SULT1A1 R213H polymorphism and breast cancer risk: a meta-analysis based on 8,454 cases and 11,800 controls

The association between interleukin-1β gene polymorphisms and the risk of breast cancer: a systematic review and meta-analysis

INTRODUCTION

It is reported that there is a close association between interleukin-1β (IL-1β) gene polymorphisms and breast cancer risk. However, the results remain controversial.

MATERIAL AND METHODS

Eligible published articles were searched in PubMed, Embase, and Web of Science databases up to June 2018. Odds ratios with 95% confidence intervals were used to identify potential links between IL-1β genetic polymorphisms and the risk of breast cancer.

RESULTS

From our results, we found that three common polymorphisms in IL-1β (rs16944, rs1143634, rs1143627) had no significant associations with breast cancer risk in all genetic models. Based on the analysis from ethnic subgroups, there was a higher risk of breast cancer for rs16944 polymorphism in the recessive model and heterozygous model among Asians (TT vs. CC+CT: 1.229, 95% CI: 1.063-1.422, p = 0.005; TT vs. CT: 1.211, 95% CI: 1.057-1.388, p = 0.006). For the rs1143627 polymorphism, a significantly decreased breast cancer risk was observed in the dominant model only in Asians (CT+TT vs. CC: OR = 0.944, 95% CI: 0.897-0.994, p = 0.027). After stratifying patients according to the menopausal state, we found that polymorphism of rs1143627 correlated with reduced breast cancer risk among post-menopausal women in three genotype models: allele, recessive model and homozygous model (T vs C: 0.859, 95% CI: 0.753-0.98, p = 0.024; TT vs. CC+CT: 0.727, 95% CI: 0.576-0.918, p = 0.007; TT vs. CC: 0.743, 95% CI: 0.626-0.882, p = 0.001). As for other analyses with reference to source of controls and genotyping methods, no significant association between IL-1β polymorphism and breast cancer risk was demonstrated.

CONCLUSIONS

The rs16944 and rs1143627 polymorphisms are significantly associated with the risk of breast cancer only in Asian people and in post-menopausal women respectively.

Structural and Dynamic Characterizations Highlight the Deleterious Role of SULT1A1 R213H Polymorphism in Substrate Binding

Sulfotransferase 1A1 (SULT1A1) is responsible for catalyzing various types of endogenous and exogenous compounds. Accumulating data indicates that the polymorphism rs9282861 (R213H) is responsible for inefficient enzymatic activity and associated with cancer progression. To characterize the detailed functional consequences of this mutation behind the loss-of-function of SULT1A1, the present study deployed molecular dynamics simulation to get insights into changes in the conformation and binding energy. The dynamics scenario of SULT1A1 in both wild and mutated types as well as with and without ligand showed that R213H induced local conformational changes, especially in the substrate-binding loop rather than impairing overall stability of the protein structure. The higher conformational changes were observed in the loop3 (residues, 235-263), turning loop conformation to A-helix and B-bridge, which ultimately disrupted the plasticity of the active site. This alteration reduced the binding site volume and hydrophobicity to decrease the binding affinity of the enzyme to substrates, which was highlighted by the MM-PBSA binding energy analysis. These findings highlight the key insights of structural consequences caused by R213H mutation, which would enrich the understanding regarding the role of SULT1A1 mutation in cancer development and also xenobiotics management to individuals in the different treatment stages.

Genetics of breast cancer in African populations: a literature review

Breast cancer (BC) is one of the most complex, diverse and leading cause of death in women worldwide. The present investigation aims to explore genes panel associated with BC in different African regions, and compare them to those studied worldwide.

We extracted relevant information from 43 studies performed in Africa using the following criteria: case-control study, association between genetic variations and BC risk. Data were provided on mutations and polymorphisms associated with BC without fixing a specific date. Case-only studies and clinical trials were excluded.

Our study revealed that the majority of African BC genetic studies remain restricted to the investigation of BRCA1 and BRCA2 genes and differences in their mutations spectrum. Therefore, it is necessary to encourage African researchers to characterize more genes involved in BC using methods generating global information such as next-generation sequencing in order to guide specific and more effective therapeutic strategies for the African community.

