Association between epidermal growth factor +61 G/A polymorphism and glioma risk in a Chinese Han population

A systematic review of the risk factors associated with the onset and progression of primary brain tumours

The overall aim of this systematic review was to identify risk factors for onset and natural progression, which were shown to increase, decrease, or have a null association with risk of primary brain tumour. For onset, the project was separated into two phases. The first phase consisted of a systematic search of existing systematic reviews and meta-analyses. Moderate to high methodological quality reviews were incorporated and summarized with relevant observational studies published since 2010, identified from a systematic search performed in phase 2. For natural progression, only the first phase was conducted. Standard systematic review methodology was utilized. Based on this review, various genetic variants, pesticide exposures, occupational farming/hairdressing, cured meat consumption and personal hair dye use appear to be associated with increased risk of onset amongst adults. The specific EGF polymorphsm 61-A allele within Caucasian populations and having a history of allergy was associated with a decreased risk. For progression, M1B-1 antigen was shown to increase the risk. High birth weight, pesticide exposure (childhood exposure, and parental occupational exposure) and maternal consumption of cured meat during pregnancy may also increase the risk of onset of childhood brain tumours. Conversely, maternal intake of pre-natal supplements (folic acid) appeared to decrease risk. Children with neurofibromatosis 2 were considered to have worse overall and relapse free survival compared to neurofibromatosis 1, as were those children who had grade III tumours compared to lesser grades.

Association between the epidermal growth factor +61 G/A polymorphism and glioma risk: a meta-analysis

Background

Gliomas account for almost 80% of primary malignant brain tumors. Epidermal growth factor (EGF) is an interesting research candidate in which to look for genetic polymorphisms because of its role in mitogenesis and proliferation. Extensive studies have found that a single nucleotide polymorphism (SNP) +61G/A (rs4444903) in the EGF gene is associated with the susceptibility of glioma, however, the results have been controversial. Furthermore, the association between EGF +61G/A polymorphism with the development and grade progress of glioma has not been established.

Methods

We examined the association of EGF +61G/A polymorphism and glioma by performing a meta-analysis. Nine studies testing the associations between EGF +61G/A polymorphism and risk of glioma with 1758 cases and 2823 controls were retrieved. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the association. The pooled ORs were performed for the allele model, codominant model, dominant model, and recessive model, respectively.

Results

Overall, this meta-analysis showed significant associations between the EGF +61G/A polymorphism and glioma susceptibility in all four genetic models. However, in the stratified analysis by the grade of glioma, we only found this association existed in patients with Grade IV glioblastoma, but not in patients with Grade I-III glioma. We further compared EGF +61G/A polymorphism in patients with glioblastoma and Grade I-III glioma accordingly, the stronger association between the EGF +61G/A polymorphism and the malignancy of glioma was found.

Conclusions

The results of this meta-analysis suggested that the EGF +61G/A polymorphism is associated with both the susceptibility of glioma and the malignance of glioma.

Quantitative assessment of the association between +61A>G polymorphism of epidermal growth factor gene and susceptibility to glioma

Numerous studies have investigated the risk of cancer associated with the polymorphism of epidermal growth factor (EGF) 61A>G, 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 glioma. A comprehensive search was conducted to identify all case-control studies on the EGF +61A>G polymorphism and glioma risk. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to assess the strength of the association. Statistical analysis was performed with the software program Stata (version 12.0). A total of ten eligible studies, including 1,888 cases and 2,836 controls were included in this work. Overall, there was a significant association between EGF +61A>G polymorphism and glioma risk in the allele model (OR = 1.419, 95% CI = 1.144-1.759, P = 0.001). In the subgroup analysis by ethnicity, significant associations were also found in Asian populations under all different genetic models (homozygote model: OR = 1.727, 95% CI = 1.310-2.275, P = 0.000; heterozygote model: OR = 1.202, 95% CI = 1.023-1.413, P = 0.025; dominant model: OR = 1.279, 95% CI = 1.096-1.491, P = 0.002; recessive model: OR = 1.590, 95% CI = 1.221-2.070, P = 0.001; and A-allele versus G-allele OR = 1.600, 95% CI = 1.145-2.236, P = 0.006). However, no significant associations were found among Caucasians in all comparison models. In conclusion, the results suggest that there is a significant association between EGF +61A>G polymorphism and glioma risk among Asians.

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.

A functional +61G/A polymorphism in epidermal growth factor is associated with glioma risk among Asians

Background

Epidermal growth factor (EGF), a potent mitogenic protein, plays an important role in the development of cancers, including glioma. Previous studies showed that the EGF +61G/A polymorphism (rs4444903) may lead to an alteration in EGF production and/or activity, which can result in individual susceptibility to glioma. However, published data regarding the association between the +61G/A polymorphism and glioma risk was contradictory.

Objective

The aim of this study was to perform a meta-analysis of eligible studies to derive precise estimation of the association of EGF +61G/A with glioma risk.

