XPD c.934G>A polymorphism of nucleotide excision repair pathway in outcome of head and neck squamous cell carcinoma patients treated with cisplatin chemoradiation

Genetic Polymorphisms of XPC, XPD, XPG Genes and their Association with Radiotherapy Induced Toxicity among Head and Neck Cancer Patients: A Hospital Based Study from Maharashtra

BACKGROUND

The present study was planned to investigate possible association of single nucleotide polymorphisms (SNPs) of nucleotide excision repair (NER) genes such as XPC, XPD, XPG with acute radiation induced toxicities such as skin reactions and oral mucositis in normal tissue from head and neck cancer (HNC) patients receiving radiotherapy.  Methods: Two hundred and fifty HNC patients receiving radiotherapy were enrolled in this study and the acute toxicity reactions and radiation response were recorded. Association of SNPs rs2228001 of XPC, rs238406, rs13181 of XPD and rs17655 of XPG gene with normal tissue reactions in the form of dermatitis and mucositis were studied by PCR-RFLP and direct DNA sequencing.

RESULTS

The results of univariate analysis of SNPs of XPC, XPD and XPG showed that XPC polymorphism at codon 939 of exon 15 (A>C) was not associated with dermatitis (OR=0.30, 95% CI: 0.06-1.39; p=0.125), or oral mucositis (OR=1.14, 95% CI: 0.41-3.20; p=0.793). The XPD codon 156 of exon 6 (C>A) and codon 751 of exon-23 A>C) polymorphism showed no association with radiosensitivity in HNC patients (OR=1.50, 95% CI: 0.60-3.71; p=0.080) for dermatitis, (OR=1.54, 95% CI: 0.66-3.61; p=0.312) for oral mucositis. The 1104 Asp variant genotype or allele of XPG (OR=1.35 95% CI: 0.50-3.64; p=0.541) showed no association with degree of radiotherapy associated dermatitis or mucositis (OR=0.80, 95% CI: 0.32-2.03; p=0.648) in HNC patients. The variant C allele of 2920 A/C genotype of XPC gene at codon 939 of exon 15, found protective with developing skin reactions with grade >1 (OR=0.60, 95% CI: 0.36-0.97; p=0.039) in HNC patients treated with radiotherapy.

CONCLUSION

The results obtained in this study concluded that the SNPs rs2228001of XPC, rs238406, rs13181 SNPs of XPD and rs17655 SNP of XPG are not associated with normal tissue toxicity in HNC patients treated with radiotherapy. Radiotherapy with high radiation dose was significantly associated with oral mucositis in response to radiotherapy.

Systematic Critical Review of Genetic Factors Associated with Cisplatin-induced Ototoxicity: Canadian Pharmacogenomics Network for Drug Safety 2022 Update

BACKGROUND

Cisplatin is commonly used to treat solid tumors; however, its use can be complicated by drug-induced hearing loss (ie, ototoxicity). The presence of certain genetic variants has been associated with the development/occurrence of cisplatin-induced ototoxicity, suggesting that genetic factors may be able to predict patients who are more likely to develop ototoxicity. The authors aimed to review genetic associations with cisplatin-induced ototoxicity and discuss their clinical relevance.

METHODS

An updated systematic review was conducted on behalf of the Canadian Pharmacogenomics Network for Drug Safety, based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 statement. Pharmacogenomic studies that reported associations between genetic variation and cisplatin-induced ototoxicity were included. The evidence on genetic associations was summarized and evaluated, and knowledge gaps that can be used to inform future pharmacogenomic studies identified.

RESULTS

Overall, 40 evaluated reports, considering 47 independent patient populations, captured associations involving 24 genes. Considering GRADE criteria, genetic variants in 2 genes were strongly (ie, odds ratios ≥3) and consistently (ie, replication in ≥3 independent populations) predictive of cisplatin-induced ototoxicity. Specifically, an ACYP2 variant has been associated with ototoxicity in both children and adults, whereas TPMT variants are relevant in children. Encouraging evidence for associations involving several other genes also exists; however, further research is necessary to determine potential clinical relevance.

