Evaluation of glutathione S-transferase polymorphisms and mutagen sensitivity as risk factors for the development of second primary tumors in patients previously diagnosed with early-stage head and neck cancer

Mutagen sensitivity and risk of second cancer in younger adults with head and neck squamous cell cancer: 15-year results

Purpose

To evaluate the mutagen sensitivity phenotype on the risk of second primary cancer (SPC) in patients with head and neck squamous cell carcinoma (HNSCC), and to estimate the long-term rate of SPC and the outcome with SPC.

Methods

A survey was made regarding SPC among 124 younger (≤ 50 years) adults with HNSCC who were enrolled in a pretreatment mutagen sensitivity investigation during 1996–2006. Mutagen sensitivity was assessed by exposing lymphocytes to bleomycin in vitro and quantifying the bleomycin-induced chromatid breaks per cell (b/c). Patients were classified as hypersensitive (> 1 b/c) or not hypersensitive (≤ 1 b/c).

Results

Mean follow-up time for all patients was 68 months (range: 5–288 months), and the 15-year cancer-specific survival was 15%. Twenty patients (16%) developed a SPC (15-year estimated rate: 41%), and half of them was hypersensitive. The crude rate of SPC for hypersensitive (n = 65) or not hypersensitive (n = 59) patients were 15 and 17%, respectively (p = 0.4272). The 15-year estimated rate of SPC for hypersensitive and not hypersensitive patients was 36 and 48%, respectively (p = 0.3743). Gender, UICC stages, anatomical sites of index cancer did not prove to be a significant risk factor for SPC. Forty-five percent of SPC developed after the 10-year follow-up. The 3‑year cancer-specific survival was 23% with SPC.

Conclusion

According to our findings, mutagen hypersensitivity was not associated with an increased SPC risk in HNSCC patients. Patients are at a lifelong risk of developing a SPC. Survival with SPC is very poor.

Single nucleotide polymorphisms and the risk of developing a second primary cancer among head and neck cancer patients: a systematic literature review and meta-analysis

BACKGROUND

Head and Neck Cancer (HNC) survivors are at increased risk of developing a second primary cancer (SPC). Along with the environmental risk factors, genetic factors have been associated with a potential increased susceptibility to SPC development. We aim to identify the Single Nucleotide Polymorphisms (SNPs) that contribute to SPC development among HNC survivors through a systematic review and meta-analysis.

METHODS

We searched PubMed, Scopus and ISI Web of Science for eligible studies published in English until January 31st, 2020. We included studies reporting primary data that evaluated the association between SNPs and SPC risk in HNC patients. Data were pooled in a random-effect meta-analyses, when at least two studies on the same SNP evaluated the same genotype model. Heterogeneity was assessed using the χ2-based Q-statistics and the I2 statistics. Quality of the included studies was assessed using the Q-Genie tool.

RESULTS

Twenty-one studies, of moderate to good quality, were included in the systematic review. Fifty-one genes were reported across the included studies to have significant associations with an increased SPC risk. Overall, 81 out of 122 investigated SNPs were significantly associated with the SPC risk. Seven studies were included in the meta-analysis, which showed five SNPs associated with an increased risk of SPC: p21C70T, CT + TT (HR = 1.76; 95% CI: 1.28-2.43); FASLG -844C > T, CT + TT (HR = 1.82; 95% CI: 1.35-2.46), P21 C98A, CA + AA (HR = 1.75; 95% CI: 1.28-2.38); FAS -670A > G (HR = 1.84; 95% CI: 1.28-2.66) and GST-M1, Null genotype (HR = 1.54; 95% CI: 1.13-2.10).

CONCLUSIONS

The identified SNPs in our systematic review and meta-analysis might serve as potential markers for identification of patients at high risk of developing SPC after primary HNC.

PROSPERO REGISTRATION NUMBER

CRD42019135612 .

Susceptibility of Multiple Primary Cancers in Patients With Head and Neck Cancer: Nature or Nurture?

Multiple primary cancers (MPCs) are major obstacles to long-term survival in head and neck cancer (HNSCC), however, the molecular mechanism underlying multiple carcinogenesis remains unclear. “Field cancerization” is a classical theory to elaborate the malignant progression of MPCs. Apart from environmental and immune factors, genetic factors may have great potential as molecular markers for MPCs risk prediction. This review focuses on inherited and acquired gene mutations in MPCs, including germ-line mutation, single-nucleotide polymorphism, chromosomal instability, microsatellite instability and DNA methylation. And definition and prognosis of MPCs have also been discussed. These may pave the way for the early detection, prevention and effective treatment of MPCs in HNSCC.

