This meta-analysis of published cohort studies was conducted to evaluate whether promoter methylation of the RASSF1A gene contributes to colorectal cancer (CRC) susceptibility. A range of electronic databases were searched without language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude risk differences (RD) with their 95% confidence intervals (95%CI) were calculated. In this meta-analysis, 11 clinical cohort studies with a total of 630 CRC patients were included. The pooled results revealed that the frequency of RASSF1A gene methylation in cancer tissues was significantly higher than that in benign, adjacent, and normal tissues (cancer tissues vs. benign tissues: RD = 0.25, 95%CI = 0.13-0.38, P < 0.001; cancer tissues vs. adjacent tissues: RD = 0.32, 95%CI: 0.20-0.45, P < 0.001; cancer tissues vs. normal tissues: RD = 0.38, 95%CI: 0.26-0.50, P < 0.001; respectively). Subgroup analysis by ethnicity demonstrated that RASSF1A promoter methylation also exhibited a higher frequency in cancer tissues among both Asians and Caucasians (all P < 0.05). Our meta-analysis has shown positive correlations between RASSF1A promoter methylation and CRC susceptibility. Thus, detection of RASSF1A promoter methylation may be utilized as a valuable diagnostic marker for CRC.

To discover significant differentially expressed genes (DEGs) in clear cell renal cell carcinoma (ccRCC) that might be unidentified by single microarray analysis.

Several studies have assessed the association of CD95L polymorphism with cervical cancer risk, but the data lack the power to provide compelling evidence. In this study, we aimed to clarify the association through a meta-analysis. A comprehensive search was conducted in PubMed, Embase, and Web of Science. The fixed-effects model was used to calculate odds ratio (OR) with 95 % confidence intervals (CIs). A total of five papers with six case-control studies were derived and finally included in this meta-analysis. The overall estimate did not reveal any significant association between CD95L -844C/T polymorphism and cervical cancer risk. Subgroup analysis in Asian population indicated nonsignificant nevertheless potentially increased risk in CC genotype carriers in comparison with the carriers of CT+TT genotypes (ORCC vs. CT+TT=1.16, 95 % CI=0.99-1.36, P for heterogeneity=0.231). Based on current epidemiological studies, this meta-analysis suggests that CD95L polymorphism may not be a risk factor contributing to cervical cancer development.

Several genome-wide association studies on lung cancer (LC) have reported similar findings of a new susceptibility locus, 5p15. After that, a number of studies reported that the rs2736100, rs401681, rs402710, and rs31489 polymorphisms at chromosome 5p15 have been implicated in LC risk. However, the studies have yielded contradictory results. To derive a more precise estimation of the relationship, we performed this meta-analysis. Databases including MEDLINE, PubMed, EMBASE, ISI Web of Science, and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95 % confidence intervals (CIs) were used to assess the strength of association. The random effect model was applied, addressing heterogeneity and publication bias. A total of 31 articles involving 72,401 cases and 141,258 controls were included. Overall, significantly elevated LC risk was associated with rs2736100, rs401681, rs402710, and rs31489 polymorphisms when all studies were pooled into the meta-analysis. In the subgroup analysis by ethnicity, sample size, histology, sex, and smoking behavior, significantly increased risks were also detected for these polymorphisms. Our findings demonstrated that these common variations at 5p15 are a risk factor associated with increased LC susceptibility. However, these associations vary between different ethnicity.

Recent evidence suggests that genetic variations in the insulin-like growth factor (IGF)-IGF receptor (IGFR)-IGF binding proteins (IGFBP) axis may impact an individual's susceptibility to lung and esophageal cancer, but individually published results are inconclusive. Our meta-analysis aimed at providing a more precise estimation of these associations. An extensive literature search was conducted for appropriate articles published before May 15th, 2013. This meta-analysis was performed using the STATA 12.0 software. The crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for each study and then pooled using a random effect model. Twelve case-control studies were included with a total of 2686 lung cancer patients, 771 esophageal cancer patients, and 5918 healthy controls. Our meta-analysis indicated that genetic variations in the IGF-IGFR-IGFBP axis may be associated with increased risk of lung and esophageal cancer, especially among Asian populations. Further subgroup analysis by gene type indicated that common polymorphisms in the IGF1/2, IGF-1R, and IGFBP-3/5 genes may be the main determinants for lung cancer risk, while IGF-1, IGF-1R, and IGFBP-1 genetic polymorphisms may increase the risk of esophageal cancer. The current meta-analysis suggests that genetic variations in the IGF-IGFR-IGFBP axis confer susceptibility to lung and esophageal cancer, especially among Asian populations. Common polymorphisms in the IGF-IGFR-IGFBP axis may serve as useful biomarkers for predicting the risk of lung and esophageal cancer.