Expression of sulfotransferase SULT1A1 in cancer cells predicts susceptibility to the novel anticancer agent NSC-743380

The small molecule anticancer agent NSC-743380 modulates functions of multiple cancer-related pathways and is highly active in a subset of cancer cell lines in the NCI-60 cell line panel. It also has promising in vivo anticancer activity. However, the mechanisms underlying NSC-743380's selective anticancer activity remain uncharacterized. To determine biomarkers that may be used to identify responders to this novel anticancer agent, we performed correlation analysis on NSC-743380's anticancer activity and the gene expression levels in NCI-60 cell lines and characterized the functions of the top associated genes in NSC-743380–mediated anticancer activity. We found sulfotransferase SULT1A1 is causally associated with NSC-743380's anticancer activity. SULT1A1 was expressed in NSC-743380–sensitive cell lines but was undetectable in resistant cancer cells. Ectopic expression of SULT1A1 in NSC743380 resistant cancer cells dramatically sensitized the resistant cells to NSC-743380. Knockdown of the SULT1A1 in the NSC-743380 sensitive cancer cell line rendered it resistance to NSC-743380. The SULT1A1 protein levels in cell lysates from 18 leukemia cell lines reliably predicted the susceptibility of the cell lines to NSC-743380. Thus, expression of SULT1A1 in cancer cells is required for NSC-743380's anticancer activity and can be used as a biomarker for identification of NSC-743380 responders.

Association of SULT1A1 Arg²¹³His polymorphism with male breast cancer risk: results from a multicenter study in Italy

Male breast cancer (MBC) is rare and poorly understood. Like female breast cancer (FBC), MBCs are highly sensitive to hormonal changes, and hyperestrogenism, specifically, represents a major risk factor for MBC. MBC is considered similar to late-onset, post-menopausal estrogen/progesteron receptors positive FBC (ER+/PR+). Sulfotransferase 1A1 (SULT1A1) is an enzyme involved in the metabolism of estrogens. Recently, SULT1A1 common functional polymorphism Arg(213)His (638G>A) variant has been found to be associated with increased breast cancer (BC) risk, particularly in post-menopausal women. For this reason, we decided to explore whether SULT1A1 Arg(213)His could exert an effect on MBC development. The primary aim of this study was to evaluate the influence of the SULT1A1 Arg(213)His polymorphism on MBC risk. The secondary aim was to investigate possible associations with relevant clinical-pathologic features of MBC. A total of 394 MBC cases and 786 healthy male controls were genotyped for SULT1A1 Arg(213)His polymorphism by PCR-RFLP and high-resolution melting analysis. All MBC cases were characterized for relevant clinical-pathologic features. A significant difference in the distribution of SULT1A1 Arg(213)His genotypes was found between MBC cases and controls (P < 0.0001). The analysis of genotype-specific risk showed a significant increased MBC risk in individuals with G/A (OR 1.97, 95% CI 1.50-2.59; P < 0.0001) and A/A (OR 3.09, 95% CI 1.83-5.23; P < 0.0001) genotypes in comparison to wild-type genotype, under co-dominant model. A significant association between SULT1A1 risk genotypes and HER2 status emerged. Results indicate that SULT1A1 Arg(213)His may act as a low-penetrance risk allele for developing MBC and could be associated with a specific tumor subtype associated with HER2 overexpression.

Sulfotransferase SULT1A1 Arg213His polymorphism with cancer risk: a meta-analysis of 53 case-control studies

Background

The SULT1A1 Arg213His (rs9282861) polymorphism is reported to be associated with many kinds of cancer risk. However, the findings are conflicting. For better understanding this SNP site and cancer risk, we summarized available data and performed this meta-analysis.

Methods

Data were collected from the following electronic databases: PubMed, Web of Knowledge and CNKI. The association was assessed by odd ratio (OR) and the corresponding 95% confidence interval (95% CI).

Results

A total of 53 studies including 16733 cancer patients and 23334 controls based on the search criteria were analyzed. Overall, we found SULT1A1 Arg213His polymorphism can increase cancer risk under heterozygous (OR = 1.09, 95% CI = 1.01–1.18, P = 0.040), dominant (OR = 1.10, 95% CI = 1.01–1.19, P = 0.021) and allelic (OR = 1.08, 95% CI = 1.02–1.16, P = 0.015) models. In subgroup analyses, significant associations were observed in upper aero digestive tract (UADT) cancer (heterozygous model: OR = 1.62, 95% CI = 1.11–2.35, P = 0.012; dominant model: OR = 1.63, 95% CI = 1.13–2.35, P = 0.009; allelic model: OR = 1.52, 95% CI = 1.10–2.11, P = 0.012) and Indians (recessive model: OR = 1.93, 95% CI = 1.22–3.07, P = 0.005) subgroups. Hospital based study also showed marginally significant association. In the breast cancer subgroup, ethnicity and publication year revealed by meta-regression analysis and one study found by sensitivity analysis were the main sources of heterogeneity. The association between SULT1A1 Arg213His and breast cancer risk was not significant. No publication bias was detected.