GTSP1 expression in non-smoker and non-drinker patients with squamous cell carcinoma of the head and neck

Introduction

The main risk factors for head and neck squamous cell carcinoma (HNSCC) are tobacco and alcohol consumption and human papillomavirus (HPV) infection. However, in a subset of patients, no risk factors can be identified. Glutathione S-transferase π (GTSP1) is a carcinogen-detoxifying enzyme that is activated by exposure to carcinogens, and it is associated with a reduction in response to toxic therapies. We studied the expression of GTSP1 in tumor and non-tumor tissue samples from patients with and without these risks to identify whether GTSP1 expression differs according to exposure to carcinogens.

Materials and methods

Non-smoker/non-drinker (NSND) and smoker/drinker (SD) patients were matched according to age, gender, tumor site, TNM stage, grade and histological variants to establish 47 pairs of patients who have been previously tested for HPV. GTSP1 immunostaining was analyzed using a semi-quantitative method with scores ranging from 0 to 3 according to the area of immunostaining.

Results

GTSP1 expression was detected in the tumors of both groups. GTSP1 expression was higher in the non-tumor margins of SD patients (p = 0.004). There was no association between GTSP1 expression and positivity for HPV. No differences in survival were observed according to GTSP1 staining in tumors and non-tumor margins.

Conclusion

This study showed that GTSP1 was expressed in tumors of HNSCC patients regardless of smoking, drinking or HPV infection status. The difference in GTSP1 expression in non-tumor margins between the two groups may have been due to two possible reasons. First, elevated GTSP1 expression in SD patients might be the result of activation of GTSP1 in response to exposure to carcinogens. Second, alternatively, impairment in the detoxifying system of GTSP1, as observed by the reduced expression of GTSP1, might make patients susceptible to carcinogens other than tobacco and alcohol, which may be the underlying mechanism of carcinogenesis in the absence of risk factors.

Site disparities in apoptotic variants as predictors of risk for second primary malignancy in patients with squamous cell carcinoma of the head and neck

Background

FAS/FASL promoter variants are considered in altering transcriptional activity of those genes and consequently alter regulation of cell death. However, no studies have investigated whether tumor sites contribute to the association between FAS/FASL polymorphisms and risk for second primary malignancy (SPM).

Method

In this study, FAS670 A > G, FAS1377 G > A, FASL124 A > G, and FASL844C > T polymorphisms were genotyped in 752 OPC and 777 non-OPC patients. Both univariate and multivariable cox proportional hazard models were used to assess the associations.

Results

The univariate and multivariable analyses showed that patients with index OPC and FASL844 CT/TT genotype had significantly increased risk of SPM (cHR, 2.5; 95 % CI, 1.1–5.8, P = 0.043 and aHR, 2.7; 95 % CI, 1.2–6.0, P = 0.032) compared with those with FASL844 CC genotype as the reference group, while index non-OPC patients with FAS670 AG/GG and FasL844 CT/TT genotypes had significantly increased risk of SPM (cHR, 2.2 and 1.8; 95 % CI, 1.2–5.7 and 1.1–3.2; and P = 0.04 and 0.041, respectively and aHR, 2.4 and 1.7; 95 % CI, 1.1–5.1 and 1.0-3.0; and P = 0.043 and 0.049, respectively) compared with their corresponding AA and CC genotypes . Moreover, patients carrying more FAS/FASL variants significantly increased risk of SPM among index non-OPC patients. The stratified analysis showed that smoking status differently modified the associations between FAS/FASL polymorphisms and risk of SPM among index non-OPC from OPC patients.

Conclusion

These results suggested that FAS/FASL polymorphisms might significantly modify SPM risk among patients with SCCHN in a tumor site-specific manner.

The impact of GSTM1/GSTT1 polymorphism for the risk of oral cancer

OBJECTIVES

Since development of oral squamous cell cancer (OSCC) is triggered by various noxa, different variants of the antioxidant glutathione S-transferases (GSTs) can counteract toxic compounds (e.g., tobacco smoke). Because different polymorphisms of GST are known to have an increased sensitivity to carcinogenic agents, the aim of this study was to analyze whether GSTM1 or GSTT1 polymorphisms increase the risk for the development of OSCC.

MATERIALS AND METHODS

GSTM1 and GSTT1 polymorphism was examined in healthy volunteers (n = 93) and in patients with OSCC (n = 100) by PCR after brush biopsy of oral mucosa. Odds ratio (OR) was calculated to evaluate the risk of oral cancer development.

