BRCA2 N372H polymorphism and breast cancer susceptibility: a meta-analysis involving 44,903 subjects

Prevalence of BRCA1, BRCA2, and PALB2 genomic alterations among 924 Taiwanese breast cancer assays with tumor-only targeted sequencing: extended data analysis from the VGH-TAYLOR study

BACKGROUND

The homologous recombination (HR) repair pathway for DNA damage, particularly the BRCA1 and BRCA2 genes, has become a target for cancer therapy, with poly ADP-ribose polymerase (PARP) inhibitors showing significant outcomes in treating germline BRCA1/2 (gBRCA1/2) mutated breast cancer. Recent studies suggest that some patients with somatic BRCA1/2 (sBRCA1/2) mutation or mutations in HR-related genes other than BRCA1/2 may benefit from PARP inhibitors as well, particularly those with PALB2 mutations. The current analysis aims to evaluate the prevalence of genetic alterations specific to BRCA1, BRCA2, and PALB2 in a large cohort of Taiwanese breast cancer patients through tumor-targeted sequencing.

METHODS

A total of 924 consecutive assays from 879 Taiwanese breast cancer patients underwent tumor-targeted sequencing (Thermo Fisher Oncomine Comprehensive Assay v3). We evaluated BRCA1, BRCA2, and PALB2 mutational profiles, with variants annotated and curated by the ClinVAR, the Oncomine™ Knowledgebase Reporter, and the OncoKB™. We also conducted reflex germline testing using either whole exome sequencing (WES) or whole genome sequencing (WGS), which is ongoing.

RESULTS

Among the 879 patients analyzed (924 assays), 130 had positive mutations in BRCA1 (3.1%), BRCA2 (8.6%), and PALB2 (5.2%), with a total of 14.8% having genetic alterations. Co-occurrence was noted between BRCA1/BRCA2, BRCA1/PALB2, and BRCA2/PALB2 mutations. In BRCA1-mutated samples, only p.K654fs was observed in three patients, while other variants were observed no more than twice. For BRCA2, p.N372H was the most common (26 patients), followed by p.S2186fs, p.V2466A, and p.X159_splice (5 times each). For PALB2, p.I887fs was the most common mutation (30 patients). This study identified 176 amino acid changes; 60.2% (106) were not documented in either ClinVAR or the Oncomine™ Knowledgebase Reporter. Using the OncoKB™ for annotation, 171 (97.2%) were found to have clinical implications. For the result of reflex germline testing, three variants (BRCA1 c.1969_1970del, BRCA1 c.3629_3630del, BRCA2 c.8755-1G > C) were annotated as Pathogenic/Likely pathogenic (P/LP) variants by ClinVar and as likely loss-of-function or likely oncogenic by OncoKB; while one variant (PALB2 c.448C > T) was not found in ClinVar but was annotated as likely loss-of-function or likely oncogenic by OncoKB.

CONCLUSION

Our study depicted the mutational patterns of BRCA1, BRCA2, and PALB2 in Taiwanese breast cancer patients through tumor-only sequencing. This highlights the growing importance of BRCA1/2 and PALB2 alterations in breast cancer susceptibility risk and the treatment of index patients. We also emphasized the need to meticulously annotate variants in cancer-driver genes as well as actionable mutations across multiple databases.

Short Breastfeeding Duration is Associated With Premature Onset of Female Breast Cancer

Currently, there is controversy concerning potential factors that contribute to the development of breast cancer. Our study analyzed the possible association between weight status, cigarette consumption, lactation period, serum estrogen levels, family history of breast cancer, and age at breast cancer diagnosis. We conducted a retrospective study at a University Hospital in Granada (Spain) by consulting the medical records of 524 women aged 19 to 91 years, all of them diagnosed and treated for breast cancer from 2011 to 2019. Our findings indicated that in non-morbidly obese females who were also non-smokers, a maternal lactation period of more than 3 months (p = .013) and the absence of family antecedents of cancer (p = .025) were statistically significant factors that led to a more advanced age at breast cancer diagnosis. Thus, maternal lactation seems to have a potential protective effect on breast cancer.

