Previous studies accessing the association of CYP2C19 with outcomes of patients using tamoxifen for breast cancer have yielded conflicting results. The aim of this meta-analysis is to obtain a more precise estimate of effects of CYP2C19 polymorphisms and to clarify their effects on survival of the breast cancer patients using tamoxifen.

A meta-analysis incorporating 34 case-control studies from 19 articles involving 12,197 cases and 13,488 controls was conducted to assess the effects of three genetic variants of Toll-like receptor 9 (TLR9): rs187084, rs352140, and rs5743836. Studies on associations between TLR9 polymorphisms and cancer risk were systematically searched in electronic databases. The reported odds ratios (OR) and 95% confidence intervals (CI) were pooled to assess the strength of any associations. The results showed that the rs187084 polymorphism was significantly associated with an increased risk of cancer (CC vs TC+TT: OR=1.14, 95% CI=1.02-1.28), specifically cervical cancer (C vs T: OR=1.19, 95% CI=1.05-1.34; TC vs TT: OR=1.32, 95% CI=1.10-1.58; CC vs TT: OR=1.31, 95% CI= 1.03-1.68; CC+TC vs TT: OR=1.32, 95% CI=1.11-1.56), and that this association was significantly positive in Caucasians (CC vs. TC+TT: OR=1.18, 95% CI=1.01-1.38). The rs352140 polymorphism had a protective effect on breast cancer (GA vs GG: OR=0.77, 95% CI=0.66-0.89), whereas the rs5743836 polymorphism was likely protective for digestive system cancers (CC+TC vs TT: OR=0.81, 95% CI=0.66-0.98). In conclusion, our results suggest that the rs187084 polymorphism may be associated with an elevated cancer risk, whereas polymorphisms of rs352140 and rs5743836 may play protective roles in the development of breast and digestive system cancers, respectively. From the results of this meta-analysis further large-scale case-control studies are warranted to verify associations between TLR9 polymorphisms and cancer.

Previous studies investigating the association between 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and colon cancer risk have generated conflicting results. The aim of our meta-analysis was to clarify the precise association. A systematic literature search was conducted to identify all relevant studies. Pooled odds ratio (ORs) with 95% confidence interval (CI) were used to estimate the strength of the association. In this meta-analysis, a total of 13 articles, involving 5,386 cases and 8,017 controls met the inclusion criteria. Overall, a significant association was found between colon cancer risk and the MTHFR C667 polymorphism (TT vs CC+CT: OR=0.79; 95%CI=0.65-0.96; p=0.017). Stratification by ethnicity revealed that MTHFRC667 was associated with colon cancer risk in the non-Asian group (TT vs CC+CT:OR=0.77, 95%CI=0.68-0.89, p=0.000; TT vs CC: OR=0.84, 95%CI=0.73-0.97, p=0.016). Stratification by source of control indicated that MTHFR C667 also correlated with colon cancer risk in the population-based subgroup (TT vs CC: OR=0.85, 95%CI=0.74-0.97, p=0.017; TT vs CC+CT: OR=0.78, 95%CI=0.68-0.89, p=0.000) and hospital-based subgroup (TT vs CC+CT: OR=0.65, 95%CI=0.49-0.86, p=0.003). However, risk was significantly increased for MTHFR A1298C polymorphisms and colon cancer risk in hospital-based studies (C vs A: OR=1.52, 95%CI=1.26-1.83, p=0.000; CC+AC vs AA: OR=1.93, 95%CI=1.47-2.49, p=0.000) but reduced in population-based studies (CC vs AA: OR=0.83, 95%CI=0.70-0.99, p=0.042). In conclusion, the results of our meta-analysis suggest that the MTHFR C667 polymorphism is associated with reduced colon cancer risk, especially for non-Asian populations.

To investigate the association of IL-17F rs763780T>C with cancer risk.

A common genetic variant rs3757318, located in intron of C6orf97, was firstly identified to be associated with breast cancer (BC) risk by a genome-wide association (GWA) study. However, subsequent validation studies with different ethnicities have yielded conflicting results.

The morbidity and mortality of cancer increase remarkably every year. It's a heavy burden for family and society. The detection of prognostic biomarkers can help to improve the theraputic effect and prolong the lifetime of patients. microRNAs have an influential role in cancer prognosis. The results of articles discussing the relationship between microRNA polymorphisms and cancer prognosis are inconsistent.

Angiotensin I-converting enzyme (ACE) gene plays an important role in the pathogenesis of cancers. The association between ACE insertion/deletion (I/D) polymorphism and the risk of various cancers has been studied. However, the results of these studies remain conflicting. Therefore, we performed a meta-analysis to evaluate the association between ACE I/D polymorphism and the risk of cancers.

