Polymorphisms of DNA repair genes and risk of squamous cell carcinoma of the head and neck in young adults

EZH2 Expression in Head-and-Neck Squamous Cell Cancer in Young Patients

EZH2 (Enhancer of zeste homolog 2) promotes tumor growth and survival through numerous mechanisms and is a promising target for novel therapeutic approaches. We aimed to characterize the expression of EZH2 in the tumors of young head-and-neck squamous cell cancer (HNSCC) patients in comparison with the general HNSCC patient population. We used formalin-fixed, paraffin-embedded tissue blocks from 68 random young HNSCC patients (≤39 years, median age: 36 years; diagnosed between 2000 and 2018), which were compared with the samples of 58 age- and gender-matched general HNSCC subjects (median age: 62 years; all diagnosed in the year 2014). EZH2 and p53 expression of the tumors was detected using immunohistochemical staining. Lower EZH2 expression was found to be characteristic of the tumors of young HNSCC patients as opposed to the general population (median EZH2 staining intensity: 1 vs. 1.5 respectively, p < 0.001; median fraction of EZH2 positive tumor cells: 40% vs. 60%, respectively, p = 0.003, Mann-Whitney). Cox analysis identified a more advanced T status (T3-4 vs. T1-2), a positive nodal status, and alcohol consumption, but neither intratumoral EZH2 nor p53 were identified as predictors of mortality in the young patient group. The lower EZH2 expression of young HNSCC patients' tumors discourages speculations of a more malignant phenotype of early-onset tumors and suggests the dominant role of patient characteristics. Furthermore, our results might indicate the possibility of an altered efficacy of the novel anti-EZH2 therapies in this patient subgroup.

Survival association of XRCC1 for patients with head and neck squamous cell carcinoma: A systematic review and meta-analysis

Background: Epidemiologic studies have demonstrated that X-ray repair cross-complementary group 1 (XRCC1) is one of the susceptibility factors in head and neck squamous cell carcinoma (HNSCC) patients. However, its clinical prognostic impact remains controversial. Thus, a meta-analysis was performed to clarify the association between XRCC1 and the survival outcomes in HNSCC patients. Methods: Following the Preferred Reporting Items or Systematic Reviews Meta Analyses (PRISMA) 2020 guidelines, literature searches were systematically performed in PubMed, EMBASE, Web of Science, Wanfang, and Chinese National Knowledge Infrastructure (CNKI) databases with manual retrieval. Hazard ratios (HRs) and 95% confidence intervals (CIs) were collected to estimate the correlation between XRCC1 and the survival outcomes of HNSCC patients. Results: Ten studies including 1995 HNSCC patients who satisfied the inclusion and exclusion criteria were included in this meta-analysis. Pooled analysis indicated that XRCC1 Arg399Gln and XRCC1 high protein expression were significantly correlated with poor overall survival with HR of 1.31 (95% CIs: 1.03-1.66, p = 0.027) and 2.32 (95% CIs: 1.55-3.48 p = 0.000) in HNSCC patients. In addition, our results demonstrated that XRCC1 was significantly associated with poor progression-free survival (HR = 1.42, 95% CIs: 1.15-1.75, p = 0.001) in HNSCC patients. ConclusionThis meta-analysis demonstrated that XRCC1 Arg399Gln and XRCC1 high protein expression increase the risk of poor survival for HNSCC patients. XRCC1 is a potential therapeutic target for HNSCC.

The characteristics of head and neck squamous cell cancer in young adults: A retrospective single-center study

We aimed to characterize clinical and prognostical factors of primary head and neck squamous cell carcinoma (HNSCC) in 85 young patients (≤39 years, median age: 37 years; between 2000-2018) in comparison with 140 institutional general HNSCC patients (median age: 61.5 years). The patient's medical records were collected from the institutional database. The prevalence of smoking and alcohol consumption (65.8% and 48.1%) in the young group exceeded the regional population average but was below the institutional (86.4% and 55%) general HNSCC patient population. Primary tumor sites in the group of young patients were as follows: oral cavity (56.4%), oropharynx (17.6%), hypopharynx (11.7%), and larynx (14.1%). Cumulative five-year overall survival was 44.2% in the young group, but significantly better with early T (T1-2 vs. T3-4: 52.6% vs. 26.7%; p = 0.0058) and N0 status (N0 vs. N+: 65.2% vs. 32.3%; p = 0.0013). Young age, abstinence, earlier stage and laryngeal tumor site might predict a better prognosis. The age distribution and the high prevalence of traditional risk factors among the young patients as well as the predominance of oral cavity tumor localization suggest that the early onset of tumor development could be originated from the premature failure of the intrinsic protective mechanisms.