Association between the BRCA2 rs144848 polymorphism and cancer susceptibility: a meta-analysis

The BRCA2 gene plays an important role in cancer carcinogenesis, and polymorphisms in this gene have been associated with cancer risk. The BRCA2 rs144848 polymorphism has been associated with several cancers, but results have been inconsistent. In the present study, a meta-analysis was performed to assess the association between the rs144848 polymorphism and cancer risk. Literature was searched from the databases of PubMed, Embase and Google Scholar before April 2016. The fixed or random effects model was used to calculate pooled odd ratios on the basis of heterogeneity. Meta-regression, sensitivity analysis, subgroup analysis and publication bias assessment were also performed using STATA 11.0 software according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2009. A total of 40 relevant studies from 30 publications including 34,911 cases and 48,329 controls were included in the final meta-analysis. Among them, 22 studies focused on breast cancer, seven on ovarian cancer, five on non-Hodgkin lymphoma, and the remaining six studies examined various other cancers. The meta-analysis results showed that there were significant associations between the rs144848 polymorphism and cancer risk in all genetic models. Stratified by cancer type, the rs144848 polymorphism was associated with non-Hodgkin lymphoma. Stratified by study design, the allele model was associated with breast cancer risk in population-based studies. The meta-analysis suggests that the BRCA2 rs144848 polymorphism may play a role in cancer risk. Further well-designed studies are warranted to confirm these results.

Evaluating genetic variants associated with breast cancer risk in high and moderate-penetrance genes in Asians

Over the past 20 years, high-penetrance pathogenic mutations in genes BRCA1, BRCA2, TP53, PTEN, STK11 and CDH1 and moderate-penetrance mutations in genes CHEK2, ATM, BRIP1, PALB2, RAD51C, RAD50 and NBN have been identified for breast cancer. In this study, we investigated whether there are additional variants in these 13 genes associated with breast cancer among women of Asian ancestry. We analyzed up to 654 single nucleotide polymorphisms (SNPs) from 6269 cases and 6624 controls of Asian descent included in the Breast Cancer Association Consortium (BCAC), and up to 236 SNPs from 5794 cases and 5529 controls included in the Shanghai Breast Cancer Genetics Study (SBCGS). We found three missense variants with minor allele frequency (MAF) <0.05: rs80358978 (Gly2508Ser), rs80359065 (Lys2729Asn) and rs11571653 (Met784Val) in the BRCA2 gene, showing statistically significant associations with breast cancer risk, with P-values of 1.2 × 10-4, 1.0 × 10-3 and 5.0 × 10-3, respectively. In addition, we found four low-frequency variants (rs8176085, rs799923, rs8176173 and rs8176258) in the BRCA1 gene, one common variant in the CHEK2 gene (rs9620817), and one common variant in the PALB2 gene (rs13330119) associated with breast cancer risk at P < 0.01. Our study identified several new risk variants in BRCA1, BRCA2, CHEK2, and PALB2 genes in relation to breast cancer risk in Asian women. These results provide further insights that, in addition to the high/moderate penetrance mutations, other low-penetrance variants in these genes may also contribute to breast cancer risk.

Modulation of HAT activity by the BRCA2 N372H variation is a novel mechanism of paclitaxel resistance in breast cancer cell lines

Paclitaxel stabilizes microtubule polymerization, enhances microtubule assembly, and G2/M arrests, leading to cell death. Paclitaxel resistance has been attributed to a variety of mechanisms. In the present study, we define a new resistance mechanism to paclitaxel based on BRCA2 variation. Chemo-sensitivity to paclitaxel based on the variations was compared. Restoration of paclitaxel sensitivity was induced indirectly with combined treatment of paclitaxel and HDAC inhibitor. Variant and wild type of BRCA2 clones were obtained from wild and variant cells, respectively. Chemo-sensitivity, P/CAF and BubR1 expression and acetylation, BRCA2-P/CAF and BRCA2-BubR1 interactions, and HAT activities of the clones with BRCA2 variation were compared. We identified an association between chemo-sensitivity and BRCA2 N372H variation. The IC₅₀ of paclitaxel in heterozygous variation was higher than that of wild type. There were no differences in basic expression levels of BRCA2 among variant types. However, P/CAF expression, of BRCA2-P/CAF interaction, and HAT activity were significantly lower in heterozygous variants than in the wild type. After HDAC inhibitor treatment, HAT activity and paclitaxel sensitivity were restored in variant cells. Cell lines transformed from wild to variant or from variant to wild showed reciprocal changes in P/CAF expression, BRCA2-P/CAF interaction, HAT activity, and paclitaxel sensitivity. Forced expression of the BRCA2 heterozygous variant induced paclitaxel resistance due to altered HAT activity (p<0.001). This was reversed by the TSA combination. Restoration of wild BRCA2 from variant type improved paclitaxel sensitivity (p<0.001). Modulation of HAT activity by BRCA2 N372H variation is a new mechanism of paclitaxel resistance in breast cancer.