CONCLUSIONS

Genetic variation in ACYP2 and TPMT may be helpful in predicting patients at the highest risk of developing cisplatin-induced ototoxicity. Further research (including replication studies considering diverse pediatric and adult patient populations) is required to determine whether genetic variation in additional genes may help further identify patients most at risk.

Genetic variability in cisplatin metabolic pathways and outcome of locally advanced head and neck squamous cell carcinoma patients

Advanced head and neck squamous cell carcinoma (HNSCC) patients have been treated with cisplatin (CDDP) chemoradiation, and the variability of treatment effects has been attributed to single nucleotide variants (SNVs) in genes of metabolic pathways. This study investigated the roles of GSTM1, GSTT1, GSTP1 c.313A>G, XPC c.2815A>C, XPD c.934G>A and c.2251A>C, XPF c.2505T>C, ERCC1 c.354C>T, MLH1 c.93G>A, MSH2 c.211+9C>G, MSH3 c.3133G>A, EXO1 c.1765G>A, TP53 c.215G>C, CASP3 c.-1191A>G and c.-182-247G>T, FAS c.-1378G>A and c.-671A>G and FASL c.-844C>T SNVs in outcome of 109 patients treated with CDDP chemoradiation. Genotypes were identified in genomic DNA by PCR-based methods. Conventional criteria and tests analyzed response and survival. Patients with XPC c.2815AC or CC had 3.43 times more chances of presenting partial response or stable disease. Patients with FAS c.-671GG, GSTM1 present plus XPC c.2815AA, or plus XPD c.934GG, or plus XPD c.2251AA, or plus TP53 c.215GC or CC, and XPD c.2251AA plus XPF c.2505TT had up to 2.70 and 2.37 times more chances of presenting tumor progression and evolving to death, respectively. Our data indicate, for the first time, preliminary evidence that combined SNVs of CDDP metabolism act as independent prognostic factors and can be used to select patients for distinct treatments.

Association of Clinical Aspects and Genetic Variants with the Severity of Cisplatin-Induced Ototoxicity in Head and Neck Squamous Cell Carcinoma: A Prospective Cohort Study

Background: Cisplatin (CDDP) is a major ototoxic chemotherapy agent for head and neck squamous cell carcinoma (HNSCC) treatment. Clinicopathological features and genotypes encode different stages of CDDP metabolism, as their coexistence may influence the prevalence and severity of hearing loss. Methods: HNSCC patients under CDDP chemoradiation were prospectively provided with baseline and post-treatment audiometry. Clinicopathological features and genetic variants encoding glutathione S-transferases (GSTT1, GSTM1, GSTP1), nucleotide excision repair (XPC, XPD, XPF, ERCC1), mismatch repair (MLH1, MSH2, MSH3, EXO1), and apoptosis (P53, CASP8, CASP9, CASP3, FAS, FASL)-related proteins were analyzed regarding ototoxicity. Results: Eighty-nine patients were included, with a cumulative CDDP dose of 260 mg/m2. Moderate/severe ototoxicity occurred in 26 (29%) patients, particularly related to hearing loss at frequencies over 3000 Hertz. Race, body-mass index, and cumulative CDDP were independent risk factors. Patients with specific isolated and combined genotypes of GSTM1, GSTP1 c.313A>G, XPC c.2815A>C, XPD c.934G>A, EXO1 c.1762G>A, MSH3 c.3133A>G, FASL c.-844A>T, and P53 c.215G>C SNVs had up to 32.22 higher odds of presenting moderate/severe ototoxicity. Conclusions: Our data present, for the first time, the association of combined inherited nucleotide variants involved in CDDP efflux, DNA repair, and apoptosis with ototoxicity, which could be potential predictors in future clinical and genomic models.

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

Background

Head and neck squamous cell carcinomas (HNSCCs) are associated with variable prognosis even with similar clinical characteristics and treatments. Gene polymorphisms have been suggested as prognostic factors for HNSCC which can justified this variable prognosis. So, the aim was to review literatures on gene polymorphisms and prognosis of HNSCCs.

Materials and methods

A systematic search was conducted using PubMed, Web of science, SCOPUS, Google Scholar and Cochrane library databases to find all related articles published up to December 2021 in the field of gene polymorphisms and HNSCC prognosis.