Gene polymorphisms and risk of head and neck squamous cell carcinoma: a systematic review

Background

Exposure to the same environmental factors in different people have resulted in different susceptibility to head and neck squamous cell carcinoma (HNSCC), which suggests genetic variation may be a risk factor for the development of HNSCC. So, the aim was to review literatures on the association between gene polymorphisms and risk of HNSCCs.

Materials and methods

This systematic review included all articles on the impact of gene polymorphisms on risk and susceptibility to HNSCC published till September 2021 using PubMed, Web of science, SCOPUS, Google Scholar and Cochrane library databases.

Results

Of 1163 initial searched articles, 77 articles were eligible to include in this review. Studies were categorized based on gene functions. In each category, studied gene polymorphisms related to growth control genes, cell cycle control, apoptosis, DNA repair genes, carcinogen-metabolizing enzymes, alcohol-metabolizing genes, antioxidant gene, inflammatory cytokine, transcription factor, tumor immunity, folate metabolism, and tumor suppressor gene were discussed separately. Among the polymorphisms that are often significantly associated with HNSCC risk are: GSTM1 null, GSTT1 null, CYP2D6 *4, XRCC1 Arg194Trp and Arg399Gln, ERCC1 C8092A, XPD Lys751Gln, XRCC3 Thr241Met, P53 codon 72 and MTHFR C677T polymorphisms.

Conclusion

Varied and contradictory results have been reported in different studies regarding the association of gene polymorphisms with HNSCC risk. To conclude about this association and to overcome these contradictions, it is necessary to use the results of existing meta-analyses or to perform new or updated meta-analyses.

The Association Between the XRCC1 Arg399Gln Polymorphism and the Risk of Head and Neck Cancer: An Updated Meta-Analysis Including 14586 Subjects

BACKGROUND

Accumulated evidence shows that DNA repair gene X-ray repair cross complementing group 1 (XRCC1) may determine individual susceptibility to head and neck cancer (HNC) as a major DNA repair gene. However, the results from previous studies have been conflictive and inconsistent. In order to more accurately estimate and integrate the association between XRCC1 Arg399Gln polymorphism and HNC risk, we conducted a meta-analysis including 14586 subjects.

METHODS

In this meta-analysis, literatures were collected up until September 15, 2020 through multifarious retrieval strategies by searching through electronic databases of PubMed, Cochrane Library, EMBASE, Medline, Web of Science and CNKI. The association between the XRCC1 Arg399Gln polymorphism and HNC was analyzed through calculating summary odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Thirty-one studies consisting of 6025 cases and 8561 controls were identified and analyzed. No significant association between XRCC1 Arg399Gln polymorphisms and HNC risk was found under the allelic (OR = 0.94, 95% CI: 0.82-1.07, P = 0.35), homozygous (OR = 0.99, 95% CI: 0.81-1.21, P = 0.91), heterozygous (OR = 1.01, 95% CI: 0.90-1.13, P = 0.91), dominant (OR = 1.05, 95% CI: 0.85-1.29, P = 0.67) or recessive (OR = 0.93, 95% CI: 0.80-1.08, P = 0.35) genetic models in the overall comparison. In addition, subgroup analyses according to tumor site also displayed no significant association between XRCC1 Arg399Gln polymorphisms and HNC risk. However, subgroup analyses based on ethnicity indicated that HNC risk was significantly related to Arg399Gln genetic heterozygous model (OR = 1.21, 95%CI: 1.04-1.42, P = 0.02) and dominant model (OR = 1.27, 95%CI: 1.02-1.60, P = 0.04) in Caucasians populations.