Spectrum of genetic variants of BRCA1 and BRCA2 in a German single center study

BACKGROUND

Determination of mutation status of BRCA1 and BRCA2 has become part of the clinical routine. However, the spectrum of genetic variants differs between populations. The aim of this study was to deliver a comprehensive description of all detected variants.

METHODS

In families fulfilling one of the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC) criteria for genetic testing, one affected was chosen for analysis. DNA of blood lymphocytes was amplified by PCR and prescreened by DHPLC. Aberrant fragments were sequenced. All coding exons and splice sites of BRCA1 and BRCA2 were analyzed. Screening for large rearrangements in both genes was performed by MLPA.

RESULTS

Of 523 index patients, 121 (23.1%) were found to carry a pathogenic or likely pathogenic (class 4/5) mutation. A variant of unknown significance (VUS) was detected in 73/523 patients (13.9%). Two mutations p.Gln1756Profs*74 and p.Cys61Gly comprised 42.3% (n = 33/78) of all detected pathogenic mutations in BRCA1. Most of the other mutations were unique mutations. The most frequently detected mutation in BRCA2 was p.Val1283Lys (13.9%; n = 6/43). Altogether, 101 different neutral genetic variants were counted in BRCA1 (n = 35) and in BRCA2 (n = 66).

CONCLUSION

The two most frequently detected mutations are founder mutations in Poland and Czech Republic. More similarities seem to be shared with our direct neighbor countries compared to other European countries. For comparison of the extended genotype, a shared database is needed.

BRCA2 N372H Polymorphism and Risk of Epithelial Ovarian Cancer: An Updated Meta-Analysis With 2344 Cases and 9672 Controls

The BRCA2 N372H is the only common polymorphism that leads to the amino acid change based on the reports up to date. Previous studies explored the relationship between the single nucleotide polymorphism and ovarian cancer risk, but the results were inconsistent or inconclusive.To investigate the association between N372H in BRCA2 gene and ovarian cancer susceptibility, a systematic literature search was performed for related publications in the databases of PubMed, Gene, and Google Scholar.Total 2344 cases and 9672 controls in eligible studies were included in this meta-analysis. χ -based Q test and an I index were used to identify the heterogeneous records. Potential publication biases were assessed by Begg and Egger tests.In the overall analysis, the results showed a significant association between BRCA2 codon 372 polymorphism and increased risk of ovarian cancer (HH versus NN: odds ratio (OR) = 1.22, 95% confidence interval (CI) 1.01-1.48, P = 0.037). In the Australia subgroup analysis, significant association was also detected (HH versus NN: OR = 1.40, 95% CI 1.04-1.87, P = 0.026). The subgroup analysis for serous cancer subgroup showed that the significant association could be detected under recessive model (OR = 1.38, 95% CI, 1.01-1.89, P = 0.04) and under homozygote comparison (OR = 1.46, 95% CI, 1.06-2.01, P = 0.022).Our meta-analysis suggests that the N372H polymorphism is associated with susceptibility of ovarian cancer. The allele H might increase the risk of ovarian cancer, especially, for ovarian cancers of the serous subtype.

Association of BRCA2 N372H polymorphism with cancer susceptibility: a comprehensive review and meta-analysis

BRCA2 gene plays an important role in homologous recombination. Polymorphic variants in this gene has been suggested to confer cancer susceptibility. Numerous studies have investigated association between BRCA2 N372H polymorphism and risk of several cancers, especially breast cancer. However, the results were inconsistent. We performed a comprehensive meta-analysis to provide a more precise assessment of the association between N372H and cancer risk, following the latest meta-analysis guidelines (PRISMA). Forty six studies involving 36299 cases and 48483 controls were included in our meta-analysis. The crude ORs and the 95% CIs were used to evaluate the strength of the association. The results indicated that the BRCA2 N372H variant was significantly associated with an increased risk of overall cancer (dominant model: OR = 1.07, 95% CI = 1.01-1.13; recessive model: OR = 1.12, 95% CI = 1.02-1.23). Moreover, stratified analyses by the cancer type and source of control observed significantly increased risk associated with BRCA2 N372H in subgroups with ovarian cancer, non-Hodgkin lymphoma and population-based controls, but not breast cancer or hospital-based controls. We also found such association among Africans. Overall, the meta-analysis suggested that BRCA2 N372H may be a cancer susceptibility polymorphism. Well-designed and large-scale studies are needed to substantiate the association between BRCA2 N372H polymorphism and cancer risk.

