Polymorphisms in ERCC1, GSTs, TS and MTHFR predict clinical outcomes of gastric cancer patients treated with platinum/5-Fu-based chemotherapy: a systematic review

Genetic Polymorphisms in Glutathione S-Transferase (GST) Gene and Their Correlation with Toxicity of Chemotherapy in Breast Cancer Patients

BACKGROUND

Glutathione S-Transferase (GST) is a family of phase II metabolizing enzymes contribute to detoxification and elimination of variety of endogenous as well as exogenous xenobiotics including chemotherapeutic agents. The comprehensive knowledge on the impact of genetic polymorphisms in GST) enzyme coding gene will help to understand the clinical outcomes in breast cancer patients treated with either Adriamycin or paclitaxel or combination of both. In this study we attempted to assess the genetic polymorphisms in GSTM1, GSTT1, GSTP1 and their association with Adriamycin and Paclitaxel induced toxicity reactions in breast cancer patients.

METHODS

Two hundred BC patients receiving Adriamycin and Paclitaxel chemotherapy were enrolled in this study and chemotherapy induced hematological and non-hematological toxicity reactions were noted. The polymorphisms in GSTM1, GSTP1 and GSTT1 gene were studied by PCR and RFLP analysis.

RESULTS

After the univariate analysis of the genetic polymorphisms of GSTM1, GSTP1 and GSTT1 showed that GSTT1 null genotype showed significant association with neutropenia (OR=2.84, 95% CI: 1.06-7.56; p=0.036) in breast cancer patients treated with Adriamycin and GSTT1 null genotype in patients with >1 CINV toxicity confirmed significant correlation (OR=3.75, 95% CI: 1.46-9.59; p=0.005). The genetic polymorphisms of GSTP1 (exon 5) A/G heterozygous genotype was significant in grade >1 toxicity reactions of mucositis (OR=3.22, 95% CI: 1.06-9.71; p=0.037) in breast cancer patients administered with Paclitaxel chemotherapy.

CONCLUSION

The findings obtained from this study proposed significant involvement of GSTT1-null genotype in hematological neutropenia toxicity in response to Adriamycin and GSTM1-null genotype showed negative association with non-hematological toxicity (bodyache) in response to Paclitaxel.

Metabolomic analysis of circulating tumor cells derived liver metastasis of colorectal cancer

Metabolic reprogramming is one of the essential features of tumor that may dramatically contribute to metastasis and collapse. The metabolic profiling is investigated on the patient derived tissue and cancer cell line derived mouse metastasis xenograft. As well-recognized "seeds" for remote metastasis of tumor, role of circulating tumor cells (CTCs) in the study of metabolic reprogramming feature of tumor is yet to be elucidated. More specifically, whether there is difference of metabolic features of liver metastasis in colorectal cancer (CRC) derived from either CTCs or cancer cell line is still unknown. In this study, comprehensive untargeted metabolomics was performed using high performance liquid chromatography-mass spectrometry (HPLC-MS) in liver metastasis tissues from CT26 cells and CTCs derived mouse models. We identified 288 differential metabolites associated with the pathways such as one carbon pool by folate, folate biosynthesis and histidine metabolism through bioinformation analysis. Multiple gene expression was upregulated in the CTCs derived liver metastasis, specifically some specific enzymes. These results indicated that the metabolite phenotype and corresponding gene expression in the CTCs derived liver metastasis tissues was different from the parental CT26 cells, displaying a specific up-regulation of mRNAs involved in the above metabolism-related pathways. The metabolic profile of CTCs was characterized on the liver metastatic process in colorectal cancer. The invasion ability and chemo drug tolerance of the CTCs derived tumor and metastasis was found to be overwhelming higher than cell line derived counterpart. Identification of the differential metabolites will lead to a better understanding of the hallmarks of the cancer progression and metastasis, which may suggest potential attractive target for treating metastatic CRC.

Targeting purine metabolism in ovarian cancer

Purine, an abundant substrate in organisms, is a critical raw material for cell proliferation and an important factor for immune regulation. The purine de novo pathway and salvage pathway are tightly regulated by multiple enzymes, and dysfunction in these enzymes leads to excessive cell proliferation and immune imbalance that result in tumor progression. Maintaining the homeostasis of purine pools is an effective way to control cell growth and tumor evolution, and exploiting purine metabolism to suppress tumors suggests interesting directions for future research. In this review, we describe the process of purine metabolism and summarize the role and potential therapeutic effects of the major purine-metabolizing enzymes in ovarian cancer, including CD39, CD73, adenosine deaminase, adenylate kinase, hypoxanthine guanine phosphoribosyltransferase, inosine monophosphate dehydrogenase, purine nucleoside phosphorylase, dihydrofolate reductase and 5,10-methylenetetrahydrofolate reductase. Purinergic signaling is also described. We then provide an overview of the application of purine antimetabolites, comprising 6-thioguanine, 6-mercaptopurine, methotrexate, fludarabine and clopidogrel. Finally, we discuss the current challenges and future opportunities for targeting purine metabolism in the treatment-relevant cellular mechanisms of ovarian cancer.