CONCLUSION

The results from this meta-analysis suggest that the XRCC1 Arg399Gln variants (Arg/Gln and Arg/Arg+Arg/Gln) may contribute to high HNC risk among Caucasians. Further well-designed studies and larger sample sizes are needed to validate our findings.

DNA repair, NFKβ, and TP53 polymorphisms associated with potentially malignant disorders and oral squamous cell carcinoma in Argentine patients

OBJECTIVE

An important strategy in cancer prevention is to identify individual susceptibilities for cancer development through the genomic profile. Developing countries such as Argentina have no data on genetic composition. The aim of this study was to evaluate the single nucleotide polymorphisms of genes related to DNA repair (XCCR3, XPD), cell cycle arrest/apoptosis (TP53), and inflammation (NFKβ) of patients with precancer and oral cancer and to contribute to recognizing potential risk of developing these pathologies, and incorporate the risk patients into a clinical follow-up program in Córdoba, Argentina.

STUDY DESIGN

A cross-sectional study was performed on 140 patients with oral squamous cell carcinoma (OSCC), oral potentially malignant disorders (OPMDs), and controls. Genotyping of single nucleotide polymorphisms was performed using allele-specific polymerase chain reaction or restriction fragment length polymorphism techniques. The variables were evaluated by bivariate and multivariate statistical methods, with P < .05 statistically significant.

RESULTS

The multiple correspondence analyses showed that patients with OSCC are clustered with the T allele of XRCC3 T241 M and the C allele of TP53 R72 P, and patients with OPMDs are clustered with the T allele of NFKβ-519.

CONCLUSION

Our preliminary results showed that the C allele of the Pro72 variant of TP53 was related to OSSC and OPMD, and the T allele of NFKβ-519 is related to OPMDs in Argentine patients.

Association of nineteen polymorphisms from seven DNA repair genes and the risk for bladder cancer in Gansu province of China

Background

Balance of DNA damage and proper repair plays an important role in progression of bladder cancer. Here we aimed to assess the associations of nineteen polymorphisms from seven DNA repair–associated genes (PRAP1, OGG1, APEX1, MUTYH, XRCC1, XRCC2 and XRCC3) with bladder cancer and their interactions in the disease in a Han Chinese population.

Methodology/Principal Findings

A chip-based TaqMan genotyping for the candidate genes was performed on 227 bladder cancer patients and 260 healthy controls. APEX1 rs3136817, MUTYH rs3219493, three SNPs (rs3213356, rs25487 and rs1799782) in XRCC1, and three SNPs (rs1799794, rs861531 and rs861530) in XRCC3 showed significant associations with the risk of bladder cancer. In haplotype analysis, elevated risks of bladder cancer were observed in those with either haplotype GT (OR = 1.56, P = 0.003) of APEX1, or GGGTC (OR = 2.05, P = 0.002) of XRCC1, whereas decreased risks were in individuals with either GCGCC (OR = 0.40, P = 0.001), or GCGTT (OR = 0.60, = 0.005) of XRCC1, or CCC (OR = 0.65, P = 0.004) of MUTYH, or TTTAT (OR = 0.36, P = 0.009) of XRCC3. Interaction analysis showed that the two-loci model (rs1799794 and rs861530) was the best with the maximal testing accuracy of 0.701, and the maximal 100% cross-validation consistency (P = 0.001).

Conclusions

Polymorphisms and haplotypes of DNA repair genes are associated with the risk of bladder cancer, and of which the SNPs (rs1799794 and rs861530) in XRCC3 gene might be two major loci in relation to the susceptibility to bladder cancer in a northwest Chinese population.

A Comparison of Clinicopathological Differences in Oral Squamous Cell Carcinoma in Patients Below and Above 40 Years of Age

Introduction

Recent times have revealed an increase in incidence of Oral Squamous Cell Carcinoma (OSCC) in young adults including those who lack association with typical risk factors such as tobacco. There are reported variations in clinical behaviour of tumours in young and older individuals.

Aim

Present study evaluated differences in clinicopathological characteristics between two groups of OSCC, below and above 40 years of age.