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.

Male breast cancer: genetics, epigenetics, and ethical aspects

BACKGROUND AND STUDY DESIGN

Male breast cancer (MBC) is a rare disease compared with female BC and our current understanding regarding breast carcinogenesis in men has been largely extrapolated from the female counterpart. We focus on differences between the ethical issues related to male and female BC patients. A systematic literature search by using PubMed (http://www.ncbi.nlm.nih.gov/pubmed/), was carried out to provide a synopsis of the current research in the field of MBC genetics, epigenetics and ethics. Original articles and reviews published up to September 2012 were selected by using the following search key words to query the PubMed website: 'male breast cancer', 'male breast cancer and genetic susceptibility', 'male breast cancer and epigenetics', 'male breast cancer and methylation', 'male breast cancer and miRNA', 'male breast cancer and ethics'.

RESULTS AND CONCLUSIONS

As in women, three classes of breast cancer genetic susceptibility (high, moderate, and low penetrance) are recognized in men. However, genes involved and their impact do not exactly overlap in female and male BC. Epigenetic alterations are currently scarcely investigated in MBC, however, the different methylation and miRNA expression profiles identified to date in female and male BCs suggest a potential role for epigenetic alterations as diagnostic biomarkers. Overall, much still needs to be learned about MBC and, because of its rarity, the main effort is to develop large consortia for moving forward in understanding MBC and improving the management of MBC patients on a perspective of gender medicine.

Methylenetetrahydrofolate reductase polymorphisms and breast cancer risk in Chinese population: a meta-analysis of 22 case-control studies

The association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and breast cancer risk in the Chinese population has been widely reported, but results were inconsistent. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. Eligible articles were identified through search of databases including Medline, PubMed, Web of Science, Embase, Chinese Biomedical Literature Database (CBM, Chinese), China National Knowledge Infrastructure (CNKI, Chinese), and Wangfang Database (Chinese). The association between the MTHFR polymorphism and breast cancer risk was conducted using odds ratios (ORs) and 95 % confidence intervals (95 % CIs). Finally, a total of 22 studies with 6,103 cases and 7,913 controls were included in our meta-analysis: 13 studies with 3,273 cases and 4,419 controls for C677T polymorphism and 9 studies with 2,830 cases and 3,494 controls for A1298C polymorphism. With regard to C677T polymorphism, significant association was found with breast cancer risk under three models (T vs. C: OR = 1.12, 95 % CI = 1.02-1.23, P = 0.015; TT vs. CC: OR = 1.35, 95 % CI = 1.10-1.67, P = 0.005; TT vs.

CC/CT

OR = 1.37, 95 % CI = 1.11-1.70, P = 0.004). There was no significant association found between A1298C polymorphism and breast cancer risk under all genetic models (C vs. A: OR = 0.96, 95 % CI = 0.89-1.03, P = 0.268; CC vs. AA: OR = 0.98, 95 % CI = 0.77-1.26, P = 0.899; AC vs. AA: OR = 0.95, 95 % CI = 0.88-1.02, P = 0.174; CC vs. AC/AA: OR = 1.00, 95 % CI = 0.78-1.28, P = 0.996, CC/AC vs. AA: OR = 0.96, 95 % CI = 0.89-1.02, P = 0.196). In summary, during this meta-analysis, we found that MTHFR C677T polymorphism was significantly associated with breast cancer risk in the Chinese population. Meanwhile, MTHFR A1298C polymorphism was not associated with breast cancer risk in the Chinese population.