RESULTS

GSTM1 and GSTT1 deletion was found in 57% (53/93) and 18% (17/93), respectively, in healthy patients, while the OSCC group showed 57% (57/100) for GSTM1 deletion and 22% (22/100) with a deletion of GSTT1. Odds ratio for GSTM1 polymorphism was 1.00 and for GSTT1 1.26. Comparing smokers and nonsmokers with GSTM1 deletion polymorphism, OR was 4.35, while smokers without GSTM1 deletion showed an OR of 1.45. Adapting these data to the smoking habits of the general population in Germany, the OR was 9.25 for smokers with a GSTM1 deletion and OR 6.68 for smokers without a GSTM1 deletion. In smokers with GSTT1 deletion polymorphism, OR was 1.6 (adapted to the smoking habits of the general population: OR 6.16) and 3.16 (OR 8.56) in smokers without deletion in GSTT1 gene.

CONCLUSIONS

Analysis of GST-M1 polymorphism in smokers could help to identify patients with a higher risk for the development of oral cancer.

CLINICAL RELEVANCE

Early detection of OSCC due to a close meshed monitoring program for patients with GST-M1 polymorphism could help to improve the patient outcome. For polymorphism investigations, the oral brush biopsy is a sufficient method to gain DNA material.

Mucoepidermoid carcinoma of the parotid as a secondary malignancy after chemotherapy in a child with neuroblastoma

Secondary neoplasms are not reported frequently after neuroblastoma, which until recently was a cancer with limited long-term survival. Although salivary gland tumors in children and adolescents may be idiopathic, they are seen more often after head and neck radiation. We report a child with stage 4 neuroblastoma treated with high-dose multiagent chemotherapy without radiation therapy to his neck who, within 1 year of treatment, developed a low-grade but large and locally aggressive mucoepidermoid carcinoma of his parotid gland further characterized by a t(11;19)(q21;p13.1). Our patient extends the spectrum of secondary neoplasms after neuroblastoma.

Polymorphisms in NAT2 and GSTP1 are associated with survival in oral and oropharyngeal cancer

INTRODUCTION

Functional polymorphisms in drug metabolizing enzymes (DMEs) may be determinants of survival in oral and oropharyngeal squamous cell carcinoma (OOSCC).

METHODS

OOSCC cases (N=159) with a history of either tobacco or alcohol use were genotyped for polymorphisms in eight DMEs. Overall and disease-specific survival were analyzed using Kaplan-Meier plots and the log-rank test. Cox proportional hazards regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) in exploratory analyses of patient subgroups.

RESULTS

Kaplan-Meier analyses showed N-acteyltransferase-2 (NAT2) fast acetylators experienced a 19.7% higher 5-year survival rate than slow acetylators (P=0.03) and this association was similar in oropharyngeal and oral cancer. After multiple adjustment, including tumor site and stage, the NAT2 fast acetylator phenotype was associated with improved overall survival (vs. slow acetylators) provided chemotherapy or radiation were not used (HR, 0.26; 95% CI, 0.10-0.66). However, NAT2 phenotype was unrelated to survival in patients treated with chemoradiotherapy (HR, 1.21; 95% CI, 0.54-2.73) or radiotherapy (HR, 0.67; 95% CI, 0.31-1.59) (P-for-NAT2/treatment-interaction=0.04). Normal activity GSTP1 was associated with a 19.2% reduction in 5-year disease-specific survival relative to reduced activity GSTP1 (P=0.04) but this association was not modified by treatment.

CONCLUSIONS

Our results suggest that functional polymorphisms in NAT2 and GSTP1 are associated with OOSCC survival. Confirmation of these results in larger studies is required.

GSTM1 copy number and promoter haplotype as predictors for risk of recurrence and/or second primary tumor in patients with head and neck cancer