Materials and Methods

An analytical study was performed on two groups of OSCC patients, below and above 40 years of age. Clinicopathological parameters of site distribution, type of habit, histological grade, nodal metastasis, margin status, mitotic index and Argyrophilic Nucleolar Organizing Regions (AgNOR) count were compared. Chi-square test and Students t- test were applied for statistical analysis.

Results

Present study revealed that mean AgNOR count was significantly higher in older group (6.38) than younger group (4.27). However, no significant differences were noted in site distribution, tobacco habit, histological grade, mitotic index, nodal metastasis and status of resected surgical margins between the two age groups. A trend for increased metastasis and poor histological differentiation was also observed in the older and younger age group respectively. Most common site was buccal mucosa followed by tongue in both groups.

Conclusion

Reasons for documented variability in tumour characteristics between young and older patients are currently unclear. Difference in AgNOR count found in present study is suggestive of variability in proliferative and ploidy characteristics between different age groups and supports the hypothesis of genetic and epigenetic influences in development of oral cancer.

Global incidence of oral and oropharynx cancer in patients younger than 45 years versus older patients: A systematic review

Head and neck squamous cell carcinoma (HNSCC) is typically regarded as a disease of elderly people. However, increasing numbers of patients worldwide with HNSCC at younger age (defined as <45 years old) have been reported in recent years. To assess geographical variations and trends worldwide in incidence of oral and oropharyngeal cancer in young patients, a systematic review was conducted in PubMed and Google scholar databases from 1975 to June 2016. Seventy-eight studies were selected for further study. Nineteen population-based studies on incidence rate were available from 13 countries, showing a prominent increase over time except for the Netherlands. A notable rise of oral (mobile) tongue cancer among white women and oropharyngeal cancer in white men was observed. Data suggest that cancer in young patients may be a distinct clinical entity and characterised by different aetiology and pathogenesis. Additionally, the relative proportion of oral and oropharyngeal cancer in young patients to total incidence revealed a significant difference between estimates from North America (5.5%) and both Africa (17.2%) and Middle East (14.5%). It is concluded that (i) a rising trend in oral and oropharynx cancers is observed in young patients worldwide; (ii) incidence studies should properly define outcomes in age cohorts and use a consensus cut-off for young patients; (iii) more population-based studies should be performed in non-Western regions to get accurate global measures of incidence for these cancers in young subpopulations and (iv) there is an urge to identify new aetiological factors in these young patients.

Increased expression of ERCC2 gene in head and neck cancer is associated with aggressive tumors: a systematic review and case-control study

INTRODUCTION

The excision repair cross-complementation group 2 (ERCC2) ATP-dependent helicase is an essential member of the DNA repair pathway. It has been observed to be differentially expressed in different cancers, which shows its involvement in carcinogenesis.

AIM

In the present study we have tried to determine the association of expression patterns of this gene with head and neck carcinogenesis.

METHOD

We first carried out a systematic review of the available studies on the role of ERCC2 in head and neck cancer (HNC). In order to test the hypothesis that the expression patterns of XPD/ERCC2 play a critical role in HNC pathogenesis, we then conducted a population based case-control study on 81 head and neck tumor samples and adjacent normal-tissue control samples. Reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative polymerase chain reaction (qPCR) were used to assess ERCC2 deregulation at the mRNA level.

RESULT

Expression analysis showed that the ERCC2 expression level was significantly upregulated (p<0.05) in HNC tissues compared with adjacent normal tissues. Furthermore, the expression pattern of ERCC2 was correlated with the expression pattern of Ki-67 and a significant correlation (r = 0.230, p<0.03) was observed between ERCC2 and Ki-67. Spearman's correlation also showed a significant correlation between ERCC2 expression and tumor stage (r = 0.271, p<0.02) and grade (r = 0.228, p<0.02) of HNC.

CONCLUSIONS

Our data suggest that deregulation of ERCC2 in HNC has the potential to predict a more aggressive cancer phenotype and may be considered a possible biomarker for improved diagnosis and prognosis of HNC.