Hypoxia-inducible factor-1 alpha (HIF-1α) P582S polymorphism has been reported to increase transactivation capacity of HIF-1α, which is prone to tumorigenesis. Several published case-control studies on the association between P582S polymorphism and cervical cancer have shown mixed results. In this study, we chose to perform a meta-analysis to assess the association.

Recent studies have highlighted the role of microRNA-21 (miR-21) as a prognostic biomarker of breast cancer. However, controversy still remains. The present study aimed to summarize available evidences and obtain a more precise estimation of a prognostic role of miR-21 in breast cancer patients. All eligible studies were searched from PubMed and EMBASE through multiple search strategies. Data were extracted from studies comparing survival in breast cancer patients having higher miR-21 expression with those having lower expression. A meta-analysis was performed to clarify prognostic role of miR-21 in patients with breast cancer. Subgroup analysis was also performed according to patients' ethnicity. A total of 6 eligible articles comprising 951 cases were selected for this meta-analysis. The combined hazard ratios (HRs) and 95% confidence intervals (95% CIs) for overall survival (OS) were 2.11 (1.09-4.08) and for disease free survival (DFS) was 1.6 (1.30-1.96). Subgroup analysis indicated high miR-21 expression was significantly associated with worse OS in Asian patients (HR = 4.39, 95% CI: 2.47-7.80) but not in non-Asian patients (HR = 1.18, 95% CI: 0.81-1.70). Sensitivity analysis revealed results of this meta-analysis were robust. Odds ratios (ORs) showed that miR-21 expression was closely associated with estrogen receptor (ER), progesterone receptor (PR), lymph node metastasis, histological grade, Her2/neu. The pooled ORs and 95% CIs were 0.53 (0.35-0.80), 0.49 (0.32-0.74), 2.32 (1.54-3.50), 2.44 (1.58-3.75), 4.29 (2.34-7.85), respectively. Our results indicated that elevated miR-21 expression could potentially predict poor survival in patients with breast cancer.

The previous, published data on the association between CYP2E1 RsaI (rs2031920), DraI (rs6413432) polymorphisms and lung cancer risk remained controversial. Hence, we performed a meta-analysis to investigate the association between lung cancer and CYP2E1 RsaI (5,074 cases and 6,828 controls from 34 studies), and CYP2E1 DraI (2,093 cases and 2,508 controls from 16 studies) in different inheritance models. Overall, significantly decreased lung cancer risk was observed (dominant model: odds ratio (OR) 0.80, 95 % confidence interval (95 % CI) 0.71-0.90; heterozygote model: OR 0.80, 95 % CI 0.70-0.90; additive model: OR 0.82, 95 % CI 0.72-0.94) when all the eligible studies were pooled into the meta-analysis of CYP2E1 RsaI polymorphism. In further stratified and sensitivity analyses, significantly decreased lung cancer risk was found among Asians (dominant model: OR 0.81, 95 % CI 0.71-0.93; heterozygous model: OR 0.81, 95 % CI 0.69-0.95), population-based studies (dominant model: OR 0.69, 95 % CI 0.54-0.88; recessive model: OR 0.39, 95 % CI 0.16-0.91; additive model: OR 0.67, 95 % CI 0.53-0.84; homozygous model: OR 0.34, 95 % CI 0.14-0.80; heterozygous model: OR 0.70, 95 % CI 0.54-0.91), hospital-based studies (dominant model: OR 0.80, 95 % CI 0.69-0.93; additive model: OR 0.84, 95 % CI 0.70-1.00; heterozygous model: OR 0.80, 95 % CI 0.68-0.95), lung AC (heterozygous model: OR 0.84, 95 % CI 0.71-1.00), smokers (dominant model: OR 0.72, 95 % CI 0.55-0.94), and non-smokers (dominant model: OR 0.74, 95 % CI 0.61-0.91). There was no significant association between CYP2E1 DraI polymorphism and the risk of lung cancer when all the eligible studies were pooled into the meta-analysis. However, in further stratified and sensitivity analyses, significant association was observed among smokers (dominant model: OR 0.49, 95 % CI 0.35-0.69). In summary, this meta-analysis indicates that CYP2E1 RsaI polymorphism is associated with lung cancer risk among Asians, CYP2E1 RsaI polymorphism may be associated with lung adenocarcinoma risk, and CYP2E1 RsaI and DraI polymorphisms may be associated with decreased lung cancer risk in smokers.

Various studies have reported that IKZF1 deletion (IKZF1-d) is a poor prognostic factor for acute lymphoblastic leukemia (ALL) patients, however they do not agree on the level of significance for this deletion.