Several previous studies have investigated whether the -160C/A epithelial cadherin promoter polymorphism confers an increased risk of diffuse gastric cancer (DGC), but conflicting results have been reported. To explore further the association of this polymorphism with DGC susceptibility, we performed an extensive search of relevant studies and conducted a meta-analysis to obtain a more precise estimate. We conducted a systematic literature search using the databases EMBASE, PubMed, and Web of Knowledge for reports published before August 2012 that met certain criteria. Information was carefully and independently extracted from all eligible publications by 2 of the authors. Twelve distinct data sets from 10 case-control studies were analyzed. They included 1115 cases of DGC and 2965 controls. Although none of the genotypes was associated with DGC risk, a slight trend of increased risk was found among A allele carriers [odds ratio (OR) = 1.237, 95% confidence interval (95%CI), 0.940-1.627], CA heterozygotes (OR = 1.229, 95%CI = 0.938-1.610), and AA homozygotes (OR = 1.146, 95%CI = 0.684-1.918). However, when the cases were stratified by ethnicity, a diverging trend occurred in AA homozygotes between the Asian group (OR = 0.710, 95%CI = 0.328-1.536) and its Caucasian counterpart (OR = 1.434, 95%CI = 0.657-3.131). Taken together, the summarized analyses of these case-control studies demonstrated that the -160A of the epithelial cadherin gene exhibited no significant association with susceptibility for DGC; however, the results suggested that it is a potential genetic risk factor in both Asians and Caucasians. Additional large-scale, well-designed studies are necessary to confirm whether AA homozygosity is a protective factor in Asians.

Microsomal epoxide hydrolase 1 (EPHX1) is an important biological phase II metabolic enzyme that is extensively involved in the metabolism of diverse environmental carcinogens such as polycyclic aromatic hydrocarbons and heterocyclic amines. Many articles have reported the association between EPHX1 (Tyr113His and His139Arg) polymorphisms and esophageal cancer risk, but the results are controversial. This study aimed to identify the association between EPHX1 (Tyr113His and His139Arg) polymorphisms and esophageal cancer risk by meta-analysis. The odds ratio (OR) with 95% confidence interval (95%CI) was used to evaluate the strength of the associations. Heterogeneity was estimated by the chi-square-based Q-statistic test and the P value. Meanwhile, the random-effect or fixed-effect model was used according to the between-study heterogeneity. Begg's funnel plot and the Egger test were performed to assess the publication bias of articles. Finally, 8 case-control studies involving 1158 cases and 1868 controls for the Tyr113His polymorphism and 7 case-control studies involving 901 cases and 1615 controls for the His139Arg polymorphism were included in this meta-analysis. Meta-analysis showed that the Tyr113His polymorphism was a stronger power trend towards risk for esophageal cancer using a recessive model (CC versus CT+TT, OR = 1.204, 95%CI = 1.001-1.450, P = 0.049). However, no significant associated risk was found between the His139Arg polymorphism and esophageal cancer. These findings suggest that the Tyr113His polymorphism might be a stronger power trend towards risk for esophageal cancer. However, no evidence was found for the association between the EPHX1 His139Arg polymorphism and esophageal cancer risk.

This meta-analysis was performed to evaluate the relationships between genetic polymorphisms in the TCF7L2 gene and polycystic ovary syndrome (PCOS) risk.

This meta-analysis aims to evaluate the effects of common polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene on the toxicity and clinical responses of irinotecan-based chemotherapy in patients with colorectal cancer (CRC).

Many existing studies have demonstrated that pituitary tumor transforming gene (PTTG) expression may contribute to the development of pituitary adenomas (PAs), but individually published studies showed inconclusive results. This meta-analysis aimed to derive a more precise estimation of the relationships of PTTG expression with tumor invasiveness and microvessel density of pituitary adenomas.

Many studies have shown that the +252A/G polymorphism in the lymphotoxin-α gene is implicated in susceptibility to non-Hodgkin lymphoma but with considerable variance of results. This study aimed to clarify the overall association between the +252A/G polymorphism in the lymphotoxin-α gene and non-Hodgkin lymphoma (NHL) risk by performing a meta-analysis.

Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases with an uncertain pathology and the most frequent incretory disorder in women of reproductive age, often leading to female infertility. Evidence has shown that genetic factors may contribute to the etiology of PCOS. Contradictory results have been reported concerning the association between PCOS and the CYP11A1 gene promoter -528 bp pentanucleotide (tttta)n repeat polymorphism. In order to get an overall understanding of the association between the CYP11A1 gene promoter -528 bp pentanucleotide (tttta)n repeat polymorphism and PCOS, case-control studies regarding this association were extracted from MEDLINE, Ovid EMBASE and PubMed and pooled for meta-analysis. In dichotomous allelic analyses with 1,236 PCOS patients and 1,306 control subjects, the odds ratios (ORs) were very close to 1. In dichotomous genotypic analyses with 1,063 PCOS patients and 1,176 control subjects, the (tttta)4 genotype may increase the risk of PCOS in a recessive model with OR 1.44, 95% confidence interval (CI) 1.12-1.85, and the (tttta)6 genotype may decrease the risk of PCOS in a dominant model with OR 0.76, 95% CI 0.61-0.93. In continuous analyses with 1,085 PCOS patients and 1,216 control subjects, the Mean Difference (MD) was -0.07 with a 95% CI -0.18 to 0.05, showing no difference between PCOS and control groups. No publication bias was found in either dichotomous or continuous analyses. Taken together, there may be an association between CYP11A1 promoter pentanucleotide repeat polymorphism and PCOS. Further research is needed to strictly confirm our findings.

This meta-analysis was performed to evaluate the relationships between promoter DNA methylation in tumor suppressor gene p16 and gastric carcinogenesis. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated. Forty-seven clinical cohort studies that met all inclusion criteria were included in this meta-analysis. A total of 2,813 gastric cancer (GC) patients were assessed. Our meta-analysis results revealed that the frequencies of p16 promoter methylation in the GC tissues were higher than those of normal and adjacent tissues (Normal: OR = 23.04, 95% CI = 13.55-39.15, P < 0.001; Adjacent: OR = 4.42, 95% CI = 1.66-11.76, P = 0.003; respectively). Furthermore, we observed significant associations of p16 promoter methylation with TNM stage, histologic grade, invasive grade, lymph node metastasis of GC (TNM stage: OR = 3.60, 95% CI: 2.17-5.98, P < 0.001; Histologic grade: OR = 2.63, 95% CI: 1.55-4.45, P < 0.001; Invasive grade: OR = 3.44, 95% CI: 1.68-7.06, P = 0.001; Lymph node metastasis: OR = 2.68, 95% CI: 1.66-4.32, P < 0.001; respectively). However, there were no correlations of p16 promoter methylation with the TNM stage and Helicobacter pylori (HP) infection of GC (Tumor size: OR = 0.76, 95% CI: 0.14-4.07, P = 0.746; HP infection: OR = 1.31, 95% CI: 0.75-2.27, P = 0.342; respectively). Our findings provide empirical evidence that p16 promoter methylation may play an important role in gastric carcinogenesis. Thus, p16 promoter methylation may be a promising potential biomarker for the early diagnosis of GC.

Vitamin D receptor (VDR) gene polymorphisms have previously been associated with susceptibility to renal cell carcinoma, although the findings are inconsistent. This study therefore evaluated the association of three single nucleotide polymorphisms (SNPs) in VDR (FokI, BsmI, and TaqI) with the risk of renal cell carcinoma in five previous studies of a total of 1,510 cases and 2,101 controls identified from PubMed, Web of Science, Embase, and Wanfang databases. Pooled odds ratios (ORs) and corresponding 95 % confidence intervals (CIs) were calculated, and stratified analysis by ethnicity was conducted for further estimation. All statistical analyses were conducted using STATA software. Obvious heterogeneity was noted among the five studies. The VDR BsmI polymorphism was not found to be associated with renal cell carcinoma risk, although subgroup analysis revealed a significant association with renal cell carcinoma risk in Asians (b vs B OR=1.479, 95 % CI=1.171-1.869, P OR=0.001 and bb vs BB OR=2.608, 95 % CI=1.529-4.449, P OR=0.001). No significant association was found between renal cell carcinoma risk and either FokI or TaqI polymorphisms in different models and populations. Further large-scale studies are required to confirm these conclusions.