DNA repair genes XRCC1 and ERCC1 polymorphisms and the risk of sporadic breast cancer in Han women in the Gansu Province of China

AIMS

Polymorphisms in DNA damage repair genes may affect DNA repair capacity and modulate breast cancer susceptibility. In this study, we aimed to analyze two polymorphisms for each of the DNA repair genes X-ray repair cross-complementing group 1 (XRCC1) rs25487 and rs1799782 and excision repair cross-complementing group 1 (ERCC1) rs3212964 and rs11615, to evaluate their associations with the risk of sporadic breast cancer in Han women in the Gansu Province of China.

METHODS

Genotypes were determined by a polymerase chain reaction-based approach for 101 patients with breast cancer and in 101 disease-free controls.

RESULTS

We found that individuals with the AA genotype at XRCC1 rs25487 had a significantly increased risk of breast cancer compared with GG genotype (p<0.001, odds ratio [OR]=6.39, 95% confidence interval [CI]: 2.18-18.65). The dominant model showed that the combined rs25487 genotypes (AA+AG) increased the disease risk (p<0.001, OR=3.17, 95% CI: 1.76-5.72). However, no statistical associations were found between rs1799782 in XRCC1, or rs3212964 and rs11615 in ERCC1 and the risk of disease. In haplotype analysis, the GC haplotype in XRCC1 conferred an increased risk (p<0.001) with a 4.78-fold increase for each copy (95% CI: 2.52-8.72). Significant associations were also shown between the single nucleotide polymorphisms (SNPs) and the status of estrogen receptor (ER), progesterone receptor (PR), and HER-2.

CONCLUSIONS

The results suggest that the XRCC1 rs25487 polymorphism may increase the risk of breast cancer.

Combined effect of tobacco and DNA repair genes polymorphisms of XRCC1 and XRCC2 influence high risk of head and neck squamous cell carcinoma in northeast Indian population

Tobacco consumption in various forms is one of the major risk factor for the development of head and neck squamous cell carcinoma. Polymorphisms in XRCC1 and XRCC2 genes may alter an individual's susceptibility to tobacco-related cancers. Here, we have investigated the interaction of XRCC1 (Arg399Gln) and XRCC2 (Arg188His) polymorphism and tobacco exposure in the progression of HNSCC in northeast Indian population. The population-based case-control study includes 110 HNSCC patients and 140 controls. The polymorphisms of XRCC1 and XRCC2 were studied by means of PCR-RFLP, and the results were confirmed by DNA sequencing. Smokers and tobacco-betel quid chewers were significantly higher in cases (P = 0.045 and 0.033). The variant homozygote AA genotype of XRCC1 Arg399Gln and heterozygote GA genotype of XRCC2 Arg188His has an increased risk toward HNSCC (OR 2.43; P = 0.031 and OR 3.29; P < 0.01, respectively). The interaction between tobacco-betel quid chewing and variant genotypes of XRCC1 and XRCC2 resulted in several fold increase the risk of HNSCC, when compared to non-chewers. Heavy smokers carrying XRCC1 AA and XRCC2 GA genotypes had a significantly higher risk of HNSCC compared to never smokers (P = 0.017 and 0.003, respectively). Upon gene-gene interaction analysis, individuals carrying both XRCC1 GA (Arg/Gln) and XRCC2 GA (Arg/His) genotypes had the highest risk of HNSCC (P = 0.001).Our finding suggests that interaction of tobacco and polymorphisms of XRCC1 and XRCC2 increases the risk of HNSCC. Furthermore, cross talk between these two DNA repair genes might modulate susceptibility toward HNSCC.