Conclusions

The present meta-analysis suggests that SULT1A1 Arg213His polymorphism plays an important role in carcinogenesis, which may be a genetic factor affecting individual susceptibility to UADT cancer. SULT1A1 Arg213His didn't show any association with breast cancer, but the possible risk in Asian population needs further investigation.

Ethnic background and genetic variation in the evaluation of cancer risk: a systematic review

The clinical use of genetic variation in the evaluation of cancer risk is expanding, and thus understanding how determinants of cancer susceptibility identified in one population can be applied to another is of growing importance. However there is considerable debate on the relevance of ethnic background in clinical genetics, reflecting both the significance and complexity of genetic heritage. We address this via a systematic review of reported associations with cancer risk for 82 markers in 68 studies across six different cancer types, comparing association results between ethnic groups and examining linkage disequilibrium between risk alleles and nearby genetic loci. We find that the relevance of ethnic background depends on the question. If asked whether the association of variants with disease risk is conserved across ethnic boundaries, we find that the answer is yes, the majority of markers show insignificant variability in association with cancer risk across ethnic groups. However if the question is whether a significant association between a variant and cancer risk is likely to reproduce, the answer is no, most markers do not validate in an ethnic group other than the discovery cohort's ancestry. This lack of reproducibility is not attributable to studies being inadequately populated due to low allele frequency in other ethnic groups. Instead, differences in local genomic structure between ethnic groups are associated with the strength of association with cancer risk and therefore confound interpretation of the implied physiologic association tracked by the disease allele. This suggest that a biological association for cancer risk alleles may be broadly consistent across ethnic boundaries, but reproduction of a clinical study in another ethnic group is uncommon, in part due to confounding genomic architecture. As clinical studies are increasingly performed globally this has important implications for how cancer risk stratifiers should be studied and employed.

Sulfotransferase genetic variation: from cancer risk to treatment response

Cytosolic sulfotransferases (SULTs) are phase II detoxification enzymes that are involved in the biotransformation of a wide variety of structurally diverse endo- and xenobiotics. Single-nucleotide polymorphisms (SNPs) in SULTs can alter the phenotype of the translated proteins. SNPs in some SULTs are fairly uncommon in the population, but some, most notably for SULT isoform 1A1, are commonly found and have been associated with cancer risk for a variety of tumor sites and also with response to therapeutic agents. SNPs in many SULTs vary by ethnicity, another factor that could influence SULT-associated disease risk and pharmacogenetics. This review surveys the current knowledge of SULT genetic variability in relation to cancer risk and response to therapy, focusing primarily on SULT1A1.

SULT1A1 Arg213His polymorphism and lung cancer risk: a meta-analysis

BACKGROUND

The SULT1A1 Arg213His polymorphism is reported to be associated with lung cancer risk. However, this relationship remains controversial. For better understanding a meta-analysis was therefore performed.

METHODS

An extensive search was performed to identify all case-control studies investigating association between SULT1A1 Arg213His polymorphism and lung cancer risk. The strength was assessed by odds ratio (OR) with the corresponding 95% confidence interval (95%CI).

RESULTS

A total of five publications covering 1,669 cases and 1,890 controls were included in this meta-analysis. No significant association between SULT1A1 Arg213His polymorphism and lung cancer risk was observed in overall comparisons in all genetic models (dominant model: OR=1.33, 95%CI=1.00-1.76, P=0.05; additive model: OR=1.30, 95%CI=0.93-1.81, P=0.12; recessive model: OR=1.21, 95%CI=0.89-1.66, P=0.23). However, on subgroup analysis, an elevated risk in mixed populations with variant His allele was revealed in the dominant model (OR=1.66, 95% CI=1.06-2.62, P=0.03). Furthermore, the SULT1A1 Arg213His polymorphism was associated with an increased risk of lung cancer in both females and males in the dominant model (females: OR=1.72, 95%CI=1.29-2.27, P=0.00; males: OR=1.46, 95%CI=1.19-1.78, P=0.00). No significant association between this polymorphism and different smoking status (smokers and non-smokers) and the other ethnicities (Asians and Caucasians) was shown.

CONCLUSIONS

The results of this meta-analysis indicate that the SULT1A1 Arg213His polymorphism is not associated with lung cancer risk in Asians and Caucasians, but possible elevation for genotype (GA/AA) in mixed populations and males and females needs further investigation.