Methods

We performed a pooled analysis of seven published studies that included 1,613 glioma cases and 2,267 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the association. The pooled ORs were performed for codominant model, dominant model, and recessive model, respectively.

Results

Overall, no significant associations between the EGF +61G/A polymorphism and glioma cancer risk were found for AA versus GG (OR = 0.95, 95% CI = 0.62–1.45), GA versus GG (OR = 0.94, 95% CI = 0.72–1.22), AA/GA versus GG (OR = 0.93, 95% CI = 0.70–1.23), and AA versus GA/GG (OR = 1.04, 95% CI = 0.77–1.39). However, in the stratified analysis by ethnicity, the EGF +61G/A polymorphism had a higher risk of glioma development among Asians, but a lower risk among Caucasians.

Conclusions

Taken together, the results suggest that the EGF +61G/A polymorphism may contribute to the susceptibility of glioma in different ethnic groups.

Analysis of EGF+61A>G polymorphism and EGF serum levels in Brazilian glioma patients treated with perillyl alcohol-based therapy

PURPOSE

Malignant gliomas are associated with alteration in EGF/EGFR signaling. Functional EGF+61A>G polymorphism is implicated with risk, recurrence, and progression of glioma. This study aimed to establish a putative association of EGF+61A>G with risk of glioma development, production of angiogenic growth factor EGF, and the response to perillyl alcohol administered by intranasal route.

METHODS

The study included 83 patients with recurrent glioma enrolled in Phase I/II trial for intranasal perillyl alcohol therapy and subjects without cancer (n = 196) as control group. DNA was extracted from blood samples, EGF genotype performed with PCR-RFLP assay, and EGF circulating levels by enzyme immunoassay. Adequate statistical tests were performed to verify associations between polymorphism and glioma risk, and genotype correlation with EGF circulating levels. The log-rank test was also used to evaluate differences on patient survival.

RESULTS

Patients with primary glioblastoma had high frequency of AA genotype (p = 0.037) and A allele (p = 0.037). Increased EGF circulating levels were observed in glioma patients with AA (p = 0.042), AG (p = 0.006), and AA + AG (p = 0.008) genotypes compared with GG. Patients with GG genotype showed increased but not significant (p > 0.05) survival rate, and EGF levels lower than 250 pg/mL was consistently (p = 0.0374) associated with increased survival.

CONCLUSION

Presence of EGF+61A>G polymorphism in Brazilian subjects was associated with glioma risk and increased circulating EGF levels. Better response to perillyl alcohol-based therapy was observed in a group of adult Brazilian subjects with lower EGF levels.

A functional polymorphism in the epidermal growth factor gene is associated with risk for glioma in a Chinese population

Epidermal growth factor (EGF) plays a key role in survival of neural and glial precursor cells. A single nucleotide polymorphism of the EGF gene +61G/A in the 5'-untranslated region has been reported to be associated with susceptibility to glioma. The purpose of this study was to investigate the potential association between EGF +61G/A and brain glioma in a Chinese population. A case-control study involving 180 patients with glioma and 360 controls was done. Polymerase chain reaction restriction fragment-length polymorphism assay was used to analyze the EGF +61G/A genotypes. Patients with glioma had a significantly higher frequency of AA genotype (odds ratio, 2.25; 95% confidence interval, 1.20, 4.21; p=0.01] than controls. When stratified by histologic features and World Health Organization grade of glioma, distribution of each genotype did not significantly differ. Our data suggested that the EGF +61G AA genotype was associated with a higher glioma risk in a Chinese population. This finding is in contrast with previous studies that reported the G allele as a risk factor for glioma in white patients.

Meta-analysis of epidermal growth factor polymorphisms and cancer risk: involving 9,779 cases and 15,932 controls

The epidermal growth factor (EGF) pathway stimulates proliferation and differentiation of epidermal and epithelial tissues, and plays an important role in tumorigenesis. The association between EGF polymorphisms and cancer risk is controversial; thus, we performed this meta-analysis. Overall, 41 case-control studies with 9,779 cases and 15,932 controls were retrieved. We found that EGF +61A/G polymorphism increased overall cancer risk (G allele vs. A allele: OR=1.181, 95% CI=1.077-1.295, P(heterogeneity) < 0.001; GG vs. AA: OR=1.370, 95% CI=1.143-1.641, P(heterogeneity) < 0.001; GG+GA vs. AA: OR=1.175, 95% CI=1.047-1.318, P(heterogeneity) < 0.001). In the stratified analysis by cancer type, the +61 G allele was a risk factor for colorectal cancer, esophageal carcinoma, gastric cancer, and hepatocellular carcinoma. Individuals who carried +61G allele had higher cancer susceptibility in mixed and European racial subgroups. An increased association was detected in the hospital-based subgroup. No significant association was found among EGF -1380A/G, -1744G/A, rs6983267T/G polymorphisms and cancer risk.