Molecular Bases of Mechanisms Accounting for Drug Resistance in Gastric Adenocarcinoma

Gastric adenocarcinoma (GAC) is the most common histological type of gastric cancer, the fifth according to the frequency and the third among the deadliest cancers. GAC high mortality is due to a combination of factors, such as silent evolution, late clinical presentation, underlying genetic heterogeneity, and effective mechanisms of chemoresistance (MOCs) that make the available antitumor drugs scarcely useful. MOCs include reduced drug uptake (MOC-1a), enhanced drug efflux (MOC-1b), low proportion of active agents in tumor cells due to impaired pro-drug activation or active drug inactivation (MOC-2), changes in molecular targets sensitive to anticancer drugs (MOC-3), enhanced ability of cancer cells to repair drug-induced DNA damage (MOC-4), decreased function of pro-apoptotic factors versus up-regulation of anti-apoptotic genes (MOC-5), changes in tumor cell microenvironment altering the response to anticancer agents (MOC-6), and phenotypic transformations, including epithelial-mesenchymal transition (EMT) and the appearance of stemness characteristics (MOC-7). This review summarizes updated information regarding the molecular bases accounting for these mechanisms and their impact on the lack of clinical response to the pharmacological treatment currently used in GAC. This knowledge is required to identify novel biomarkers to predict treatment failure and druggable targets, and to develop sensitizing strategies to overcome drug refractoriness in GAC.

Glutathione S-transferases genes variants and chemotherapy efficacy in gastrointestinal cancer patients: a meta-analysis based on 50 pharmacogenetic studies

Background: The role of glutathione s-transferase genes (GSTP1, GSTM1 and GSTT1) variants and the GSTP1 expression level on chemotherapy efficacy of gastrointestinal cancer (GIC) patients were inconsistent. Methods: A meta-analysis about GSTP1, GSTM1 and GSTT1 variants and the GSTP1 expression level on chemotherapy efficacy of GIC patients was performed using data from PubMed, PMC, EMBASE, Web of Science, and Wanfang database. Results: Our meta-analysis enrolled 50 publications including 6518 patients. We found that patients with GIC harboring GSTP1 (IIe105Val) Val locus had higher objective response rates (ORR) than the IIe/IIe genotypic patients (odds ratio (OR) = 1.580, 95% confidence interval (CI) = 1.159-2.154, P = 0.004). Significant associations were found between the Ile105Val variant and overall survival of Caucasian GIC patients (IIe/Val vs. IIe/IIe: OR = 0.797 (0.674-0.944), P = 0.009). Caucasian GIC patients and gastric cancer patients with GSTT1 null genotype had worse response rates compared to GSTT1 present patients (OR = 0.530 (0.356-0.789), P = 0.002; OR = 0.643 (0.463-0.895), P = 0.009, respectively). Conclusion: This meta-analysis illustrates that GSTP1 IIe105Val and GSTT1 null/present variants could be useful predictors of chemotherapy efficacy in patients with gastrointestinal cancer.

Methylomic changes in response to micronutrient supplementation and MTHFR genotype

Exposure times and dosage required for dietary components to modify DNA methylation patterns are largely unknown.

AIM

This exploratory research represents the first genome-wide analysis of DNA methylation changes during a randomized-controlled-trial (RCT) for dietary supplementation with broad spectrum vitamins, minerals and amino acids in humans.

METHODS

Genome-wide changes in methylation from paired, peripheral blood samples were assessed using the Infinium Methylation EPIC 850 K array.

RESULTS

Methylation increased at 84% of the most significant differentially methylated CpGs; however, none showed significance after adjustment for genome-wide testing.

CONCLUSION

Micronutrient supplementation is unlikely to have a substantial biological effect on DNA methylation over 10 weeks; however, the trend toward hypermethylation that we observed is likely to become more marked with longer exposure periods.