The objective of this study was to determine copy number variant (CNV) and promoter genetic variants in glutathione S-transferase Mu class 1 (GSTM1) and the risk of recurrence (REC)/second primary tumor (SPT) in patients with previously diagnosed early stage head and neck cancer. Among 441 subjects, 133 experienced REC and/or an SPT, while 308 had single primary disease. TaqMan real-time polymerase chain reaction was used to measure the exact copy number of GSTM1 and direct sequencing was used to determine genetic variants in the GSTM1 promoter region. Multivariate Cox regression analysis was performed to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) associated with copy number and genetic variants. REC/SPT-free survival times were compared by constructing Kaplan–Meier curves and differences between curves were tested by logrank test. Results showed a significantly decreased REC/SPT (HR = 0.57; 95% CI = 0.35–0.95) and longer REC/SPT-free survival in subjects with at least two copies of GSTM1 compared with the GSTM1 homozygous deletion, but not in those with one copy of GSTM1. The −498G, −426G, and −339T alleles were significantly associated with REC/SPT, with HRs of 0.11 (0.02–0.85), 0.28 (0.11–0.74) and 2.02 (1.07–3.82), respectively. Kaplan–Meier survival analysis showed that the −498G, −426G, and −339C alleles were also significantly associated with increased REC/SPT-free survival. Further haplotype analysis showed the haplotype P^{−498G-−426G-−339C} carriers had decreased REC/SPT with a HR of 0.09 (95% CI 0.01–0.71) and increased REC/SPT-free survival compared with those with haplotype P^{−498C-−426A-−339T}. The P^{−498C-−426A-−339T}-containing reporter construct had significantly increased luciferase expression. These results suggest that the GSTM1 CNV and promoter haplotype are better predictors of REC/SPTs of head and neck cancer than just measuring the presence/absence of GSTM1.

Genetic susceptibility to multiple primary neoplasms in the upper aero-digestive tract: genotype score and phenotype correlation

Early detection and treatment of head and neck cancer has led to increased patient survival. However such patients are at a high risk for multiple primary neoplasm(s) (MPN). In order to study the genetic susceptibility to MPN, 22 candidate SNPs were genotyped based on which a distinctive Genotype Score was created using Additive, Dominant and Recessive models. Using lymphoblastoid cell lines (LCLs) generated from these individuals, the Genotype Score was correlated with carcinogen sensitivity in vitro. LCLs from MPN patients exhibited significantly higher Genotype Score and showed resistance to genotoxic agents compared to matched controls. This report demonstrates quantitative assessment of cumulative effect of gene polymorphisms and its correlation with carcinogen sensitivity for predicting susceptibility to MPN.

Genetic variants of p27 and p21 as predictors for risk of second primary malignancy in patients with index squamous cell carcinoma of head and neck

Background

Cell cycle deregulation is common in human cancer, and alterations of p27 and p21, two critical cell cycle regulators, have been implicated in the development of many human malignancies. Therefore, we hypothesize that p27 T109G polymorphism individually or in combination with p21 (C98A and C70T) polymorphisms modifies risk of second primary malignancy (SPM) in patients with index squamous cell carcinoma of head and neck (SCCHN).

Methods

A cohort of 1,292 patients with index SCCHN was recruited between May 1995 and January 2007 at the M.D. Anderson Cancer Center and followed for SPM occurrence. Patients were genotyped for the three polymorphisms. A log-rank test and Cox proportional hazards models were used to compare SPM-free survival and SPM risk.

Results

We found that patients with p27 109 TG/GG, p21 98 CA/AA and p21 70 CT/TT variant genotypes had a worse SPM-free survival and an increased SPM risk than those with the corresponding p27109 TT, p21 98 CC, and p21 70 CC common genotypes, respectively. After combining the three polymorphisms, there was a trend for significantly increased SPM risk with increasing number of the variant genotypes (P_trend = 0.0002). Moreover, patients with the variant genotypes had an approximately 2.4-fold significantly increased risk for SPM compared with those with no variant genotypes (HR, 2.4, 95% CI, 1.6-3.6).

Conclusions

These results suggest that p27 T109G polymorphism individually or in combination with p21 (C98A and C70T) polymorphisms increases risk of SPM in patients with index SCCHN.

Genetic sequence variants and the development of secondary primary cancers in patients with head and neck cancers

BACKGROUND

Secondary primary cancers (SPCs), a major cause of morbidity and mortality in head and neck cancers (HNCs), are commonly associated with field cancerization. We comprehensively evaluated 23 germline sequence variants (from published literature) in 17 genes from 7 biological pathways associated with the HNC survival. Because cancer prognosis correlates with disease aggressiveness, the factors that determine aggressive disease may influence field cancerization process to favor SPC development. We thus hypothesized that the same sequence variants associated with HNC survival can also be associated with SPC.

METHODS

Germline DNA from 531 stage I-II radiation-treated HNC patients (originally recruited for an alpha-tocopherol/beta-carotene placebo-controlled secondary prevention clinical trial) were genotyped, and analyzed using Cox proportional hazards models, stratified by treatment arm, adjusting for clinical prognostic factors.

