfang databases for eligible studies published before February 10, 2013. The odds ratio (OR) with 95 % confidence interval (95 % CI) was used to evaluate the association. Ten studies with a total of 4,904 participants were finally included into the meta-analysis. Overall, there was no obvious association between FAS A670G polymorphism and susceptibility to cervical cancer under all four genetic models (G versus A: OR?=?0.97, 95 % CI 0.84–1.11, P?=?0.64; GG versus AA: OR?=?0.92, 95 % CI 0.69–1.24, P?=?0.60; GG/AG versus AA: OR?=?0.99, 95 % CI 0.77–1.26, P?=?0.92; GG versus AA/AG: OR?=?0.92; 95 % CI 0.68–1.25, P?=?0.59). Subgroup analyses by ethnicity further showed that there was no association between FAS A670G polymorphism and susceptibility to cervical cancer in both Caucasians and Asians. There was no risk of publication bias. In summary, the meta-analysis suggests that there is no association between FAS A670G polymorphism and susceptibility to cervical cancer in both Caucasians and Asians.     

Meta-analysis of the relation between vitamin D receptor gene BsmI polymorphism and susceptibility to ovarian cancer

The role of vitamin D receptor (VDR) BsmI polymorphism in ovarian cancer development has been studied in various populations, but those results are discordant controversial and ambiguous. Thus, we performed a meta-analysis to assess the association between VDR BsmI polymorphism and susceptibility to ovarian cancer more precisely. Odds ratio (OR) and its 95 % confidence interval (95 % CI) were used for statistical analysis. Nine individual studies with a total 2,331 cases and 3,301 controls were included into this meta-analysis. There was no heterogeneity among those nine studies. Meta-analysis of total nine studies suggested that there was no association between VDR BsmI polymorphism and susceptibility to ovarian cancer (B vs. b, OR?=?1.02, 95 % CI?=?0.94–1.10, P?=?0.616, I ²?=?0 %; BB vs. bb, OR?=?1.02, 95 % CI?=?0.87–1.20, P?=?0.810, I ²?=?0 %; BB/Bb vs. bb, OR?=?1.05, 95 % CI?=?0.94–1.18, P?=?0.391, I ²?=?0 %; BB vs. bb/Bb, OR?=?0.99, 95 % CI?=?0.85–1.14, P?=?0.853, I ²?=?0 %). Meta-analysis of seven studies from Caucasians also showed that there was no association between VDR BsmI polymorphism and susceptibility to ovarian cancer. This meta-analysis suggests that there is no association between VDR BsmI polymorphism and susceptibility to ovarian cancer in Caucasians. Future studies from Asians or Africans are needed to further assess the above association.     

Association between FAS-1377 G/A polymorphism and susceptibility to gastric cancer: evidence from a meta-analysis

Previous studies published to evaluate the association between FAS-1377 G/A polymorphism and susceptibility to gastric cancer provided inconclusive outcomes. To derive a more precise estimation on this association, a meta-analysis of published case–control studies was performed. Eligible studies up to November 13, 2012 were identified from PubMed, Wanfang Medicine database, and Web of Science. Nine studies with a total of 2,086 cases and 2,701 controls were finally included into this meta-analysis. Overall, there was an obvious association between FAS-1377 G/A polymorphism and susceptibility to gastric cancer (for AA versus GG: odds ratio (OR)?=?1.38; 95 % confidence interval (CI) 1.00–1.91, P?=?0.05; for AA versus GA/GG: OR?=?1.28; 95 %CI 1.07–1.53, P?=?0.006). After excluding studies with low quality, there was no between-study heterogeneity, and there was still an obvious association between FAS-1377 G/A polymorphism and susceptibility to gastric cancer (for AA versus GG: OR?=?1.25; 95 %CI 1.02–1.52, P?=?0.03; for AA versus GA/GG: OR?=?1.27; 95 %CI 1.05–1.53, P?=?0.01). Subgroup analyses by ethnicity showed that the association above was still obvious in Asians, but the association was still unclear in Caucasians owing to the limited sample. In summary, this meta-analysis suggests that the FAS-1377 G/A polymorphism is associated with susceptibility to gastric cancer, especially in Asians. More studies from Caucasians are needed to provide further evidence for the possible association in Caucasians.     