Results

Of 1029 initial searched articles, 71 articles were selected for inclusion in this systematic review. About 93 genes and 204 polymorphisms have been discussed in these articles. Among the most studied polymorphisms, the XRCC1 Arg399Gln and Arg194Trp polymorphisms were not associated with survival in most studies; the ERCC1 C19007T polymorphism had no significant association in any of the studies. Different gene polymorphisms of glutathione s-transferase family, including GSTM1 deletion, GSTT1 deletion and GSTP1 A313G, were not associated with survival in included studies. There are conflicting results regarding the association between polymorphisms such as ERCC2 A35931C, Asp312Asn, ERCC5 rs1047768 and rs17655 with HNSCC prognosis. Less studied polymorphisms, such as hOGG1 rs1052133 or the VEGF rs699947, were generally not associated with HNSCC prognosis.

Conclusion

Reviewed articles reported varied and contradictory results regarding the association of gene polymorphisms and HNSCC prognosis, which necessitates further studies along with meta-analysis on the results of such studies.

Pharmacogenetics of chemotherapy treatment response and -toxicities in patients with osteosarcoma: a systematic review

BACKGROUND

Osteosarcoma is the most common bone tumor in children and adolescents. Despite multiagent chemotherapy, only 71% of patients survives and these survivors often experience long-term toxicities. The main objective of this systematic review is to provide an overview of the discovery of novel associations of germline polymorphisms with treatment response and/or chemotherapy-induced toxicities in osteosarcoma.  METHODS: MEDLINE and Embase were systematically searched (2010-July 2022). Genetic association studies were included if they assessed > 10 germline genetic variants in > 5 genes in relevant drug pathways or if they used a genotyping array or other large-scale genetic analysis. Quality was assessed using adjusted STrengthening the REporting of Genetic Association studies (STREGA)-guidelines. To find additional evidence for the identified associations, literature was searched to identify replication studies.

RESULTS

After screening 1999 articles, twenty articles met our inclusion criteria. These range from studies focusing on genes in relevant pharmacokinetic pathways to whole genome sequencing. Eleven articles reported on doxorubicin-induced cardiomyopathy. For seven genetic variants in CELF4, GPR35, HAS3, RARG, SLC22A17, SLC22A7 and SLC28A3, replication studies were performed, however without consistent results. Ototoxicity was investigated in one study. Five small studies reported on mucosistis or bone marrow, nephro- and/or hepatotoxicity. Six studies included analysis for treatment efficacy. Genetic variants in ABCC3, ABCC5, FasL, GLDC, GSTP1 were replicated in studies using heterogeneous efficacy outcomes.

CONCLUSIONS

Despite that results are promising, the majority of associations were poorly reproducible due to small patient cohorts. For the future, hypothesis-generating studies in large patient cohorts will be necessary, especially for cisplatin-induced ototoxicity as these are largely lacking. In order to form large patient cohorts, national and international collaboration will be essential.

GSTP1 and ABCB1 Polymorphisms Predicting Toxicities and Clinical Management on Carboplatin and Paclitaxel-Based Chemotherapy in Ovarian Cancer

Variation in drug disposition genes might contribute to susceptibility to toxicities and interindividual differences in clinical management on chemotherapy for epithelial ovarian cancer (EOC). This study was designed to explore the association of GST and ABCB1 genetic variation with hematologic and neurologic toxicity, changes in chemotherapy, and disease prognosis in Brazilian women with EOC. A total of 112 women with a confirmed histological diagnosis of EOC treated with carboplatin/paclitaxel were enrolled (2014–2019). The samples were analyzed by multiplex polymerase chain reaction (PCR) for the deletion of GSTM1 and GSTT1 genes. GSTP1 (c.313A>G/rs1695) and ABCB1 (c.1236C>T/rs1128503; c.3435C>T/rs1045642; c.2677G>T>A/rs2032582) single nucleotide polymorphisms (SNPs) were detected by real‐time PCR. Subjects with the GSTP1 c.313A>G had reduced risk of anemia (odds ratio (OR): 0.17, 95% confidence interval (CI): 0.04–0.69, P = 0.01, dominant model) and for thrombocytopenia (OR: 0.27, 95% CI: 0.12–0.64, P < 0.01; OR 0.18, 95% CI 0.03–0.85, P = 0.03, either dominant or recessive model), respectively. The GSTP1 c.313A>G AG genotype was associated with a lower risk of dose delay (OR: 0.35, 95% CI: 0.13–0.90, P = 0.03). The ABCB1 c.1236C>T was associated with increased risk of thrombocytopenia (OR: 0.15, 95% CI: 0.03–0.82, P = 0.03), whereas ABCB1 c.3435C>T had increased risk of grade 2 and 3 neurotoxicity (OR: 3.61, 95% CI: 1.08–121.01, P = 0.03) in recessive model (CC + CT vs. TT). This study suggests that GSTP1 c.313A>G, ABCB1 c.1236C>T, and c.3435C>T SNP detection is a potential predictor of hematological toxicity and neurotoxicity and could help predict the clinical management of women with EOC.