Effects of gene polymorphisms on the risk of severe hyponatremia during DCF chemotherapy for patients with esophageal squamous cell carcinoma

Combination chemotherapy using docetaxel, cisplatin and 5-fluorouracil (DCF) is a promising treatment option for patients with advanced esophageal squamous cell carcinoma (ESCC), although its clinical application is limited by severe systemic toxicities. There are no validated markers for predicting the adverse effects caused by this regimen. This pharmacogenetic study enrolled 57 patients with chemotherapy-naive advanced ESCC between July 2012 and March 2016 (UMIN000008462). All patients received at least one course of DCF chemotherapy (docetaxel, 60 mg/m² on day 1; cisplatin, 70 mg/m² on day 1; 5-fluorouracil, 600 mg/m² on days 1-5). The associations between four gene polymorphisms (ERCC1 rs11615, GSTP1 rs1695, TYMS rs151264360 and XPD rs13181) and the development of grade 3/4 adverse events during the first course of chemotherapy were prospectively investigated. The patients had a median age of 66 years (range, 45-77 years) and the majority were male (51 males vs. 6 females). The treatment settings were neoadjuvant (47 patients), adjuvant (1 patient) and salvage (9 patients), with dose intensities of 100% (51 patients) or 80% (6 patients). The severe adverse events were leukopenia (70.2%), neutropenia (86.0%), febrile neutropenia (36.8%), acute kidney injury (29.1%) and hyponatremia (43.9%). Two polymorphisms were independently associated with the development of severe hyponatremia among patients carrying the minor allele (vs. patients with major homozygote genotype): TYMS 3'-UTR rs151264360 (odds ratio, 3.64; 95% confidence interval, 1.11-11.9) and XPD Lys751Gln rs13181 (odds ratio, 10.1; 95% confidence interval, 1.10-93.3). Therefore, the presence of the TYMS and XPD polymorphisms may aid in identifying patients with a high risk of developing severe hyponatremia during DCF chemotherapy.

Relevance of methylenetetrahydrofolate reductase gene variants C677T and A1298C with response to fluoropyrimidine-based chemotherapy in colorectal cancer: a systematic review and meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme influencing the metabolism of fluoropyrimidines. The relevance of MTHFR polymorphisms with the clinical response to fluoropyrimidine-based chemotherapy has been explored, but the results remain controversial. Thus, a meta-analysis was performed to provide a comprehensive estimate in this account. Relevant studies were identified through PubMed, Embase and Web of Science databases from inception up to May 2017. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were applied to assess the strength of association. A total of 2118 colorectal cancer patients from 21 studies were included in the meta-analysis. Overall, there was no significant association between MTHFR C677T (rs1801133) or A1298C (rs1801131) polymorphisms and the clinical response to fluoropyrimidine-based chemotherapy under all of the three genetic models (allele model, dominant model, and recessive model) and stratification analysis, except for the retrospective study subgroup in the dominant model of MTHFR C677T and the “5-Fu + FA” treatment group in the allele contrast of MTHFR A1298C. No or moderate heterogeneity was observed in all genetic models. This meta-analysis suggested that MTHFR polymorphisms could not be considered as reliable factors for predicting the clinical response to fluoropyrimidine-based chemotherapy in colorectal cancer patients.

Relevance of MTHFR polymorphisms with response to fluoropyrimidine-based chemotherapy in oesophagogastric cancer: a meta-analysis

OBJECTIVE

To evaluate the association between methylenetetrahydrofolate reductase (MTHFR) polymorphisms and the response to fluoropyrimidine-based chemotherapy in oesophagogastric cancer.

DESIGN

Meta-analysis.

METHODS

We searched PubMed, Embase and Web of Science databases from inception up to October 2017 for relevant studies. The statistical analysis was performed using STATA V.12.0 software. The pooled ORs and 95% CIs were used to assess the strength of the association under the allele, dominant and recessive models. We also conducted subgroup analysis stratified by cancer type, ethnicity and study design. Additionally, the sensitivity analysis was performed by sequential omission of individual studies, and the publication bias was detected using both Begg's test and Egger's test.

RESULTS

A total of 2020 patients from 12 studies were included in this meta-analysis. The results showed that there was no significant association between MTHFR C677T (rs1801133) and A1298C (rs1801131) polymorphisms and the clinical response to fluoropyrimidine-based chemotherapy under all of the three genetic models (T vs C: OR 0.93, 95% CI 0.76 to 1.15; C vs A: OR 0.88, 95% CI 0.56 to 1.40. CT+TT vs CC: OR 0.94, 95% CI 0.72 to 1.23; AC+CC vs AA: OR 0.80, 95% CI 0.47 to 1.35. TT vs CC+CT: OR 1.02, 95% CI 0.74 to 1.39; CC vs AA+AC: OR 1.15, 95% CI 0.50 to 2.67). When stratified by cancer type, ethnicity or study design, the association was still not significant in all subgroups.

CONCLUSIONS

This meta-analysis suggested that MTHFR polymorphisms could not be considered as reliable factors for predicting the response to fluoropyrimidine-based chemotherapy in oesophagogastric cancer.