RESULTS

The majority of SPCs were of lung and HNCs. Median follow-up time was 5 years. SPCs were diagnosed in 21% of patients. The 5-year SPC-free survival was 79%. All but 1 evaluated sequence variant were not associated with SPC. There was a strong association of the DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) sequence variant, DNMT3B:C149T (rs2424913) with SPC: the adjusted hazard ratio (aHR) for TT versus CC was 2.23 (1.32-3.78; P = .003), whereas each variant T allele was associated with an aHR of 1.49 (1.15-1.95; P = .003).

CONCLUSIONS

A functional sequence variant in DNMT3B is associated with the development of SPCs in HNC early stage patients treated with radiation. Aberrant DNA methylation may be an important modulator of SPC development in at-risk individuals with HNCs.

Polymorphisms in GSTM1 and XPD genes predict clinical outcome in advanced oral cancer patients treated with postoperative radiotherapy

Polymorphisms in metabolic and DNA repair genes may alter protein function, consequently affecting patients' response to chemo/radiotherapy. We retrospectively assessed whether polymorphisms of glutathione-S-transferase genes GSTM1 (deletion), GSTT1 (deletion), GSTP1 (Ile105Val, rs1695), and DNA repair genes hOGG1 (Ser326Cys, rs1052133), XRCC1 (Arg194Trp, rs1799782, and Arg399Gln, rs25487), XPD (Asp312Asn, rs1799793, and Lys751Gln, rs13181) can predict clinical outcome in 187 oral squamous cell carcinoma patients treated with postoperative radiotherapy. The Cox proportional hazards model was used to evaluate the role of polymorphic genotypes on relapse-free (RFS) and disease-specific (DSS) survival. Deletion polymorphism of GSTM1 gene was significantly associated with DSS. The rs1799793 variant allele showed significant protection in both DSS and RFS. Significant increase in RFS but not in DSS was observed with polymorphic rs13181. The combined analysis of GSTM1 and XPD polymorphisms revealed favorable effect on survival. GSTM1 and XPD variant alleles, independently as well as in combination may serve as important predictors of clinical outcome in radiotherapy-treated OSCC patients.

A strong case for personalized, targeted cancer prevention

The study reported by Lee and colleagues in this issue of the journal (beginning on page 185) incorporated global genetic variation within a new assessment of the outcome of a previously reported phase-III trial of low-dose 13-cis-retinoic acid (13-cRA) for preventing second primary tumors (SPT) or the recurrence of head-and-neck cancer. This analysis identified genotypes of common single-nucleotide polymorphisms (SNP) and cumulative effect and potential gene-gene interactions that were highly associated with increased placebo-arm risk (prognostic) and/or with reduced treatment-arm risk and longer event-free survival (predictive). For example, the wild-type rs3118570 SNP of the retinoid X receptor alpha gene (carried by 71% of the 13-cRA trial population) marked a 3.33-fold increased SPT/recurrence risk in the placebo arm and a 38% reduced risk in the treatment arm. Adding two other informative genotypes strengthened the treatment-arm risk reduction to 76%, although the genotype trio reflected only 13% of the trial population. This report extends the concept of personalized therapy to cancer prevention.

p14ARF genetic polymorphisms and susceptibility to second primary malignancy in patients with index squamous cell carcinoma of the head and neck

BACKGROUND

p14(ARF) , an alternate reading frame (ARF) product of the cyclin-dependent kinase inhibitor 2A locus, plays a critical role in crosstalk between the tumor protein 53 (p53) and retinoblastoma (Rb) pathways and in cellular anticancer mechanisms. Therefore, the authors of this report investigated the association between single nucleotide polymorphisms (SNPs) of the p14(ARF) gene and the risk of developing a second primary malignancy (SPM) after an index squamous cell carcinoma of the head and neck (SCCHN).

METHODS

The log-rank test and Cox proportional hazards models were used to assess the association of 2 p14(ARF) SNPs (reference SNP [rs]3731217 and rs3088440) with SPM-free survival and with the risk of developing an SPM among 1287 patients who had SCCHN.

RESULTS

Patients with either p14(ARF) variant genotypes of the 2 polymorphisms had a significantly reduced SPM-free survival compared with patients with no variant genotypes (log-rank test; P = .006). Compared with the p14(ARF) thymine-thymine (TT) and guanine-guanine (GG) genotypes, the variant genotypes of p14(ARF) TG/GG and guanine-adenine (GA)/AA were associated with a significantly moderately increased risk of developing an SPM (p14(ARF) rs3731217: adjusted hazard ratio [aHR], 1.48; 95% confidence interval [CI], 1.00-2.19; p14(ARF) rs3088440: aHR, 1.61; 95% CI, 1.07-2.43). Moreover, after combining the variant genotypes of the 2 SNPs, patients who had variant genotypes were at significantly greater risk of developing an SPM compared with patients who had no variant genotypes (aHR, 3.07; 95% CI, 1.54-6.12), and the risk was particularly pronounced in several subgroups.