Association between the XRCC1 Arg399Gln polymorphism and head and neck cancer susceptibility: a meta-analysis based on case-control studies

Published data regarding the association between the XRCC1 Arg399Gln polymorphism and head and neck cancer (HNC) susceptibility showed inconsistent results. This meta-analysis of eligible literatures was performed to draw a more precise estimation of the relationship. We systematically searched PubMed, Embase, and Web of Science with a time limit of Oct 28, 2013. Summary odds ratios (ORs) with 95% CIs were used to assess the strength of association between XRCC1 Arg399Gln polymorphism and HNC susceptibility using random-effect model. A total of 27 case-control studies including 5942 cases and 9041 controls were included for analysis. Meta-analysis of total studies showed that the XRCC1 Arg399Gln variant carriers were not susceptible to HNC (AA vs. GG: OR=0.92, 95% CI=0.77-1.11; AG vs. GG: OR=1.05, 95% CI=0.76-1.44; the dominant model AA+AG vs. GG: OR=1.00, 95% CI=0.78-1.29; the recessive model AA vs. AG+GG: OR=0.91, 95% CI=0.71-1.16). Further, subgroup analyses by ethnicity and source of controls did not identify any significant associations of XRCC1 Arg399Gln polymorphism with head and neck susceptibility in any populations. Our meta-analysis suggested that the XRCC1 Arg399Gln polymorphism was not a risk factor for HNC susceptibility.

Association of X-ray repair cross-complementing group 1 Arg194Trp, Arg399Gln and Arg280His polymorphisms with head and neck cancer susceptibility: a meta-analysis

Background

Previous studies on the association of X-ray repair cross-complementing group 1 (XRCC1) Arg194Trp, Arg399Gln, and Arg280His polymorphisms with head and neck cancer (HNC) have produced inconsistent results. The aim of the present study was to evaluate the effects of these three polymorphic variants on HNC risk.

Methods

The PubMed and EMBASE databases were searched for genetic association studies on the XRCC1 Arg194Trp, Arg399Gln, and Arg280His polymorphisms and HNC risk. (The most recent search was conducted on 20 August, 2013.) Twenty-six studies were identified and meta-analysis was performed to evaluate the association between the polymorphism and HNC by calculating combined odds ratios and 95% confidence intervals.

Results

No significant association was found under the allelic, homozygous, heterozygote, and dominant genetic models in the overall comparison. Further, no significant association between the XRCC1 Arg399Gln and Arg280His polymorphisms and HNC risk was detected under the four genetic models in subgroup analyses based on ethnicity, cancer site, and whether or not the studies had been adjusted for cigarette smoking and alcohol. However, in stratified analyses based on cancer site, a significant association was found between the XRCC1 Arg194Trp polymorphism and oral cancer under the allelic, heterozygote, and dominant models. The XRCC1 Arg194Trp polymorphism was significantly associated with HNC risk in studies that were adjusted for smoking and alcohol under the homozygous and heterozygote models.

Conclusion

The meta-analysis results suggest that the XRCC1 Arg399Gln and Arg280His polymorphisms are probably not associated with the risk of HNC, but the XRCC1 Arg194Trp polymorphism was associated with increased risk of HNC in the subgroup analysis of studies adjusted for smoking and alcohol and with increased risk of oral cancer in the stratified analyses based on cancer site. Further studies with larger samples are needed to confirm these findings.

Oral cavity and oropharyngeal squamous cell carcinoma in young adults: a review of the literature

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a disease of middle-aged to elderly adults. However, an increased incidence of HNSCC in young people under 45 years of age has been reported recently. In the present review, we focused on the epidemiology and aetiology of HNSCC in adults under 45 years of age.

METHODS

We reviewed literature related to HNSCC in adult patients less than 45 years of age and discussed current treatment options and prognosis.

RESULTS

HNSCC in young adults is associated with a higher incidence rate in nonsmokers, lower female-to-male ratio, a higher percentage of oral cavity and oropharynx tumours, and fewer second primary tumours. However, aside from traditional risk factors of tobacco and alcohol exposure, the causes of these cancers in young adults remain unclear. Agents that might contribute to risk include infection with high-risk human papillomavirus subtypes as well as genetic factors or immunodeficiency status. The expected increase in incidence and mortality of the young with HNSCC may become a major public health concern if current trends persist, particularly lifestyle habits that may contribute to this disease.

CONCLUSIONS

Given the younger age and potential long-term adverse sequelae of traditional HNSCC treatments, young adults should be treated on a case-by-case basis and post-therapy quality of life must be considered in any treatment-decision making process.