SNPs in predicting clinical efficacy and toxicity of chemotherapy: walking through the quicksand

In the "precision medicine" era, chemotherapy still remains the backbone for the treatment of many cancers, but no affordable predictors of response to the chemodrugs are available in clinical practice. Single nucleotide polymorphisms (SNPs) are gene sequence variations occurring in more than 1% of the full population, and account for approximately 80% of inter-individual genomic heterogeneity. A number of studies have investigated the predictive role of SNPs of genes enrolled in both pharmacodynamics and pharmacokinetics of chemotherapeutics, but the clinical implementation of related results has been modest so far. Among the examined germline polymorphic variants, several SNPs of dihydropyrimidine dehydrogenase (DPYD) and uridine diphosphate glucuronosyltransferases (UGT) have shown a robust role as predictors of toxicity following fluoropyrimidine- and/or irinotecan-based treatments respectively, and a few guidelines are mandatory in their detection before therapy initiation. Contrasting results, however, have been reported on the capability of variants of other genes as MTHFR, TYMS, ERCC1, XRCC1, GSTP1, CYP3A4/3A5 and ABCB1, in predicting either therapy efficacy or toxicity in patients undergoing treatment with pyrimidine antimetabolites, platinum derivatives, irinotecan and taxanes. While formal recommendations for routine testing of these SNPs cannot be drawn at this moment, therapeutic decisions may indeed benefit of germline genomic information, when available. Here, we summarize the clinical impact of germline genomic variants on the efficacy and toxicity of major chemodrugs, with the aim to facilitate the therapeutic expectance of clinicians in the odiern quicksand field of complex molecular biology concepts and controversial trial data interpretation.

A Meta-Analysis: Methylenetetrahydrofolate Reductase C677T Polymorphism in Gastric Cancer Patients Treated with 5-Fu Based Chemotherapy Predicts Serious Hematologic Toxicity but Not Prognosis

5-fluorouracil (5-Fu) metabolism associated enzyme, methylenetetrahydrofolate reductase (MTHFR)'s polymorphism C677T can affect enzyme activity and a series of studies have been performed to examine the association of this MTHFR polymorphism with the clinical outcomes of gastric cancer (GC) patients treated with 5-Fu based chemotherapies. However, the results are inconsistent and inconclusive. Therefore, a more comprehensive summary like meta-analysis on this topic is needed. We performed a systematic literature search of PubMed and Embase up to May 20, 2017. Researches exploring MTHFR polymorphisms C677T's relationship with the clinical outcomes (response rate, overall survival and toxicity) of GC patients treated with 5-Fu based chemotherapy were included. The association was measured by odds ratios (ORs) or hazard ratios (HRs) combined with their 95% confidence intervals (CIs) using random/fixed effects model according to the studies' heterogeneity. Subgroup, sensitivity and publication bias analyses were conducted. Thirteen studies were finally included in this meta-analysis. No significant association was found between response rate [TT/ (CC+CT) OR=1.31, 95% CI: 0.62-2.76] or overall survival [(CT+TT)/CC HR=1.05, 95% CI: 0.86-1.26; TT/(CT+CC) HR=1.48, 95% CI: 0.53-4.15] and MTHFR polymorphism C677T. However, GC patients with CC or CT genotype tended to experience less severe hematologic toxicity than those with TT genotype [(CC+CT)/TT OR=0.66, 95% CI: 0.48-0.91]. In conclusion, MTHFR C677T polymorphism predicts severe hematologic toxicity in GC patients receiving 5-Fu based chemotherapy, but not the efficiency.

ABCC2-24C > T polymorphism is associated with the response to platinum/5-Fu-based neoadjuvant chemotherapy and better clinical outcomes in advanced gastric cancer patients

Several studies have evaluated the efficacy of neoadjuvant treatment using oxaliplatin and fluoropyrimidines in advanced gastric cancer (GC). However, preoperative biomarkers predictive of clinical outcome remain lacking. We examined polymorphisms in the MTHFR, DPYD, UMPS, ABCB1, ABCC2, GSTP1, ERCC1, and XRCC1 genes to evaluate their usefulness as pharmacogenetic markers in a cohort of 103 GC patients treated with preoperative chemotherapy. DNA was extracted from peripheral blood cells, and the genotypes were analyzed using a SNaPShot^TM assay, polymerase chain reaction amplification, and sequencing. The ABCC2-24C > T (rs717620) genotype was associated with pathologic response to neoadjuvant chemotherapy. Patients with the TT and TC genotypes responded to neoadjuvant chemotherapy 3.80 times more often than those with the CC genotype (95% CI: 1.27–11.32). Patients with the CC genotype also had poorer outcomes than those with other genotypes. Thus, ABCC2-24C > T polymorphism may help to predict the response to preoperative chemotherapy in GC patients.