Passive cigarette smoke exposure during various periods of life, genetic variants, and breast cancer risk among never smokers

The association between passive cigarette smoke exposure and breast cancer risk is inconclusive and may be modified by genotype. The authors investigated lifetime passive cigarette smoke exposures, 36 variants in 12 carcinogen-metabolizing genes, and breast cancer risk among Ontario, Canada, women who had never smoked (2003-2004). DNA (saliva) was available for 920 breast cancer cases and 960 controls. Detailed information about passive smoke exposure was collected for multiple age periods (childhood, teenage years, and adulthood) and environments (home, work, and social). Adjusted odds ratios and 95% confidence intervals were estimated by multivariable logistic regression, and statistical interactions were assessed using the likelihood ratio test. Among postmenopausal women, most associations between passive smoke and breast cancer risk were null, whereas among premenopausal women, nonsignificant positive associations were observed. Significant interactions were observed between certain types of passive smoke exposure and genetic variants in CYP2E1, NAT2, and UGT1A7. While these interactions were statistically significant, the magnitudes of the effect estimates were not consistent or easily interpretable, suggesting that they were perhaps due to chance. Although the results of this study were largely null, it is possible that premenopausal women exposed to passive smoke or carrying certain genetic variants may be at higher risk of breast cancer.

SULT1A1 Arg213His polymorphism, smoked meat, and breast cancer risk: a case-control study and meta-analysis

SULT1A1 is involved in both detoxification of estrogens and bioactivation of carcinogens in smoked meat. SULT1A1 Arg213His polymorphism's effect on breast cancer risk is still unclear. We recruited 400 case-control pairs to investigate the association between SULT1A1 genotypes and breast cancer risk, and the combined effect of SULT1A1 polymorphism and daily intake of smoked meat. Participants were questioned about their dietary habits and other risk factors, and their SULT1A1 genotypes were determined. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated by multivariable unconditional logistic regression. We also performed a meta-analysis of relevant published studies to test these associations. In the case-control study, no significant associations were observed between SULT1A1 polymorphism and breast cancer risk. In the meta-analysis, SULT1A1 His/His genotype slightly increased risk among both overall and postmenopausal women (OR(pooled-overall)=1.12, 95% CI: 1.02-1.24; OR(pooled-post)=1.17, 95% CI: 1.03-1.32). A larger positive association was observed in Asian populations (OR(pooled-Asian)=2.01, 95% CI: 1.24-3.26). In our case-control study, high energy-adjusted daily intake of smoked meat was significantly associated with breast cancer risk in overall, pre- and postmenopausal women (aORs: 2.31-3.13, OR 95% CIs exclude 1). High smoked meat intake interacted positively with the His variant allele (all γ>1). These results correlated with those of the meta-analysis (γ(pooled-overall)=1.27). The SULT1A1 His/His genotype may increase the risk of breast cancer among Asian women, and dietary exposure to heterocyclic amines and polycyclic aromatic hydrocarbons, along with the SULT1A1 His/His variant genotype, may synergistically increase the risk of breast cancer.

SULT1A1 Arg213His polymorphism and susceptibility of environment-related cancers: a meta analysis of 5,915 cases and 7,900 controls

The common genetic polymorphism for SULT1A1 is Arg213His polymorphism, which may affect the sulfation process of various environmental carcinogens and thus is suggested to be related to susceptibility of several cancers. However, studies on the association between SULT1A1 Arg213His polymorphism and cancer susceptibility are inconsistent. To assess the relationship between Arg213His polymorphism and environmental-related cancers systematically, we performed a meta analysis from 20 case-control studies including 5,915 cases and 7,900 controls. The odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of risk, we found a significant association between SULT1A1 Arg213His polymorphism and environment-related cancers (for dominant model: OR 1.22, 95% CI 1.07-1.39, P = 0.003). When stratified by ethnicity, a significant risk was observed in Asian cases, compared with controls (for dominant model: OR 1.69, 95% CI 1.17-2.43, P = 0.005). When we chose only smokers in our analysis, we also found a significantly increased risk between Arg213His polymorphism and susceptibility of environment-related cancers for participants exposed to a smoking environment. In conclusion, SULT1A1 Arg213His polymorphism, ethnicity, smoking may modulate environment-related cancer risk. Studies on gene-gene interactions in the sequential or concurrent metabolic pathway and gene-environment interactions need to be further conducted to explore the susceptibility of cancer occurrence.