FAS and FASL variations in outcomes of tobacco- and alcohol-related head and neck squamous cell carcinoma patients

Radiotherapy and cisplatin lead to cell killing in head and neck squamous cell carcinoma patients, but adverse events and response to treatment are not the same in patients with similar clinicopathological aspects. The aim of this prospective study was to evaluate the roles of TP53 c.215G > C, FAS c.-671A > G, FAS c.-1378G > A, FASL c.-844 C > T, CASP3 c.-1191A > G, and CASP3 c.-182-247G > T single nucleotide variants in toxicity, response rate, and survival of cisplatin chemoradiation-treated head and neck squamous cell carcinoma patients. Genomic DNA was analyzed by polymerase chain reaction for genotyping. Differences between groups of patients were analyzed by chi-square test or Fisher's exact test, multiple logistic regression analysis, and Cox hazards model. One hundred nine patients with head and neck squamous cell carcinoma were enrolled in study. All patients were smokers and/or alcoholics. Patients with FAS c.-671GG genotype, FAS c.-671AG or GG genotype, and FASL c.-844CC genotype had 5.52 (95% confidence interval (CI): 1.42-21.43), 4.03 (95% CI: 1.51-10.79), and 5.77 (95% CI: 1.23-27.04) more chances of presenting chemoradiation-related anemia of grades 2-4, lymphopenia of grade 3 or 4, and ototoxicity of all grades, respectively, than those with the remaining genotypes. FAS c.-671GG genotype was also seen as an independent predictor of shorter event-free survival (hazard ratio (HR): 2.05; P = 0.007) and overall survival (HR: 1.83; P = 0.02) in our head and neck squamous cell carcinoma patients. These findings present, for the first time, preliminary evidence that inherited abnormalities in apoptosis pathway, related to FAS c.-671A > G and FASL c.-844 C > T single nucleotide variants, can alter toxicity and survival of tobacco- and alcohol-related head and neck squamous cell carcinoma patients homogeneously treated with cisplatin chemoradiation.

ERCC2 gene single-nucleotide polymorphism as a prognostic factor for locally advanced head and neck carcinomas after definitive cisplatin-based radiochemotherapy

Identifying patients with locally advanced head and neck carcinoma on high risk of recurrence after definitive concurrent radiochemotherapy is of key importance for the selection for consolidation therapy and for individualized treatment intensification. In this multicenter study we analyzed recurrence-associated single-nucleotide polymorphisms (SNPs) in DNA repair genes in tumor DNA from 132 patients with locally advanced head and neck carcinoma (LadHnSCC). Patients were treated with definitive radiotherapy and simultaneous cisplatin-based chemotherapy at six partner sites of the German Cancer Consortium (DKTK) Radiation Oncology Group from 2005 to 2011. For validation, a group of 20 patients was available. Score selection method using proportional hazard analysis and leave-one-out cross-validation were performed to identify markers associated with outcome. The SNPs rs1799793 and rs13181 were associated with survival and the same SNPs and in addition rs17655 with freedom from loco-regional relapse (ffLRR) in the trainings datasets from all patients. The homozygote major rs1799793 genotype at the ERCC2 gene was associated with better (Hazard ratio (HR): 0.418 (0.234-0.744), p = 0.003) and the homozygote minor rs13181 genotype at ERCC2 with worse survival (HR: 2.074, 95% CI (1.177-3.658), p = 0.017) in comparison to the other genotypes. At the ffLRR endpoint, rs1799793 and rs13181 had comparable prognostic value. The rs1799793 and rs13181 genotypes passed the leave-one-out cross-validation procedure and associated with survival and ffLRR in patients with LadHnSCC treated with definitive radiochemotherapy. While findings were confirmed in a small validation dataset, further validation is underway within a prospective biomarker study of the DKTK.