CONCLUSIONS

The current results suggested that there is a modestly increased risk of developing an SPM after an index SCCHN with each p14(ARF) polymorphism, and there is an even greater risk of developing an SPM for patients with combined variant genotypes of the 2 SNPs. Therefore, p14(ARF) polymorphisms may be susceptible markers of the risk of developing an SPM in patients with SCCHN.

Association of p53 codon 72 polymorphism with risk of second primary malignancy in patients with squamous cell carcinoma of the head and neck

BACKGROUND

p53 plays a critical role in cellular anticancer mechanisms, and has been correlated with second primary malignancy (SPM) development. A common polymorphism in codon 72 of p53 results in an amino acid substitution and could influence p53 function. The authors hypothesized that p53 codon 72 polymorphism may be associated with risk of SPMs and SPM-free survival among patients with squamous cell carcinoma of the head and neck (SCCHN).

METHODS

A total of 1271 patients, who were diagnosed with incident SCCHN between May 1995 and January 2007, were genotyped and observed for SPM development. Log-rank test and Cox proportional hazard models were used to compare SPM-free survival and SPM risk between the different genotype groups.

RESULTS

The authors found significantly reduced SPM-free survival for patients with variant proline (Pro) 72 allele compared with patients with arginine (Arg) 72 homozygous genotype (log-rank test, P = .005). Compared with SCCHN patients with the p53 72Arg/Arg genotype, there was a significantly greater risk of SPM associated with the p53 72Arg/Pro genotype (hazard ratio [HR], 1.75; 95% confidence interval [CI], 1.17-2.61) and combined p53 72Arg/Pro + Pro/Pro (HR, 1.58; 95% CI, 1.07-2.34). Furthermore, stratification analyses showed that the risk of SPM associated with p53 variant genotypes (Arg/Pro + Pro/Pro) was more pronounced in several subgroups.

CONCLUSIONS

p53 codon 72 polymorphism could be a risk marker for genetic susceptibility to SPM in patients with primary SCCHN.

FAS and FASLG genetic variants and risk for second primary malignancy in patients with squamous cell carcinoma of the head and neck

BACKGROUND

Single-nucleotide polymorphisms in the promoter region of the FAS and FASLG may alter the transcriptional activity of these genes. We therefore investigated the association between the FAS and FASLG polymorphisms and risk for second primary malignancy (SPM) after index squamous cell carcinoma of the head and neck (SCCHN).

METHODS

We used log-rank test and Cox proportional hazard models to assess the association of the four single-nucleotide polymorphisms (FAS -1377 G > A, FAS -670 A > G, FASLG -844 C > T, and FASLG -124 A > G) with the SPM-free survival and SPM risk among 1,286 incident SCCHN patients.

RESULTS

Compared with patients having the FAS -670 AA or the FASLG -844 CC genotypes, the patients having variant genotypes of FAS -670 AG/GG or FASLG -844 CT/TT genotypes had significantly increased risk for SPM, respectively. A trend for significantly increased SPM risk with increasing number of risk genotypes of the four polymorphisms was observed in a dose-response manner. Moreover, the patients with three or four combined risk genotypes had an approximately 1.8- or 2.5-fold increased risk for developing SPM compared with patients with zero or one risk genotypes, respectively.

CONCLUSIONS

Our results suggest a modestly increased risk for SPM after index SCCHN with FAS -670 A > G and FASLG -844 C > T polymorphisms and an even greater risk for SPM with multiple combined FAS and FASLG risk genotypes.

IMPACT

The FAS and FASLG polymorphisms may serve as a susceptible marker for SCCHN patients at high SPM risk.

Glutathione S-transferases: an overview in cancer research

IMPORTANCE OF THE FIELD

The Glutathione S-transferases (GSTs) have advanced beyond the classic view of their role in metabolism and are encouraging scientists to assess new approaches to cancer risk characterization and chemotherapy resistance and are opening up exciting possibilities in drug discovery.

AREAS COVERED IN THIS REVIEW

In this review, the most recent knowledge about the impact of GST genetic polymorphisms in human's cancer susceptibility, ethnic differences in the effects of risk factors and the rise of the GSTs as important targets for drug development are presented. In this context, the ethnic distribution of GST alleles in different populations, which is an important concept that is being incorporated in epidemiologic studies of cancer risk and environmental exposure, was also evaluated. We present up-to-date information about the new generation of GST-activated cytotoxic prodrugs based on GST overexpression in tumor-acquired drug resistance and the newest results of clinical trials.