Genetic variation of the brca1 and brca2 genes in macedonian patients

The most significant and well characterized genetic risk factors for breast and/or ovarian cancer are germline mutations in the BRCA1 and BRCA2 genes. The BRCA1 and BRCA2 gene mutations strikingly increase breast cancer risk, suggesting that polymorphisms in these genes are logical candidates in seeking to identify low penetrance susceptibility alleles. The aim of this study was to initiate a screen for BRCA1/2 gene mutations in order to identify the genetic variants in the Republic of Macedonia, and to evaluate the association of several single nucleotide polymorphisms (SNPs) in these genes with breast cancer risk. In this study, we included 100 patients with invasive breast cancer from the Republic of Macedonia, classified according to their family history and 100 controls. The methodology included direct sequencing, single nucleotide primer extension method and multiplex ligation probe amplification (MLPA) analysis, all followed by capillary electrophoresis (CE) on an ABI PRISM™ 3130 Genetic Analyzer. We identified a total of seven carriers of mutations in the BRCA1/2 genes. None of the tested polymorphisms was associated with sporadic breast cancer risk, however, polymorphism rs8176267 in BRCA1 and N372H in BRCA2 showed an association with breast cancer risk in patients with at least one family member with breast cancer.

A comprehensive focus on global spectrum of BRCA1 and BRCA2 mutations in breast cancer

Breast cancer (BC) is the most common cancer of women all over the world. BRCA1 and BRCA2 gene mutations comprise the most important genetic susceptibility of BC. Except for few common mutations, the spectrum of BRCA1 and BRCA2 mutations is heterogeneous in diverse populations. 185AGdel and 5382insC are the most important BRCA1 and BRCA2 alterations which have been encountered in most of the populations. After those Ashkenazi founder mutations, 300T>G also demonstrated sparse frequency in African American and European populations. This review affords quick access to the most frequent alterations among various populations which could be helpful in BRCA screening programs.

Inherited and acquired alterations in development of breast cancer

Breast cancer is the most common cancer among women, accounting for about 30% of all cancers. In contrast, breast cancer is a rare disease in men, accounting for less than 1% of all cancers. Up to 10% of all breast cancers are hereditary forms, caused by inherited germ-line mutations in "high-penetrance," "moderate-penetrance," and "low-penetrance" breast cancer susceptibility genes. The remaining 90% of breast cancers are due to acquired somatic genetic and epigenetic alterations. A heterogeneous set of somatic alterations, including mutations and gene amplification, are reported to be involved in the etiology of breast cancer. Promoter hypermethylation of genes involved in DNA repair and hormone-mediated cell signaling, as well as altered expression of micro RNAs predicted to regulate key breast cancer genes, play an equally important role as genetic factors in development of breast cancer. Elucidation of the inherited and acquired genetic and epigenetic alterations involved in breast cancer may not only clarify molecular pathways involved in the development and progression of breast cancer itself, but may also have an important clinical and therapeutic impact on improving the management of patients with the disease.

Novel sequence variants and common recurrent polymorphisms of BRCA2 in Sri Lankan breast cancer patients and a family with BRCA1 mutations

We previously reported BRCA1 mutations and sequence variants in Sri Lankan breast cancer patients. Mutations and sequence variants of the BRCA2 gene were studied in 149 study participants from the same cohort. There were 55 familial and 54 sporadic breast cancer patients, 20 at-risk individuals and 20 healthy controls. Direct sequencing (exon 11) and sequencing of abnormal bands after screening with single-strand conformation polymorphism (remaining exons) were used to detect mutations and sequence variants. Twenty-three sequence variants were found in the BRCA2 gene. Two novel pathogenic frame-shift additions resulting in a premature stop codon (c.2403 insA/exon 11, c.2667 insT/exon 11) were identified. Possibly pathogenic two novel missense mutations (c.1191 A>C/exon 10, c.5695 A>C/exon 11) one novel intronic variant (IVS15-21 insTT), four novel silent mutations (c.969 C>T/exon 9, c.1353 C>T/exon 10, c.2766 A>C/exon 11 and c.7452 A>G/exon 14) and one novel missense mutation (c.971 C>G/exon 9) were observed. One previously reported possibly pathogenic intronic variant (IVS81 G>C) and several previously reported silent mutations, missense mutations, and one 5' UTR polymorphism were detected. Pathogenic and possibly pathogenic mutations were more frequent in the BRCA2 gene among Sri Lankan familial breast cancer patients when compared to our previous findings for the BRCA1 gene.