Gene-environment and gene-gene interactions between CHRNA3 rs1051730, XRCC1 rs25487, and ERCC1 rs735482 variants highly elevate the risk of lung cancer

Background

Gene-gene and gene-environment interactions play an important role in cancer susceptibility. In this work, we studied the association of XRCC1 rs25487, ERCC1 rs735482, and CHRNA3 rs1051730 variants with lung cancer and assessed the modulatory effect of potential interaction between these variants on disease risk.

Results

In this study, 86 primary lung cancer patients and 64 control subjects were genotyped for CHRNA3 rs1051730, XRCC1 rs25487, and ERCC1 rs735482 by real-time PCR. The frequency of the three studied variants was higher among lung cancer patients than in control subjects, but with no statistical significance. ERCC1 rs735482 variant was associated with 6.9-fold increased risk to develop lung cancer among smokers (p = 0.03). Concomitant presence of CHRNA3 and ERCC1 wild alleles was associated with 2.7-fold elevated risk of lung cancer (p < 0.0001), while concomitant presence of CHRNA3 rs1051730 variant allele with ERCC1 wild allele was associated with 20-fold elevated risk (p < 0.000). Concomitant presence of both variants, ERCC1 rs735482 and CHRNA3 rs1051730, was associated with 9.9-fold elevated risk (p < 0.0001). Meanwhile, the concomitant presence of XRCC1 rs25487 with either ERCC1 rs735482 or CHRNA3 rs1051730 or both was not associated with increased risk of the disease.

Conclusion

Our results emphasize the role of gene-gene interaction in the pathogenesis of lung cancer. Large-scale further studies to clarify the underlying mechanisms are needed.

GSTM1, GSTT1 and GSTP1 Ile105Val polymorphisms in outcomes of head and neck squamous cell carcinoma patients treated with cisplatin chemoradiation

Cisplatin (CDDP) combined with radiotherapy (RT) is employed in head and neck squamous cell carcinoma (HNSCC) with variable toxicities and clinical response. Glutathione S-transferases (GSTs) participate in CDDP excretion from cells, and genes encoding GSTs, GSTM1, GSTT1and GSTP1, are polymorphic in humans. This prospective study aimed to evaluate the roles of GSTM1, GSTT1, and GSTP1 Ile105Val polymorphisms in outcomes of HNSCC patients treated with CDDP chemoradiation. Ninety patients were genotyped by multiplex PCR. Urinary CDDP measurements were performed by HPLC. Treatment side effects and response were analysed by conventional criteria. Patients with GSTT1 genes showed 7.23- and 5.37-fold higher likelihood of presenting vomiting and ototoxicity, lower glomerular filtration rate (GFR), and lower elimination of CDDP in urine relative to patients with deleted genes. Patients harbouring the GSTP1 IleVal or ValVal genotypes showed 4.28-fold higher likelihood of presenting grade 2 or 3 vomiting and lower GFR with treatment than those harbouring the IleIle genotype. In multivariate Cox analysis, patients with the GSTP1 105ValVal genotype had 3.87 more chance of presenting disease progression than those with the IleIle or IleVal genotype (p < 0.01). Our findings provide preliminary evidence that inherited abnormalities in CDDP metabolism, related to GSTT1 and GSTP1 Ile105Val polymorphisms, alter outcomes of HNSCC patients treated with CDDP and RT.