+936C>T polymorphism of vascular endothelial growth factor (VEGF) is one of the most investigated polymorphisms, it has been suggested that it plays a vital role in tumorigenesis. Intensive studies centering on the association between VEGF +936C>T polymorphism and lung cancer risk or lung cancer patients' overall survival were conducted in recent years, but with inconclusive and ambiguous results.

Inflammation has been recognized as an important contributing factor in the development and progression of lung cancer. However, the relationship between the magnitude of inflammation and prognosis in patients with lung cancer remains unclear. This meta-analysis aimed to investigate the association between levels of circulating inflammatory factors and clinical survival in patients with non-small cell lung cancer(NSCLC).

The purpose of this study is to investigate the associations of the x-ray repair cross-complementing 1 gene (XRCC1) single nucleotide polymorphisms (SNPs) Arg194Trp, Arg280His, and Arg399Gln with gastric cancer risk.

Accumulating evidence indicates that Smad4 (DPC4) plays a fundamental role in the development and prognosis of several types of cancer. The objective of this study was to conduct a meta-analysis to evaluate whether the loss of Smad4 staining could serve as a prognostic marker.

Circulating tumor cells (CTCs) are metastatic cells disseminated into the bloodstreams. They have been proposed to monitor disease progression for decades. However, the prognostic value of CTCs in gastric cancer (GC) remains controversial. We performed a meta-analysis to investigate the topic.

Metastasis associated in colon cancer-1 (MACC1) is a newly identified oncogene, and increasing evidence has suggested that its overexpression is associated with the development and progression in many tumors. Here, we perform a meta-analysis to assess the relationship between MACC1 overexpression and survival in solid tumors. Eligible studies were searched in Embase, PubMed, and Web of Science databases up to May 2014. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to estimate the impact of MACC1 overexpression on survival using a random-effect model. A total of 20 eligible studies dealing with various tumors were included in the analysis: 17 were dealing with overall survival (OS), 7 were with relapse-free survival (RFS), and 3 were with disease-free survival (DFS). Combined results suggested a strong link between the high MACC1 expression and the poor overall survival (HR 2.11, 95% CI 1.59-2.80, P < 0.001). For relapse-free survival, overexpressed MACC1 was also a significant predictor, with a combined HR of 2.22 (95% CI 1.80-2.74, P < 0.001). Data from the three studies were combined to show that MACC1 overexpression had also an unfavorable impact on disease-free survival (HR 2.94, 95% CI 1.60-5.38, P < 0.001). Publication bias was not significant. The present meta-analysis showed that overexpression of MACC1 was significantly associated with poorer survival in solid tumors.

The functional polymorphism rs4938723 in the promoter region of pri-miR-34b/c is potentially associated with susceptibility to several cancers, including hepatocellular carcinoma, colorectal cancer, and breast cancer. Here we conducted a comprehensive meta-analysis to investigate the association between rs4938723 and cancer risk.

Evidence has shown that single nucleotide polymorphism located in pre-miRNA or mature microRNA may modify various biological processes and affect the processing of carcinogenesis. Published results about the association between miR-146a rs2910164 G/C polymorphism and human gastric cancer susceptibility are inconclusive. The aim of this study was to acquire a more precise effect of the association between the miR-146a rs2910164 polymorphism and gastric risk by meta-analysis.

Head and neck cancers (HNCs) include cancers which arise in oral cavity, pharynx, and larynx. Recent studies have demonstrated that alcohol drinking is an established risk factor for HNC. The alcohol dehydrogenase-1B (ADH1B) plays a major role in the oxidized process of alcohol. To investigate the association of ADH1B Arg47His with HNC in Asian populations, we combined all available studies into a meta-analysis. A total of 2186 cases and 4488 controls were analyzed for this meta-analysis. We used odds ratios (ORs) to assess the strength of the association and 95% confidence intervals (CIs) to give a sense of the precision of the estimate. The ADH1B*47Arg allele was found to be associated with increased risk of HNC in Asians, with the pooled odds ratios (ORs) (Arg/Arg vs. Arg/His + His/His: OR = 2.35, 95% CI = 1.56-3.55, P < 0.0001) in all eight studies. In the subgroup analysis by alcohol consumption, the Arg/Arg vs. Arg/His + His/His genotype was found to be interacted with alcohol consumption, with the OR = 2.44, 95% CI = 1.85-3.20 among ever drinkers. Besides, no significant association was found in non-drinkers. This meta-analysis revealed that ADH1B Arg47His (rs1229984) polymorphism could increase the risk of HNC in Asians significantly.