Current evidence on the relationship between four polymorphisms in the matrix metalloproteinases (MMP) gene and breast cancer risk: a meta-analysis

The matrix metalloproteinases (MMP) can degrade various components of the extracellular matrix and its functional genetic polymorphisms may be associated with breast cancer risk. However, this relationship remains controversial. A meta-analysis was conducted in order to investigate the potential association between four polymorphisms in the MMP gene and breast cancer risk. A database search yielded a total of 9 studies involving 2,597 cases and 2,618 controls. Four polymorphisms were included in the meta-analysis: MMP-1 -1607 2G/1G (rs1799750), MMP-2 -1306 C/T (rs243865), MMP-3 -1171 6A/5A (rs3025058) and MMP-9 -1562 C/T (rs3918242). Crude odds ratios (OR) with 95% confidence intervals (CI) were used to assess the strength of association. When all the studies were pooled into the meta-analysis, we found that breast cancer cases had a significantly higher frequency of CC genotype (OR = 1.27, 95% CI = 1.10, 1.47; P = 0.001) and lower frequency of CT genotype (OR = 0.78, 95% CI = 0.67, 0.91; P = 0.001) of MMP-2. No significant difference was found in any genotype of MMP-1, MMP-3 or MMP-9. In conclusion, this meta-analysis suggested that MMP-2 -1306 C/T polymorphism may contribute to breast cancer susceptibility. More studies were needed especially in Asians in the future.

The association of polymorphisms in hormone metabolism pathway genes, menopausal hormone therapy, and breast cancer risk: a nested case-control study in the California Teachers Study cohort

Introduction

The female sex steroids estrogen and progesterone are important in breast cancer etiology. It therefore seems plausible that variation in genes involved in metabolism of these hormones may affect breast cancer risk, and that these associations may vary depending on menopausal status and use of hormone therapy.

Methods

We conducted a nested case-control study of breast cancer in the California Teachers Study cohort. We analyzed 317 tagging single nucleotide polymorphisms (SNPs) in 24 hormone pathway genes in 2746 non-Hispanic white women: 1351 cases and 1395 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by fitting conditional logistic regression models using all women or subgroups of women defined by menopausal status and hormone therapy use. P values were adjusted for multiple correlated tests (P_ACT).

Results

The strongest associations were observed for SNPs in SLCO1B1, a solute carrier organic anion transporter gene, which transports estradiol-17β-glucuronide and estrone-3-sulfate from the blood into hepatocytes. Ten of 38 tagging SNPs of SLCO1B1 showed significant associations with postmenopausal breast cancer risk; 5 SNPs (rs11045777, rs11045773, rs16923519, rs4149057, rs11045884) remained statistically significant after adjusting for multiple testing within this gene (P_ACT = 0.019-0.046). In postmenopausal women who were using combined estrogen-progestin therapy (EPT) at cohort enrollment, the OR of breast cancer was 2.31 (95% CI = 1.47-3.62) per minor allele of rs4149013 in SLCO1B1 (P = 0.0003; within-gene P_ACT = 0.002; overall P_ACT = 0.023). SNPs in other hormone pathway genes evaluated in this study were not associated with breast cancer risk in premenopausal or postmenopausal women.

Conclusions

We found evidence that genetic variation in SLCO1B1 is associated with breast cancer risk in postmenopausal women, particularly among those using EPT.

Association of sulfotransferase SULT1A1 with breast cancer risk: a meta-analysis of case-control studies with subgroups of ethnic and menopausal statue

BACKGROUND

Sulfotransferase (SULT) plays an important role in the formation of estrogen which is usually conferred as a risk factor for breast cancer. Polymorphism of the SULT1A1 may be closely associated with breast cancer. However, studies on the association between polymorphism and breast cancer have yielded inconsistent results. We performed a meta-analysis including ethnic subgroup and menopausal statue subgroup to investigate the association of SULT1A1 Arg213His polymorphism with breast cancer.

METHODS

PubMed, EBSCO and Web of Science databases were searched for the correlative articles up to January 2010 (10362 breast cancer patients and 14250 controls). The risk (odds ratio, OR) was used to estimate the association between SULT1A1 polymorphism and breast cancer risk. All of the data from each study use either fixed-effects or random-effects.