WHAT THE READER WILL GAIN

A critical approach of the major advances in research of GST, underlining the new advances of GST genes polymorphisms in cancer susceptibility and target for therapeutic intervention.

TAKE HOME MESSAGE

Although polygenic factors are involved in increased risk of cancer, the interindividual GST variability plays a central role in reduce cells exposure to carcinogens.

Genetic polymorphisms of p21 and risk of second primary malignancy in patients with index squamous cell carcinoma of the head and neck

p21 plays an important role in modulating cell cycle control, inducing apoptosis, and inhibiting cell growth, subsequently affecting cancer risk. We investigated the association between two putatively functional single-nucleotide polymorphisms (SNPs) of p21 (p21 C98A and p21 C70T) among 1282 patients diagnosed with incident squamous cell carcinoma of the head and neck (SCCHN) and risk of second primary malignancy (SPM) in an ongoing molecular epidemiology study. We used Log-rank test and Cox proportional hazard models to assess the association of these two SNPs with SPM-free survival and SPM risk. We found that patients with either p21 variant genotypes of the two polymorphisms had a significantly reduced SPM-free survival compared with patients with either p21 wild-type homozygous genotypes (Log-rank test, P = 0.0016). Compared with patients having the p21 98 CC and p21 70 CC genotypes, the patients having p21 98 CA/AA and p21 70 CT/TT variant genotypes had a significantly greater risk of developing SPM, respectively, [hazard ratio (HR) = 1.80, 95% CI = 1.14-2.82 for p21 C98A and HR = 1.82, 95% confidence interval (CI) = 1.16-2.85 for p21 C70T]. Moreover, after combining the variant genotypes of two SNPs, patients with variant genotypes had a significantly moderately increased risk for SPM compared with patients with no variant genotypes (HR = 2.00, 95% CI = 1.26-3.00), and the risk was particularly pronounced in several subgroups. Our results support an increased risk of SPM after index SCCHN with both p21 polymorphisms individually and in combination.

Glutathione S-transferase polymorphisms and risk of second primary malignancy after index squamous cell carcinoma of the head and neck

Glutathione S-transferases (GST) detoxify carcinogens in tobacco smoke, which plays a major role in development of not only squamous cell carcinoma of the head and neck (SCCHN) but also second primary malignancy (SPM) after index SCCHN. We hypothesized that GSTM1 null, GSTT1 null, GSTP1 Ile(105)Val, and GSTP1 Ala(114)Val polymorphisms would individually and, more likely, collectively show an association with risk of SPM after index SCCHN. One thousand three hundred seventy-six incident SCCHN patients were prospectively recruited between May 1996 and December 2006, genotyped, and followed for SPM development. One hundred ten patients (8%) developed SPM: 43 (39%) second SCCHN, 38 (35%) other tobacco-associated sites, and 29 (26%) other non-tobacco-associated sites. Patients with GSTP1 Ile(105)Val polymorphism had a statistically significant association with risk of SPM development (adjusted hazard ratio, 1.7; 95% confidence interval, 1.1-2.5). However, no statistically significant associations were observed with GSTM1, GSTT1, or GSTP1 Ala(114)Val polymorphisms. After combining risk genotypes for all four polymorphisms, rates of SPM development with 0 to 1, 2, 3, and 4 risk genotypes were 6.4%, 8.4%, 10.9%, and 15.1%, respectively, and a stepwise increase in SPM risk was observed with increasing number of risk genotypes (P = 0.004 for trend). Patients with 3 to 4 risk genotypes had a 1.7-fold increased risk for SPM compared with patients with 0 to 2 risk genotypes (hazard ratio, 1.70; 95% confidence interval, 1.2-2.5). This large prospective cohort study supports a modestly increased risk of SPM after index SCCHN with GSTP1 Ile(105)Val polymorphism and an even greater risk of SPM with multiple combined GST risk genotypes.

Genetic polymorphisms and head and neck cancer outcomes: a review

Head and neck cancer (HNC) patients have variable prognoses even within the same clinical stage and while receiving similar treatments. The number of studies of genetic polymorphisms as prognostic factors of HNC outcomes is growing. Candidate polymorphisms have been evaluated in DNA repair, cell cycle, xenobiotic metabolism, and growth factor pathways. Polymorphisms of XRCC1, FGFR, and CCND1 have been consistently associated with HNC survival in at least two studies, whereas most of the other polymorphisms have either conflicting data or were from single studies. Heterogeneity and lack of description of patient populations and lack of accounting for multiple comparisons were common problems in a significant proportion of studies. Despite a large number of exploratory studies, large replication studies in well-characterized HNC populations are warranted.