Quantitative assessment of the association between XRCC3 C18607T polymorphism and glioma risk

XRCC3 has an important function in the DNA double-strand break, and XRCC3 C18607T polymorphism is a common polymorphism at exon 7 of the XRCC3 gene. Published data on the association between XRCC3 C18607T polymorphism and glioma risk were inconclusive. Electronic databases of PubMed, and Embase were searched for studies assessing the association between XRCC3 C18607T polymorphism and glioma risk. Pooled odds ratio (OR) and 95 % confidence interval (95 % CI) were calculated to estimate the association. Ten studies with five studies from Caucasians and five studies from Asians were included, including 9,369 subjects. Meta-analysis of total included studies showed that XRCC3 C18607T polymorphism was associated with increased risk of glioma (T vs. C: OR?=?1.14, 95 % CI 1.02–1.28, P?=?0.02; TT vs. CC: OR?=?1.37, 95 % CI 1.03–1.83, P?=?0.03; TT vs. CC/CT: OR?=?1.31, 95 % CI 1.00–1.71, P?=?0.05; TT/CT vs. CC: OR?=?1.12, 95 % CI 1.02–1.22, P?=?0.02). Meta-analysis of the five studies from Asians showed that XRCC3 C18607T polymorphism was associated with increased risk of glioma (T vs. C: OR?=?1.22, 95% CI 1.09–1.36, P?<?0.01; TT vs. CC: OR?=?1.89, 95 % CI 1.38–2.57, P?<?0.01; TT vs. CC/CT: OR?=?1.78, 95 % CI 1.31–2.40, P?<?0.01; TT/CT vs. CC: OR?=?1.19, 95 % CI 1.04–1.36, P?=?0.01). Meta-analysis of the five studies from Caucasians didn’t find the association. In conclusion, the finding from the meta-analysis provides strong evidence for the association between XRCC3 C18607T polymorphism and glioma risk.     

Genetic polymorphism of DNA methyltransferase 3B 149 C>T and risk of colorectal cancer: a meta-analysis

Numerous studies have investigated the risk of colorectal cancer (CRC) associated with the polymorphism of DNA methyltransferase 3B (DNMT3B) 149 C>T, but results have been inconsistent. We performed this meta-analysis to drive a more precise estimation of the association between this polymorphism and risk of CRC. A comprehensive search was conducted to identify all case–control studies of the ?149C>T polymorphism of DNMT3B and CRC risk. A total of seven eligible studies, including 2,666 cases and 4,022 controls, relating the DNMT3B polymorphism of ?149C>T to the risk of CRC were identified. It suggested no significant associations between ?149C>T polymorphism of DNMT3B gene and the risk of developing CRC in the recessive, dominant, and co-dominant models (for CC versus TT: OR?=?0.90, 95 % CI?=?0.90–1.25, P _{heterogeneity}?=?0.37; for recessive model: OR?=?0.54, 95 % CI?=?0.28–1.04, P _{heterogeneity}?=?0.00001; for dominant model: OR?=?1.07, 95% CI?=?0.93–1.23, P _{heterogeneity}?=?0.83; and for C allele versus T allele: OR?=?0.70, 95 % CI?=?0.43–1.13, P _{heterogeneity}?=?0.00001). In the subgroup analysis, there is no significant associations were also found in European populations (for CC versus TT: OR?=?1.09, 95 % CI?=?0.92–1.30, P _{heterogeneity}?=?0.88; for recessive model: OR?=?1.00, 95 % CI?=?0.88–1.13, P _{heterogeneity}?=?0.14; for dominant model: OR?=?1.50, 95 % CI?=?0.89–2.54, P _{heterogeneity}?=?0.00001; and for C allele versus T allele: OR?=?0.70, 95 % CI?=?0.38–1.28, P _{heterogeneity}?=?0.00001). In conclusion, no significant association was found between the ?149C>T polymorphisms in DNMT3B and CRC susceptibility.     