Pharmacogenetic Analysis of the UK MRC (Medical Research Council) MAGIC Trial: Association of Polymorphisms with Toxicity and Survival in Patients Treated with Perioperative Epirubicin, Cisplatin, and 5-fluorouracil (ECF) Chemotherapy

Purpose: Germline polymorphisms may affect chemotherapy efficacy and toxicity. We examined the effect of polymorphisms in drug metabolism and DNA repair genes on pathologic response rates, survival, and toxicity for patients randomized to surgery alone or perioperative ECF chemotherapy in the MRC MAGIC trial.Experimental Design: DNA was extracted from nontumor resection formalin-fixed paraffin-embedded (FFPE) blocks. ERCC1, ERCC2, XRCC1, DYPD, and OPRT SNPs were evaluated using Sequenom, GSTP1, GSTT1 deletion, and TYMS (TS) 5' 2R/3R using multiplex PCR. Post PCR amplification, TS 2R/3R and GSTT1 samples underwent gel electrophoresis.Results: Polymorphism data were available for 289 of 456 (63.4%) operated patients. No polymorphism was statistically significantly associated with pathologic response to chemotherapy. Median overall survival (OS) for patients treated with surgery alone with any TS genotype was not different (1.76 years 2R/2R, 1.68 years 2R/3R, 2.09 years 3R/3R). Median OS for patients with a TS 2R/2R genotype treated with chemotherapy was not reached, whereas median OS for 2R/3R and 3R/3R patients were 1.44 and 1.60 years, respectively (log rank P value = 0.0053). The P value for the interaction between treatment arm and genotype (3R/3R and 3R/2R vs. 2R/2R) was 0.029. No polymorphism was statistically significantly associated with chemotherapy toxicity.Conclusions: In MAGIC, patients with a TS 2R/2R genotype appeared to derive a larger benefit from perioperative ECF chemotherapy than patients with 3R containing genotypes. Further exploration of this potential predictive biomarker in this patient population is warranted. Clin Cancer Res; 23(24); 7543-9. ©2017 AACR.

GSTP1 polymorphism predicts treatment outcome and toxicities for breast cancer

This study aimed to investigate the association of the GSTP1 gene polymorphism with the outcomes and toxicities of treatments in breast cancer. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for the association of GSTP1 polymorphism with tumour response and toxicities, and the hazard ratios (HRs) and 95% CIs were calculated for the association between GSTP1 polymorphism and overall survival (OS). The statistical analysis showed that the GSTP1 polymorphism was not associated with tumour response or OS. A significant increase in the incidence of toxicities was observed (GA vs. AA OR = 1.45, 95% CI = 1.04–2.01, P = 0.028; GG vs. AA OR = 1.47, 95% CI = 1.03–2.10, P = 0.036; recessive model OR = 1.54, 95% CI = 1.13–2.09, P = 0.006; and allele model OR = 1.35, 95% CI = 1.07–1.71, P = 0.011), especially in the chemotherapy ± surgery group (GA vs. AA OR = 1.64, 95% CI = 1.05–2.56, P = 0.030; recessive model OR = 1.72, 95% CI = 1.17–2.54, P = 0.006; and allele model OR = 1.57, 95% CI = 1.11–2.21, P = 0.010). Our results indicate that the GSTP1 polymorphism may be associated with increased toxicity, especially in patients treated with chemotherapy ± surgery.

Lethal hepatotoxicity following 5-fluorouracil/cisplatin chemotherapy: a relevant case report

Some articles have reported severe toxicities induced by cisplatin/5-fluorouracil regimens, nevertheless, severe and lethal liver toxicity has not been previously reported. In this article, we report the case of a 72-year-old woman, who developed fulminant hepatitis, hypoglycemia and hypotension with atrial fibrillation not responding to treatment. After ruling out all other possible causes of hepatitis, the toxicity was more likely attributed to 5-fluorouracil. Genotyping was performed and the patient was found to be a homozygote carrier of the T variant of the MTHFR gene. The patient died two days later. Several factors, including genetic factors, could explain this severe toxicity. The present case discusses the importance of personalized medicine in oncology based on pharmacogenetic analysis of polymorphisms.

Predictive role of host constitutive variants in neoadjuvant therapy of esophageal cancer

Chemoradiotherapy followed by surgery is at present the standard therapeutic approach for esophageal cancer (EC) in patients with resectable tumor. However, response to neoadjuvant therapy is characterized by a strong interpatient variability, and the identification of markers predictive of outcome is mandatory. In this review, taking into account the currently available literature, we report the impact that host genetic variables can have on EC neoadjuvant therapy. We mainly focused on the gene variants involved in the pharmacokinetics and pharmacodynamics of the common chemotherapeutic drugs used to treat EC patients, commented on the weakness of the present knowledge, and discussed the future strategies to achieve a more personalized and effective EC treatment.