Association of X-ray repair cross complementing group 1 Arg399Gln polymorphisms with the risk of squamous cell carcinoma of the head and neck: evidence from an updated meta-analysis

BACKGROUND

Epidemiologic studies have reported the association of X-ray repair cross-complementary group 1 (XRCC1) Arg399Gln polymorphisms with susceptibility to squamous cell carcinoma of the head and neck (HNSCC). However, the results were conflictive rather than conclusive. The purpose of this study was to clarify the association of XRCC1 Arg399Gln variants with HNSCC risk.

METHODS

Systematic searches were performed through the search engines of PubMed, Elsevier, Science Direct, CNKI and Chinese Biomedical Literature Database. Summary odds ratio (OR) with 95% confidence intervals (CI) was computed to estimate the strength association.

RESULTS

Overall, we did not observe any association of XRCC1 Arg399Gln polymorphisms with HNSCC risk in total population (OR = 0.95, 95% CI: 0.76-1.19 for Gln/Gln vs. Arg/Arg, OR = 1.05, 95% CI: 0.92-1.20 for Arg/Gln vs. Arg/Arg, and OR = 1.03, 95% CI: 0.90-1.18 for Gln/Gln+Arg/Gln vs. Arg/Arg) based on 18 studies including 3917 cases and 4560 controls. In subgroup analyses, we observed an increased risk of XRCC1 399 Arg/Gln genotype for HNSCC in Caucasians (OR = 1.20, 95% CI: 1.00-1.44) and Gln/Gln genotype for larynx squamous cell carcinoma (OR = 1.63, 95% CI: 1.10-2.40). We did not observe any association between XRCC1 Arg399Gln variants and HNSCC risk in additional subgroup analyses.

CONCLUSION

The results from this present meta-analysis suggest that XRCC1 Arg399Gln variants may contribute to HNSCC risk among Caucasians and to the risk of larynx squamous cell carcinoma. Further, well-designed studies with larger sample sizes are required to verify our findings.

DNA repair gene XRCC1 polymorphisms and head and neck cancer risk: an updated meta-analysis including 16344 subjects

BACKGROUND

DNA repair gene X-ray repair cross complementing group 1 (XRCC1) plays an important role in the maintenance of the genomic integrity and protection of cells from DNA damage. Sequence variation in XRCC1 gene may alter head and neck cancer (HNC) susceptibility. However, these results are inconclusive. To derive a more precise estimation of the relationship between XRCC1 polymorphism and HNC risk, we undertook a meta-analysis involving 16,344 subjects.

METHODS

A search of the literature by PubMed, Embase, Web of Science and China National Knowledge Infrastructure was performed to identify studies based on the predetermined inclusion criteria. The odds ratio (OR) with 95% confidence interval (CI) was combined using a random-effects model or a fixed-effects model.

RESULTS

Twenty-nine studies consisting of 6,719 cases and 9,627 controls were identified and analyzed. Overall, no evidence of significant association was observed between XRCC1 Arg194Trp, XRCC1 Arg280His, XRCC1 Arg399Gln genotypes and the risk of HNC in any genetic models. Subgroup analyses according to ethnicity, tumor site, publication year, genotyping method also detected no significant association in any subgroup, except that oral cancer was associated with Arg194Trp variant in recessive model. Furthermore, no significant effect of these polymorphisms interacted with smoking on HNC risk was detected but Arg194Trp homozygous variant.

CONCLUSION

In conclusion, this meta-analysis suggests that the XRCC1 Arg194Trp, Arg280His and Arg399Gln polymorphism may not involve in HNC susceptibility. Further studies about gene-gene and gene-environment interactions in different populations are required.