Although many epidemiologic studies investigated the methylenetetrahydrofolate reductase (MTHFR) polymorphisms and their associations with esophageal cancer, definite conclusions could not be drawn. To clarify the effects of MTHFR polymorphisms on the risk of esophageal cancer, a meta-analysis was here performed in Chinese populations. A total of 16 studies including 3,040 cases and 4,127 controls were involved in this meta- analysis. Overall, significant associations were found between the MTHFR C677T polymorphism and esophageal cancer risk when all studies in Chinese populations were pooled into the meta-analysis (T vs. C, OR = 1.19, 95% CI = 1.06-1.34; TT vs. CC, OR = 1.35, 95% CI = 1.07-1.70; TT+ CT vs. CC, OR = 1.29, 95% CI = 1.08-1.54; TT vs. CC + CT, OR = 1.19, 95% CI = 1.03-1.37). In subgroup analyses stratified by ethnicity and source of controls, the same results were found in Kazakh (TT vs. CC, OR = 1.38, 95% CI = 1.02-1.87; TT + CT vs. CC, OR = 1.50, 95% CI = 1.03-2.18), in not stated populations (T vs. C, OR = 1.24, 95% CI = 1.08-1.42; TT vs. CC, OR = 1.47, 95% CI = 1.10-1.96; TT + CT vs. CC, OR = 1.30, 95% CI = 1.05-1.60; TT vs. CC + CT, OR = 1.32, 95% CI = 1.12-1.56), and in hospital-based studies (T vs. C, OR = 1.34, 95% CI = 1.19-1.51; TT vs. CC, OR = 1.81, 95% CI = 1.37-2.39; TT + CT vs. CC, OR = 1.51, 95% CI = 1.26-1.83; and TT vs. CC + CT, OR = 1.39, 95% CI = 1.13-1.70). In conclusion, this meta-analysis provides evidence that the MTHFR C677T polymorphism contributes to esophageal cancer development in Chinese populations.

Matrix metalloproteinases (MMPs) play important roles in pathogenesis and development of cancer. Recently, many studies have show associations between polymorphisms in the promoter regions of MMPs and risk of gastric cancer. The present meta-analysis was conducted in order to investigate the potential association between four polymorphisms in the MMP gene and gastric cancer risk.

The TP53BP1 gene may be involved in the development of cancer through disrupting DNA repair. However, studies investigating the relationship between TP53BP1 Glu353Asp (rs560191) polymorphism and cancer yielded contradictory and inconclusive outcomes. In order to realize these ambiguous findings, a meta-analysis was performed to assess the association between the TP53BP1 Glu353Asp (rs560191) polymorphism and susceptibility to cancer.

Genetic polymorphisms of RAD51 135 G>C and XRCC2 G>A (rs3218536) have been reported to change the risk of ovarian cancer, but the results are controversial. To get a more precise result, a meta-analysis was performed. A comprehensive literature search in PubMed, Excerpta Medica Database, and China National Knowledge Infrastructure was carried out to get case-control studies published up to November 2013. The pooled odds ratio (OR) and its corresponding 95 % confidence interval (CI) were conducted to estimate the effect of RAD51 135 G>C and XRCC2 G>A (rs3218536) polymorphisms on ovarian cancer risk. A total of 13 independent case-control studies with 5,927 cases and 10,303 controls were included in this meta-analysis. There was no significant association between RAD51 135 G>C polymorphism and risk of ovarian cancer. However, the result of total studies indicated the XRCC2 G>A (rs3218536) polymorphism could reduce the risk of ovarian cancer (heterozygote model AG vs. GG: OR=0.877, 95 % CI=0.770-0.999, P=0.048; dominant model AA/AG vs. GG: OR=0.864, 95 % CI=0.763-0.979, P=0.022). The result was still significant after Hardy-Weinberg equilibrium-violating studies were excluded (allele contrast A vs. G: OR=0.836, 95 % CI=0.74-0.943, P=0.004; homozygote model AA vs. GG: OR=0.562, 95 % CI=0.317-0.994, P=0.048; heterozygote model AG vs. GG: OR=0.859, 95 % CI=0.753-0.98, P=0.023; dominant model AA/AG vs. GG: OR=0.842, 95 % CI=0.74-0.958, P=0.009). In the stratified analysis by ethnicity, significantly reduced risk was observed among Caucasians in dominant model (AA/AG vs. GG: OR=0.867, 95 % CI=0.764-0.984, P=0.027). No significant association was found between the RAD51 135G>C polymorphism and the risk of ovarian cancer. Interestingly, XRCC2 G>A (rs3218536) polymorphism might reduce the risk of ovarian cancer. Larger-scale and well-designed studies are needed to further clarify the association.

Risk of non-Hodgkin lymphoma (NHL) is higher among individuals with a family history or a prior diagnosis of other cancers. Genome-wide association studies (GWAS) have suggested that some genetic susceptibility variants are associated with multiple complex traits (pleiotropy).

The association between Aurora-A V57I (rs1047972, G>A) polymorphism and cancer susceptibility has been widely studied. However, the results are inconsistent.