Predictive value of GSTP1 Ile105Val polymorphism in clinical outcomes of chemotherapy in gastric and colorectal cancers: a systematic review and meta-analysis

PURPOSE

Gastric and colorectal cancers remain the major causes of cancer-related death with a bad prognosis. Up to now, platinum combined with fluoropyrimidines has been most commonly used in chemotherapy regimens of gastric and colorectal cancers. Recently, a series of studies have been conducted to investigate the associations of biomarkers, such as GSTP1 Ile105Val polymorphism, with the chemotherapy efficacy in gastric and colorectal cancers; however, the results were not consistent and inconclusive. Here, we performed a systematic review and meta-analysis to summarize the associations of GSTP1 Ile105Val polymorphism with the chemotherapy efficacy in gastric and colorectal cancers.

METHODS

A systematic review was conducted to search relevant studies in English databases (PubMed, ISI Web of Science, and EMBASE) up to November 30, 2015. The pooling ORs or HRs were used to assess the strength of the associations of GSTP1 Ile105Val polymorphism with clinical outcomes such as tumor response, toxicity, progression-free survival (PFS), and overall survival (OS).

RESULTS

Forty-one papers containing 8169 cases were finally included in the present meta-analysis study. Of which, 28 articles were performed in colorectal cancers, one in gastrointestinal carcinoma (gastric and colon cancer), 11 in gastric cancers, and one in colorectal and gastroesophageal cancers. After pooling all the eligible studies, we identified significant associations of GSTP1 Ile105Val polymorphism with chemotherapy-related tumor response (G vs. A: OR 1.697, 95 % CI 1.191-2.418; GG vs. AA: OR 2.804, 95 % CI 1.414-5.560; AG vs. AA: OR 1.540, 95 % CI 1.011-2.347; GG vs. AAAG: OR 2.139, 95 % CI 1.256-3.641), PFS (GG vs. AA, HR 0.640, 95 % CI 0.455-0.900; AGGG vs. AA: HR 0.718, 95 % CI 0.562-0.919), and OS (AG vs. AA: HR 0.857, 95 % CI 0.746-0.986; GG vs. AA: HR 0.679, 95 % CI 0.523-0.882; AGGG vs. AA: HR 0.663, 95 % CI 0.542-0.812) in gastric and colorectal cancers and no significant association was found between the polymorphism with toxicity.

CONCLUSIONS

GSTP1 Ile105Val polymorphism was associated with tumor response, PFS, and OS in gastric and colorectal cancers after chemotherapy.

Lauren classification and individualized chemotherapy in gastric cancer

Gastric cancer is one of the most common malignancies worldwide. During the last 50 years, the histological classification of gastric carcinoma has been largely based on Lauren's criteria, in which gastric cancer is classified into two major histological subtypes, namely intestinal type and diffuse type adenocarcinoma. This classification was introduced in 1965, and remains currently widely accepted and employed, since it constitutes a simple and robust classification approach. The two histological subtypes of gastric cancer proposed by the Lauren classification exhibit a number of distinct clinical and molecular characteristics, including histogenesis, cell differentiation, epidemiology, etiology, carcinogenesis, biological behaviors and prognosis. Gastric cancer exhibits varied sensitivity to chemotherapy drugs and significant heterogeneity; therefore, the disease may be a target for individualized therapy. The Lauren classification may provide the basis for individualized treatment for advanced gastric cancer, which is increasingly gaining attention in the scientific field. However, few studies have investigated individualized treatment that is guided by pathological classification. The aim of the current review is to analyze the two major histological subtypes of gastric cancer, as proposed by the Lauren classification, and to discuss the implications of this for personalized chemotherapy.

A meta-analysis identifies ERCC1 gene polymorphism as a predictor of better patient response to treatment with radiochemotherapy

PURPOSE

This meta-analysis aimed to evaluate whether an association exists between the ERCC1 rs11615 (C>T) polymorphism and patient response to platinum-based chemotherapy and radiation-based chemotherapy.

METHODS

Publications were selected from PubMed and MEDLINE. A meta-analysis was conducted to determine the association between genetic polymorphisms and response to platinum-based chemotherapy and radiation-based chemotherapy by checking the odds ratios (ORs) and 95 % confidence intervals (CIs).

RESULTS

In our overall analysis, the ERCC1 rs11615 (C>T) polymorphism was not associated with response to platinum-based chemotherapy in five comparison models. In the subgroup analyses by ethnicity, the ERCC1 rs11615 (C>T) polymorphism was shown to be significantly associated with objective response in Caucasian patients treated with platinum-based chemotherapy in the recessive model (TT vs.

CT/CC

OR 0.696, 95 % CI 0.508-0.954, heterogeneity = 0.330), but the association was not observed in the Asian population. The C allele was significantly associated with better response to radiochemotherapy in the recessive model comparison (TT vs.