DNA repair gene polymorphisms and risk of head and neck cancer in the Tunisian population

Altered activity of DNA repair enzymes may be involved in modulating cancer susceptibility and pathogenesis of head and neck cancer (HNC). We conducted a case-control study to test the association between three common single-nucleotide polymorphisms of XRCC1, ERCC2, and ERCC3 genes with HNC risk in Tunisian patients. To the best of our knowle dge, this is the first report on polymorphisms in XRCC1, ERCC2, and ERCC3 and susceptibility to HNC in our population. The genotype analyses of XRCC1 Arg399Gln, ERCC2 Lys751Gln, and ERCC3 7122 A>G polymorphisms for 169 HNC patients, and 261 controls were performed using the PCR-based restriction fragment length polymorphism. Stratification of the populations according to smoking and drinking habits and occupational exposure highlighted the importance of tobacco, alcohol, and toxic substance as three risk co-factors for the development of HNC. Our study suggests that only the XRCC1 Arg399Gln polymorphism was associated with the risk of HNC in the Tunisian population (OR = 2.04; P = 0.001). Furthermore, the risk of HNC was associated with XRCC1 Arg399Gln polymorphism stratified by occupational exposure status (OR = 2.29; P = 0.024). However, no statistically significant association was observed between the risk of developing HNC and the ERCC2 Lys751Gln and ERCC3 A>G polymorphisms. These data suggest that the XRCC1 Arg399Gln polymorphism is associated with an increased risk of developing HNC, because it correlates with occupational exposure in Tunisian population.

Single-nucleotide polymorphisms in nucleotide excision repair genes, cigarette smoking, and the risk of head and neck cancer

BACKGROUND

Cigarette smoking is associated with increased head and neck cancer (HNC) risk. Tobacco-related carcinogens are known to cause bulky DNA adducts. Nucleotide excision repair (NER) genes encode enzymes that remove adducts and may be independently associated with HNC, as well as modifiers of the association between smoking and HNC.

METHODS

Using population-based case-control data from the Carolina Head and Neck Cancer Epidemiology (CHANCE) Study (1,227 cases and 1,325 controls), race-stratified (White, African American), conventional, and hierarchical logistic regression models were used to estimate ORs with 95% intervals (I) for the independent and joint effects of cigarette smoking and 84 single-nucleotide polymorphisms (SNP) from 15 NER genes on HNC risk.

RESULTS

The odds of HNC were elevated among ever cigarette smokers and increased with smoking duration and frequency. Among Whites, rs4150403 on ERCC3 was associated with increased HNC odds (AA+AG vs. GG; OR, 1.28; 95% CI, 1.01-1.61). Among African Americans, rs4253132 on ERCC6 was associated with decreased HNC odds (CC+CT vs. TT; OR, 0.62; 95% CI, 0.45-0.86). Interactions between ever cigarette smoking and three SNPs (rs4253132 on ERCC6, rs2291120 on DDB2, and rs744154 on ERCC4) suggested possible departures from additivity among Whites.

CONCLUSIONS

We did not find associations between some previously studied NER variants and HNC. We did identify new associations between two SNPs and HNC and three suggestive cigarette-SNP interactions to consider in future studies.

IMPACT

We conducted one of the most comprehensive evaluations of NER variants, identifying a few SNPs from biologically plausible candidate genes associated with HNC and possibly interacting with cigarette smoking.

Association between the XRCC3 T241M polymorphism and risk of cancer: evidence from 157 case-control studies

The T241M polymorphism in the X-ray cross-complementing group 3 (XRCC3) had been implicated in cancer susceptibility. The previous published data on the association between XRCC3 T241M polymorphism and cancer risk remained controversial. Hence, we performed a meta-analysis to investigate the association between cancer susceptibility and XRCC3 T241M (61,861 cases and 84,584 controls from 157 studies) polymorphism in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly increased cancer risk was observed in any genetic model (dominant model: odds ration [OR]=1.07, 95% confidence interval [CI]=1.00-1.13; recessive model: OR=1.15, 95% CI=1.08-1.23; additive model: OR=1.17, 95% CI=1.08-1.28) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, the elevated risk remained for subgroups of bladder cancer and breast cancer, especially in Caucasians. In addition, significantly decreased lung cancer risk was also observed. In summary, this meta-analysis suggests the participation of XRCC3 T241M in the susceptibility for bladder cancer and breast cancer, especially in Caucasians, and XRCC3 T241M polymorphism is associated with decreased lung cancer risk. Moreover, our work also points out the importance of new studies for T241M association in some cancer types, such as gastric cancer, colorectal cancer, and melanoma skin cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the XRCC3 polymorphism in cancer development.