Inherited susceptibility to bleomycin-induced micronuclei: correlating polymorphisms in GSTT1, GSTM1 and DNA repair genes with mutagen sensitivity

Susceptibility to DNA damage varies among individuals and sensitivity to bleomycin (BLM) may reflect the inter-individual differences. BLM sensitivity in part may be explained by inherited differences in DNA repair genes. We investigated the association between genetic polymorphisms in the GSTT1, GSTM1, XPD, XRCC1 and XRCC3 genes and the levels of spontaneous and BLM-induced DNA damage in peripheral blood lymphocytes from 200 healthy, unexposed individuals. The investigation of BLM sensitivity on cancer- or disease-free subjects and not occupationally exposed to known mutagen represents the strengths of the present study, as the detection of genetic damage is not biased by any disease- and occupational-related factor. The micronucleus (MN) assay was used to detect the spontaneous and BLM-induced genetic damage whereas, genotype analysis was carried out using methods based on polymerase chain reaction. Poisson regression analysis showed that subject's age, gender and smoking status had no effect on the spontaneous and BLM-induced MN frequencies. Genotype analysis revealed a clear association between GSTT1-null and XPD polymorphisms and both spontaneous and BLM-induced MN frequencies, whereas the effect of the XRCC1 polymorphism was marginally significant only with regard to spontaneous MN frequency. Genotype analysis did not reveal a clear association between the other studied SNPs (GSTM1 and XRCC3) and MN frequencies. Poisson regression analysis revealed no association between the score of protective alleles and the frequency of spontaneous MN. However, an increased number of protective alleles was significantly associated with a lower frequency of BLM-induced MN (P=0.0003). This finding highlights the genetic basis for BLM sensitivity, which could be a valid and useful surrogate for identifying genotypes that might increase susceptibility in population exposed to carcinogens. Further investigations in a large sample size and including more SNPs, reflecting the complexity of DNA repair machinery, might lead to the identification of a genetic profile responsible for the susceptibility to genotoxicants, with a far-reaching long-term impact on primary prevention and early detection of disease associated genes.

GSTT1 and GSTM1 polymorphism in cigarette smokers with head and neck squamous cell carcinoma

Gene variability related to carcinogen activation and detoxification may interfere with susceptibility to head and neck cancer.

Aim

To investigate the relation between GSTT1 and GSTM1 null polymorphisms and the risk of head and neck squamous cell carcinoma in cigarette smokers.

Material and Method

A case-control study conducted at the Sao Jose do Rio Preto Medical School, Brazil. GSTM1 and GSTT1 null genotype frequencies were evaluated by multiplex PCR in ⁴⁵ cigarette smokers with head and neck squamous cell carcinomas and ⁴⁵ cigarette smokers without this disease.

Results

The oral cavity was the most prevalent tumor site for squamous cell carcinoma. The GSTT1 null genotype was found in 33.3% of the Experimental Group and 23.3% of the Control Group (p= 0.311). Experimental and Control Groups had GSTM1 null genotype frequencies of 35% and 48.3% (p=0.582). No association between alcohol consumption and GSTT1 and GSTMI null genotypes was found in these groups (p-values>0.05). There were more men, and alcohol consumption was prevalent in both groups.

Conclusion

In this study we were unable to show a correlation between GSTM1 and GSTT1 genotypes and the development of head and neck squamous cell carcinomas in cigarette smokers.

Chemoprevention of squamous cell carcinoma of the head and neck

PURPOSE OF REVIEW

The aim of this article is to summarize progress in understanding of the biology of squamous cell carcinoma of the head and neck and of trials to prevent malignant conversion of oral premalignant lesions and the development of second primary tumors in those already treated for squamous cell carcinoma of the head and neck.

RECENT FINDINGS

The understanding of squamous cell carcinoma of the head and neck biology is rapidly evolving. Clinical trials for chemoprevention are involving more diverse regimens, following disappointing results of retinoid monotherapy. In-vitro and animal studies form the rationale for the next generation of studies, employing combination, synergistic treatments.

SUMMARY

Based on trial data to date, no recommendation for intervention with a chemopreventive agent can be made. It is clear, however, that smoking cessation is an effective intervention for preventing oral premalignant lesions and second primary tumors. Promising trials are being conducted and designed currently. The future of this area of study will involve rational choice of multidrug regimens based on current understanding of the biology of squamous cell carcinoma of the head and neck.