CC/CT

OR 0.724, 95 % CI 0.585-0.869, heterogeneity = 0.008). Subgroup analysis by cancer type revealed that the C allele of ERCC1 rs11615 predicted a better response in esophageal cancers in two comparison models (T vs. C: OR 0.756, 95 % CI 0.648-0.880, heterogeneity = 0.653; TT vs.

TC/CC

OR 0.457, 95 % CI 0.306-0.684, heterogeneity = 0.723). Stratified analysis by ethnicity showed a better response in Caucasians in allelic comparison model (T vs. C: OR 0.895, 95 % CI 0.819-0.977, heterogeneity = 0.095).

CONCLUSION

Together, our results suggest that the ERCC1 rs11615 (C>T) polymorphism was associated with therapeutic response in Caucasian patients and C allele of ERCC1 rs11615 could represent a genetic molecular marker to predict better patient response to radiochemotherapy in recessive model. However, larger prospective randomized trials will be required.

Fluoropyrimidine and platinum toxicity pharmacogenetics: an umbrella review of systematic reviews and meta-analyses

Fluoropyrimidine (FU) and platinum-based chemotherapies are greatly complicated by their associated toxicities. This umbrella systematic review synthesized all systematic reviews that investigated associations between germline variations and toxicity, with the aim of informing personalized medicine. Systematic reviews are important in pharmacogenetics where false positives are common. Four systematic reviews were identified for FU-induced toxicity and three for platinum. Polymorphisms of DPYD and TYMS, but not MTHFR, were statistically significantly associated with FU-induced toxicity (although only DPYD had clinical significance). For platinum, GSTP1 was found to not be associated with toxicity. This umbrella systematic review has synthesized the best available evidence on the pharmacogenetics of FU and platinum toxicity. It provides a useful reference for clinicians and identifies important research gaps.

GSTT1 and GSTM1 polymorphisms predict treatment outcome for breast cancer: a systematic review and meta-analysis

Observational studies have reported controversial results on the association between GSTT1 and GSTM1 genotypes and treatment outcome of breast cancer. The purpose of this study is to evaluate the association between GSTT1 and GSTM1 and treatment outcome in breast cancer patients. Eligible studies were searched in PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure databases. A random-effect model or fixed-effect model was used to calculate the overall combined risk estimates. Twenty-one studies with a total of 4990 patients were included in this meta-analysis. The GSTM1 null genotype (odds ratio (OR) = 1.33, 95 % confidence interval (CI) 1.01-1.75, P = 0.046) and GSTT1/GSTM1 double null genotype (OR = 2.22, 95 % CI 1.02-4.84, P = 0.045) were significantly associated with an increased tumor response. A reduced overall survival (hazard ratio (HR) = 0.84, 95 % CI 0.72-0.98, P = 0.024) was observed in GSTM1 null genotype, especially in mixed descent (HR = 0.77, 95 % CI 0.61-0.96, P = 0.018) and large sample size (HR = 0.85, 95 % CI 0.72-0.99, P = 0.033). Evidence of publication bias was observed in GSTM1 genotype rather than in GSTT1 genotype. This meta-analysis suggests that GSTM1 null and GSTT1/GSTM1 double null polymorphisms might be significantly associated with an increased tumor response. However, the GSTM1 null genotype might be significantly associated with a reduced overall survival. Future studies are warranted to confirm these findings.

Influences of ERCC1, ERCC2, XRCC1, GSTP1, GSTT1, and MTHFR polymorphisms on clinical outcomes in gastric cancer patients treated with EOF chemotherapy

This study investigated the associations between genetic polymorphisms of six genes involved in DNA repair, detoxification pathways, and fluoropyrimidine metabolism and clinical outcomes in MGC patients receiving EOF treatment. This retrospective study included 108 Chinese MGC patients receiving EOF as first-line chemotherapy. Nine single nucleotide polymorphisms (SNPs) of six genes (ERCC1 rs2298881, ERCC2 rs13181 and rs1799793, XRCC1 rs25487 and rs25489, GSTP1 rs1695, GSTT1 rs2266637, and MTHFR rs1801133 and rs1801131) were genotyped, and the associations between each SNP and clinical outcome were analyzed. XRCC1 rs25487 A allele was significantly associated with progression disease (PD) to EOF (p = 0.002), and patients with AA genotype had significantly poorer progression-free survival (PFS) (p = 0.001) and overall survival (OS) (p = 0.041) compared with patients with the G allele (GG + GA). ERCC2 rs13181 G allele was significantly associated with PD (p = 0.026), and G carriers (GG + GT) tended to have poorer PFS (p = 0.092) than TT homozygotes. ERCC2 rs1799793 GA genotype was associated with unfavorable PFS (p = 0.034) and a tendency toward poorer OS (p = 0.090) compared with GG homozygotes. Patients were categorized as either good (0 risk factors) or poor risk (≥1 unfavorable SNPs) using a prognostic index based on XRCC1 rs25487 AA, ERCC2 rs13181 (GG + GT), and ERCC2 rs1799793 GA genotypes, with median OS and PFS of 534 days, 281 days (p = 0.009) and 206 days, and 123 days (p < 0.001), respectively. These results suggest that the prognostic index comprising XRCC1 rs25487, ERCC2 rs13181, and rs1799793 polymorphisms may be a useful predictor of clinical outcomes in MGC treated with EOF.