Quantitative assessment of the association between MTHFR rs1801131 polymorphism and risk of liver cancer

Methylenetetrahydrofolate reductase (MTHFR) is one of the most important enzymes for folate metabolism which plays a key role in cell metabolism. MTHFR rs1801131 (A1298C) polymorphism can decrease in vitro MTHFR enzyme activity and has been hypothesized to be associated with liver cancer risk. This study aimed to quantify the strength of the association between MTHFR rs1801131 polymorphism and liver cancer risk by performing a meta-analysis. We searched the PubMed and Wanfang databases for studies relating on the association between MTHFR rs1801131 polymorphism and risk of liver cancer. Seven studies with 2,030 cases of liver cancer and 3,096 controls were finally included into the meta-analysis. Meta-analysis of a total of seven studies showed that the homozygote genotype CC of MTHFR rs1801131 polymorphism was significantly associated with decreased risk of liver cancer (for CC versus AA: odds ratio (OR)?=?0.65, 95 % confidence interval (CI) 0.47–0.89, P?=?0.007; for CC versus AA?+?AC: OR?=?0.65, 95 % CI 0.48–0.89, P?=?0.006). Subgroup by race showed that the homozygote genotype CC of MTHFR rs1801131 polymorphism was significantly associated with decreased risk of liver cancer in Asians (CC versus AA: OR?=?0.64, 95 % CI 0.46–0.90, P?=?0.010; for CC versus AA?+ AC: OR?=?0.63, 95 % CI 0.45–0.88, P?=?0.007). However, the association in Caucasians was still unclear owing to the limited data available now. Thus, Asian individuals with the homozygote genotype CC of MTHFR rs1801131 polymorphism are significantly associated with decreased risk of liver cancer. The association in Caucasians needs further studies.     

Vitamin D receptor gene ApaI polymorphism and breast cancer susceptibility: a meta-analysis

Vitamin D receptor (VDR) principally mediates the anticancer activities of vitamin D. Many studies investigated the association between VDR gene ApaI polymorphism and breast cancer, but the results were inconclusive. We performed this meta-analysis to evaluate the association between VDR gene ApaI polymorphism and breast cancer. Twelve studies with a total of 8,254 subjects were identified from PubMed and Wanfang databases. The pooled odds ratio (OR) and confidence intervals (95 % CI) were used to assess the association. The meta-analysis indicated that VDR gene ApaI polymorphism was not associated with risk of breast cancer (a vs. A: OR?=?0.97, 95 % CI 0.91–1.04, P?=?0.378; aa vs. AA: OR?=?0.97, 95 % CI 0.85–1.10, P?=?0.618; aa vs. AA + Aa: OR?=?1.00, 95 % CI 0.89–1.12, P?=?0.972; aa + Aa vs. AA: OR?=?0.95, 95 % CI 0.82–1.11, P?=?0.550). Subgroup analysis by ethnicity further showed that VDR gene ApaI polymorphism was not associated with risk of breast cancer in both Asians and Caucasians. These data from the meta-analysis indicate that VDR gene ApaI polymorphism is not associated with breast cancer susceptibility.     

Association between the GSTP1 Ile105Val polymorphism and prostate cancer risk: a systematic review and meta-analysis