Genetic Variants as Predictive Markers for Ototoxicity and Nephrotoxicity in Patients with Locally Advanced Head and Neck Cancer Treated with Cisplatin-Containing Chemoradiotherapy (The PRONE Study)

Ototoxicity and nephrotoxicity are potentially irreversible side effects of chemoradiotherapy with cisplatin in locally advanced head and neck cancer (LAHNC) patients. Several predictive genetic variants have been described, but as yet none in LAHNC patients. The aim of this study is to investigate genetic variants as predictors for ototoxicity and nephrotoxicity in LAHNC patients treated with cisplatin-containing chemoradiotherapy. Our prospective cohort of 92 patients was genotyped for 10 genetic variants and evaluated for their association with cisplatin-induced ototoxicity (ACYP2, COMT, TPMT and WFS1) and nephrotoxicity (OCT2, MATE and XPD). Ototoxicity was determined by patient-reported complaints as well as tone audiometrical assessments. Nephrotoxicity was defined as a decrease of ≥25% in creatinine clearance during treatment compared to baseline. A significant association was observed between carriership of the A allele for rs1872328 in the ACYP2 gene and cisplatin-induced clinically determined ototoxicity (p = 0.019), and not for ototoxicity measured by tone audiometrical assessments (p = 0.449). Carriership of a T allele for rs316019 in the OCT2 gene was significantly associated with nephrotoxicity at any time during chemoradiotherapy (p = 0.022), but not with nephrotoxicity at the end of the chemoradiotherapy. In conclusion, we showed prospectively that in LAHNC patients genetic variants in ACYP2 are significantly associated with clinically determined ototoxicity. Validation studies are necessary to prove the added value for individualized treatments plans in these patients.

Role of epigenetic mechanisms in cisplatin-induced toxicity

Cisplatin (CDDP) is a highly effective antineoplastic agent, widely used in the treatment of various malignant tumors. However, its major problems are side effects associated to toxicity. Considerable inter-individual differences have been reported for CDDP-induced toxicity due to genetic and epigenetic factors. Genetic causes are well described; however, epigenetic modifications are not fully addressed. In the last few years, many evidences were found linking microRNA to the development of CDDP-mediated toxicity, particularly nephrotoxicity. In this review, we described how genetic and epigenetic modifications can be important determinants for the development of toxicity in patients treated with CDDP, and how these alterations may be interesting biomarkers for monitoring toxicity induced by CDDP. Considering the validation in different studies, we suggest that miR-34a, -146b, -378a, -192, and -193 represent an attractive study group to evaluate potential biomarkers to detect CDDP-related nephrotoxicity.

The genetic vulnerability to cisplatin ototoxicity: a systematic review

Ototoxicity is one of the major side-effects of platinum-based chemotherapy, in particular cisplatin (cis-diammine dichloroplatinum II). To our knowledge, no systematic review has previously provided a quantitative summary estimate of the impact of genetics upon the risk of developing hearing loss. We searched Embase, Medline, ASSIA, Pubmed, Scopus, and Web of Science, for studies documenting the genetic risk of ototoxicity in patients with cancer treated with cisplatin. Titles/abstracts and full texts were reviewed for inclusion. Meta-analytic estimates of risk (Odds Ratio) from the pooled data were calculated for studies that have been repeated twice or more. The search identified 3891 papers, of which 30 were included. The majority were retrospective (44%), ranging from n = 39 to n = 317, some including only patients younger than 25 years of age (33%), and some on both genders (80%). The most common cancers involved were osteosarcoma (53%), neuroblastoma (37%), prostate (17%) and reproductive (10%). Most studies performed genotyping, though only 5 studies performed genome-wide association studies. Nineteen single-nucleotide polymorphisms (SNPs) from 15 genes were repeated more than twice. Meta-analysis of group data indicated that rs1872328 on ACYP2, which plays a role in calcium homeostasis, increases the risk of ototoxicity by 4.61 (95% CI: 3.04-7.02; N = 696, p < 0.0001) as well as LRP2 rs4668123 shows a cumulated Odds Ratio of 3.53 (95% CI: 1.48-8.45; N = 118, p = 0.0059), which could not be evidenced in individual studies. Despite the evidence of heterogeneity across studies, these meta-analytic results from 30 studies are consistent with a view of a genetic predisposition to platinum-based chemotherapy mediated ototoxicity. These new findings are informative and encourage the genetic screening of cancer patients in order to identify patients with greater vulnerability of developing hearing loss, a condition having a potentially large impact on quality of life. More studies are needed, with larger sample size, in order to identify additional markers of ototoxic risk associated with platinum-based chemotherapy and investigate polygenic risks, where multiple markers may exacerbate the side-effects.