Current evidences on XPC polymorphisms and breast cancer susceptibility: a meta-analysis

Published data on the association between three polymorphisms (Lys939Gln, Ala499Val, and PAT±) of Xeroderma Pigmentosum group C (XPC) and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Crude ORs with 95% CIs were used to assess the strength of association between them. A total of 11 studies including 5,090 cases and 5,214 controls were involved in this meta-analysis. For XPC Lys939Gln polymorphism, no obvious associations were found for all genetic models when all studies were pooled into the meta-analysis (Lys/Gln vs. Lys/Lys: OR = 1.00, 95% CI 0.92-1.10; Gln/Gln vs. Lys/Lys: OR = 0.96, 95% CI 0.84-1.09; dominant model: OR = 0.99, 95% CI 0.91-1.08; and recessive model: OR = 0.97, 95% CI 0.86-1.09). In the subgroup analysis by ethnicity or study design, still no obvious associations were found. For XPC Ala499Val polymorphism, also no obvious associations were found for all genetic models when all studies were pooled into the meta-analysis (Val/Ala vs. Ala/Ala: OR = 0.91, 95% CI 0.79-1.05; Val/Val vs. Ala/Ala: OR = 1.07, 95% CI 0.80-1.44; dominant model: OR = 0.93, 95% CI 0.81-1.06; and recessive model: OR = 1.11, 95% CI 0.84-1.48). For XPC PAT± polymorphism, obvious associations were found for recessive model when all studies were pooled into the meta-analysis (OR = 1.41, 95% CI 1.05-1.89). In conclusion, this meta-analysis suggests that the XPC PAT± polymorphism allele may be a low-penetrant risk factor for developing breast cancer.

Current evidences on vascular endothelial growth factor polymorphisms and breast cancer susceptibility

Several polymorphisms of vascular endothelial growth factor (VEGF) such as 936 C/T, -2578 C/A, -406 C/T, and -1154 G/A polymorphism have been identified. Published data on the association between VEGF polymorphisms and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Crude OR with 95% CI was used to assess the strength of association between them. For VEGF 936C/T polymorphism, a total of 10 studies including 7,685 cases and 7,915 controls were involved in this meta-analysis. Overall, no significant associations were found between VEGF 936C/T polymorphism and breast cancer risk when all studies pooled into the meta-analysis (TC vs. CC: OR = 0.904, 95% CI = 0.797-1.024; TT vs. CC: OR = 0.974, 95% CI = 0.786-1.205; dominant model: OR = 0.911, 95% CI = 0.811-1.024; and recessive model: OR = 0.991, 95% CI = 0.801-1.226). In the subgroup analysis by ethnicity, still no significant associations were found for all comparison models. For -2578 C/A, -406 C/T, and -1154 G/A polymorphism, there were too limited data to perform a meta-analysis. In conclusion, this meta-analysis suggests that the VEGF 936C/T polymorphism may be not associated with breast cancer development. However, large sample and representative population-based studies with homogeneous breast cancer patients and well matched controls are warranted to confirm this finding.

Lack of association between methylenetetrahydrofolate reductase gene A1298C polymorphism and breast cancer susceptibility

Published data on the association between methylenetetrahydrofolate reductase gene (MTHFR) A1298C polymorphism and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Medline, PubMed, Embase, and Web of Science were searched. Crude ORs with 95% CIs were used to assess the strength of association between the MTHFR A1298C polymorphism and breast cancer risk. The pooled ORs were performed for co-dominant model (AC vs. AA, CC vs. AA), dominant model (CC+AC vs. AA), and recessive model (CC vs. AC+AA), respectively. A total of 26 studies including 12,244 cases and 15,873 controls were involved in this meta-analysis. Overall, no significant associations were found between MTHFR A1298C polymorphism and breast cancer risk when all studies pooled into the meta-analysis (AC vs. AA: OR=0.99, 95% CI 0.94-1.05; CC vs. AA: OR 0.99, 95% CI 0.90-1.09; dominant model: OR=0.99, 95% CI 0.95-1.04; and recessive model: OR=0.98, 95% CI 0.90-1.08). In the subgroup analysis by ethnicity or study design, still no significant associations were found for all comparison models. In conclusion, this meta-analysis suggests that the MTHFR A1298C polymorphism may be not associated with breast cancer development. However, large sample and representative population-based studies with homogeneous breast cancer patients and well matched controls are warranted to confirm this finding.