RESULTS

We found that SULT1A1 Arg213His had no exact effect to increase the risk of breast cancer (OR = 1.07, 95% CI: 0.97-1.17, P = 0.164), but it did increase the risk of breast cancer among postmenopausal women in the dominant model (OR = 1.28, 95%CI: 1.04-1.58, P = 0.019). No similar effect was found among premenopausal breast cancer women (OR = 1.06, 95%CI: 0.88-1.27, P = 0.537). There was a significant increase in breast cancer risk among Asian women (OR = 2.03, 95% CI: 1.00-4.14, P = 0.051) but not Caucasian women in recessive model. There was publication bias among postmenopausal women subgroup (P = 0.002), however by using the trim and fill method, if the publication bias was the only source of the funnel plot asymmetry, it needed two more studies to be symmetrical. The value of Log OR did not change too much after the adjustment and the fail-safe number of missing studies that would bring the P-value changed was 17.

CONCLUSIONS

We concluded that the polymorphism of SULT1A1 Arg213His might be one of the high risk factors for breast cancer in Asian women and in postmenopausal women for all races. We should point out that the publication bias among postmenopausal women may partly account for the result, but the conclusion might not affected deeply by the publication bias.

Methylenetetrahydrofolate reductase polymorphisms and breast cancer risk: a meta-analysis from 41 studies with 16,480 cases and 22,388 controls

The association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and breast cancer risk has been widely reported, but results were inconsistent and underpowered. To clarify the effects of MTHFR polymorphisms on the risk of breast cancer, an updated meta-analysis of all available studies relating C677T and/or A1298C polymorphisms of MTHFR gene to the risk of breast cancer was conducted. Eligible articles were identified by search of databases including MEDLINE, PubMed, Web of Science, EMBASE and Chinese Biomedical Literature database (CBM) for the period up to January 2010. Finally, a total of 41 studies with 16,480 cases and 22,388 controls were included, all for C677T polymorphism and 20 with 12,170 cases and 15,865 controls for A1298C polymorphism. The pooled ORs were performed for the allele contrasts, additive genetic model, dominant genetic model, and recessive genetic model, respectively. Subgroup analyses were also performed by ethnicity and menopausal status. With respect to C677T polymorphism, significantly elevated breast cancer risk was found in overall analysis (T vs. C: OR = 1.041, 95% CI = 1.009-1.073; TT vs. CC: OR = 1.132, 95% CI = 1.019-1.259; TT vs. CC + CT: OR = 1.119, 95% CI = 1.014-1.236); in the subgroup analysis by ethnicity, significantly increased risk was found in East Asian population (T vs. C: OR = 1.121, 95% CI = 1.016-1.237; TT vs. CC: OR = 1.331, 95% CI = 1.073-1.650; TT vs. CC + CT: OR = 1.265, 95% CI = 1.058-1.513) but not in Caucasian population; in the subgroup analysis by menopausal status, no statistically significant association was found. With respect to A1298C polymorphism, no significant association with breast cancer risk was demonstrated in overall, ethnicity- and menopausal status-based population. It can be concluded that potentially functional MTHFR C677T polymorphism may play a low penetrance role in the development of breast cancer.

No association between SOD2 Val16Ala polymorphism and breast cancer susceptibility: a meta-analysis based on 9,710 cases and 11,041 controls

Breast cancer is the most common cancer in women worldwide, but its etiology is still unclear. It is believed that oxidative stress plays an essential role in the development of breast cancer, while SOD2 is one of the primary enzymes that directly convert potential harmful oxidizing species to harmless metabolites. The association of SOD2 Val16Ala polymorphism and breast cancer risk has been widely reported, but results of previous studies were somewhat contradictory and underpowered. To overcome the limitations of individual study and to understand the real situation, we conducted a systematic review and meta-analysis toward the association between SOD2 Val16Ala polymorphism and breast cancer. Through retrieving MEDLINE, PubMed, Embase, and Web of Science, a total of 17 studies with 9,710 cases and 11,041 controls were identified. The results showed that no significant associations were found for the allele contrast (allele Ala vs. allele Val: OR = 1.020, 95% CI = 0.979-1.062), additive genetic model (Ala/Ala vs. Val/Val: OR = 1.091, 95% CI = 0.969-1.229), dominant genetic model (Ala/Ala +Ala/Val vs. Val/Val: OR = 1.045, 95% CI = 0.961-1.136), and recessive genetic model (Ala/Ala vs. Val/Val +Ala/Val: OR = 1.027, 95% CI = 0.956-1.102). In the stratified analysis by ethnicity and menopausal status, significant associations were also not detected in all genetic models. Conclusively, this meta-analysis strongly suggests that SOD2 Val16Ala polymorphism is not associated with breast cancer susceptibility.