Polymorphisms in ERCC5 rs17655 and ERCC1 rs735482 Genes Associated with the Survival of Male Patients with Postoperative Oral Squamous Cell Carcinoma Treated with Adjuvant Concurrent Chemoradiotherapy

The nucleotide excision repair (NER) pathway plays a major role in the repair of DNA damaged by exogenous agents, such as chemotherapeutic and radiotherapeutic agents. Thus, we investigated the association between key potentially functional single nucleotide polymorphisms (SNPs) in the NER pathway and clinical outcomes in oral squamous cell carcinoma (OSCC) patients treated with concurrent chemoradiotherapy (CCRT). Thirteen SNPs in five key NER genes were genotyped in 319 male OSCC patients using iPLEX MassARRAY. Cox proportional hazards models and Kaplan–Meier survival curves were used to estimate the risk of death or recurrence. Carriers of the XPC rs2228000 TT genotype showed a borderline significant increased risk of poor overall survival under the recessive model (hazard ratio (HR) = 1.81, 95% confidence interval (CI) = 0.99–3.29). The CC genotypes of ERCC5 rs17655 (HR = 1.54, 95% CI = 1.03–2.29) and ERCC1 rs735482 (HR = 1.65, 95% CI = 1.06–2.58) were associated with an increased risk of worse disease-free survival under the recessive model. In addition, participants carrying both the CC genotypes of ERCC5 rs17655 and ERCC1 rs735482 exhibited an enhanced susceptibility for recurrence (HR = 2.60, 95% CI = 1.11–6.09). However, no statistically significant interaction was observed between them. Our findings reveal that the ERCC5 rs17655 CC and ERCC1 rs735482 CC genotypes were associated with an increased risk of recurrence in male patients with OSCC treated with CCRT. Therefore, CCRT may not be beneficial, and alternative treatments are required for such patients.

Association between genetic polymorphisms and platinum-induced ototoxicity in children

Platinum is extensively used in the treatment of several childhood cancers. However, ototoxicity is one of the most notable adverse effects, especially in children. Several studies suggest that genetics may predict its occurrence. Here, polymorphisms associated with platinum-induced ototoxicity were selected from the literature and were investigated in a pediatric population treated with platinum-based agents. In this retrospective study, patients treated with cisplatin and/or carboplatin were screened. The patients with pre- and post-treatment audiogram (Brock criteria) available were included. We selected polymorphisms that have previously been associated with cisplatin ototoxicity with a minor allele frequency ≥30%. Deletion of GSTM1 and GSTT1, rs1799735 (GSTM3), rs1695 (GSTP1), rs4880 (SOD2), rs2228001 (XPC), rs1799793 (XPD) and rs4788863 (SLC16A5) were investigated. Data of one hundred and six children matching the eligible criteria were analyzed. Thirty-three patients (31%) developed ototoxicity (with a Brock grade ≥2). The probability of hearing loss increased significantly in patients carrying the null genotype for GSTT1 (P = 0.03), A/A genotype at rs1695 (P = 0.01), and C/C genotype at rs1799793 (P = 0.008). We also showed an association of the cumulative doses of carboplatin with cisplatin ototoxicity (P <0.05). To conclude, deletion of GSTT1, rs1695 and rs1799793 may constitute potential predictors of platinum-induced ototoxicity.

Single nucleotide polymorphisms in DNA repair genes and putative cancer risk

Single nucleotide polymorphisms (SNPs) are the most frequent type of genetic alterations between individuals. An SNP located within the coding sequence of a gene may lead to an amino acid substitution and in turn might alter protein function. Such a change in protein sequence could be functionally relevant and therefore might be associated with susceptibility to human diseases, such as cancer. DNA repair mechanisms are known to play an important role in cancer development, as shown in various human cancer syndromes, which arise due to mutations in DNA repair genes. This leads to the question whether subtle genetic changes such as SNPs in DNA repair genes may contribute to cancer susceptibility. In numerous epidemiological studies, efforts have been made to associate specific SNPs in DNA repair genes with altered DNA repair and cancer. The present review describes some of the common and most extensively studied SNPs in DNA repair genes and discusses whether they are functionally relevant and subsequently increase the likelihood that cancer will develop.