Many studies have reported the role of glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism with prostate cancer (PCa) risk. However, these studies have yielded conflicting results. Hence, we performed this meta-analysis to investigate the association between GSTP1 Ile105Val polymorphism and PCa in different inheritance models. A total of 13 eligible studies were pooled into this meta-analysis. There was significant association between the GSTP1 Ile158Val variant genotypes and PCa for Ile/Ile vs Val/Val comparison [odds ratio (OR)?=?0.705; I ²?=?63.7 %; 95 % confidence interval (95 % CI)?=?0.508–0.977], Ile/Val vs Val/Val comparison (OR?=?0.736; I ²?=?8.0 %; 95 % CI?=?0.613–0.883), and dominant model (OR?=?0.712; I ²?=?45.5 %; 95 % CI?=?0.555–0.913). However, no associations were detected for other genetic models. In the stratified analysis by ethnicity, significant associations between GSTP1 Ile105Val polymorphism and PCa risk were also found among Caucasians (Ile/Ile vs Val/Val comparison OR?=?0.818, I ²?=?0.0 %, 95 % CI?=?0.681–0.982; Ile/Val vs Val/Val comparison OR?=?0.779, I ²?=?0.0 %, 95 % CI?=?0.651–0.933; and dominant model OR?=?0.794, I ²?=?0.0 %, 95 % CI?=?0.670–0.941), while there were no associations found for other genetic models. However, no associations were found in Asians and African-Americans for all genetic models when stratified by ethnicity. In conclusion, our meta-analysis indicates that GSTP1 Ile105Val polymorphisms contributed to the PCa susceptibility. However, a study with the larger sample size is needed to further evaluate gene–environment interaction on GSTP1 Ile105Val polymorphisms and PCa risk.     

Lack of association between MTHFD1 G401A polymorphism and ovarian cancer susceptibility

Published studies on the association between methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) G401A polymorphism and ovarian cancer risk have yielded conflicting results. In order to derive a more precise estimation of the relationship between G401A polymorphism and ovarian cancer risk, the present meta-analysis was performed. All eligible studies on G401A polymorphism and ovarian cancer risk were collected from the PubMed and the Cochrane Library. Statistical analyses were performed by Review Manage 5.0 and Stata 11.0. Our analysis suggested that G401A polymorphism was not associated with ovarian cancer risk when using additive (odds ratio (OR)?=?1.72, 95 % confidence interval (CI)?=?1.34–2.20, P?<?0.0001), recessive (OR?=?1.46, 95 % CI?=?1.21–1.77, P?<?0.0001), dominant (OR?=?1.36, 95 % CI?=?1.10–1.69, P?=?0.004), and allelic models (OR?=?1.30, 95 % CI?=?1.15–1.47, P?<?0.0001) to analyze the data. This meta-analysis suggests that G401A polymorphism might not be a risk factor for ovarian cancer risk. However, further well-designed studies are required to confirm our findings.     

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 Cyclin D1 polymorphism and oral cancer susceptibility: a meta-analysis

Data from several case–control studies on the relation between the Cyclin D1 (CCND1) G870A polymorphism and oral cancer susceptibility implicated conflicting conclusions. Thus, a meta-analysis was performed to derive a more precise evaluation of the association. We searched PubMed and Embase for related studies that had been published in English and eight available studies were finally included in the meta-analysis. Odd ratios (ORs) and 95 % confidence intervals (CIs) were calculated for each study. Our meta-analysis suggested that CCND1 G870A polymorphism was not associated with oral cancer risk (OR _{AA vs. GG}?=?1.08, 95 % CI?=?0.90–1.30, P _{heterogeneity}?=?0.175; OR _{AA + GA vs. GG}?=?1.02, 95 % CI?=?0.91–1.14, P _{heterogeneity}?=?0.781; OR _{AA vs. GA + GG}?=?1.16, 95 % CI?=?0.98–1.36, P _{heterogeneity}?=?0.107; OR _{A vs. G}?=?1.05 95 % CI?=?0.96–1.15, P _{heterogeneity}?=?0.211; OR _{GA vs. GG}?=?0.94, 95 % CI?=?0.82–1.08, P _{heterogeneity}?=?0.935). However, in the subgroup analysis by ethnicity, possible significance among Asian groups was indicated in two genetic models (OR _{AA vs. GA + GG}?=?1.27, 95 % CI?=?1.05–1.54, P _{heterogeneity}?=?0.572; OR _{allele A vs. allele G}?=?1.11, 95 % CI?=?1.00–1.24, P _{heterogeneity}?=?0.211). Taken together, the meta-analysis revealed that CCND1 G870A polymorphism might be correlated with the susceptibility of oral cancer in Asians.