A meta-analysis of glutathione S-transferase M1 and T1 genetic polymorphism in relation to susceptibility to nasopharyngeal carcinoma

OBJECTIVE

To investigate the relationship between glutathione S-transferase M1 (GSTM1), and T1 (GSTT1) genetic polymorphism and susceptibility to nasopharyngeal carcinoma (NPC) using meta-analysis method.

METHODS

Data of published case-control studies on the relationship between GSTT1, GSTM1 genetic polymorphism and susceptibility to NPC were collected from EMBASE, PubMed, Web of Science, China Academic Journals Full-text Database, Chinese Biomedical Literature Database, and Wanfang Database. Meta-analysis was conducted using Revman 5.2 software.

RESULTS

Nine studies were included for meta-analysis with a total of 1295 cases of NPC patients and 1967 control individuals. Meta-analysis showed that the risk of NPC was significantly higher in population with GSTM1 gene deletion (OR=1.43, 95% CI: 1.42-1.65; P<0.001). Similarly, the risk of NPC was significantly higher in Chinese population with GSTM1 gene deletion (OR=1.38, 95% CI: 1.18-1.62; P<0.001). We did not find association between GSTT1 gene deletion and NPC risk not only in total population (OR=1.32, 95% CI: 0.92-1.87; P=0.12), but in Chinese population (OR=1.41, 95% CI: 0.97-2.04; P=0.07).

CONCLUSION

GSTM1 genetic polymorphism, but GSTT1, is associated with susceptibility to NPC.

Association between the ERCC1 rs11615 polymorphism and clinical outcomes of oxaliplatin-based chemotherapies in gastrointestinal cancer: a meta-analysis

Purpose

The relationship between the excision repair cross-complementing 1 (ERCC1) rs11615 polymorphism (C/T) and responses to oxaliplatin-based chemotherapy for gastric cancer (GC) and colorectal cancer (CRC) patients is controversial. Therefore, we performed a meta-analysis to assess this relationship.

Method

Relevant studies were retrieved by searching the PubMed database. A systematic review and meta-analysis was performed to evaluate the predictive value of the ERCC1 rs11615 polymorphism for the clinical outcomes of GC and CRC patients receiving oxaliplatin-based chemotherapy. Therapeutic response to chemotherapy, progression-free survival (PFS), and overall survival (OS) were analyzed.

Results

A total of 22 studies were included in this meta-analysis, including 1,242 cases of GC and 1,772 cases of CRC. For the ERCC1 rs11615 polymorphism, the T allele was associated with a reduced response to chemotherapy in Asians and GC patients (P<0.05). On the other hand, the T allele was associated with a significant increase in the risk for shorter PFS and OS in all patients (PFS: hazard ratio [HR] =1.22, P<0.001, 95% confidence interval [CI] =0.93–1.51 and OS: HR =1.12, P<0.001, 95% CI =0.85–1.40).

Conclusion

The ERCC1 rs11615 polymorphism was closely associated with the clinical outcomes of GC and CRC patients treated with oxaliplatin-based chemotherapy.

Technical reproducibility of single-nucleotide and size-based DNA biomarker assessment using DNA extracted from formalin-fixed, paraffin-embedded tissues

DNA extracted from formalin-fixed, paraffin-embedded (FFPE) tissues has been used in the past to analyze genetic polymorphisms. We evaluated the technical reproducibility of different types of assays for gene polymorphisms using DNA extracted from FFPE material. By using the MassARRAY iPLEX system, we investigated polymorphisms in DPYD (rs1801159 and rs3918290), UMPS (rs1801019), ERCC1 (rs11615), ERCC1 (rs3212986), and ERCC2 (rs13181) in 56 FFPE DNA samples. By using PCR, followed by size-based gel electrophoresis, we also examined TYMS 5' untranslated region 2R/3R repeats and GSTT1 deletions in 50 FFPE DNA samples and 34 DNAs extracted from fresh-frozen tissues and cell lines. Each polymorphism was analyzed by two independent runs. We found that iPLEX biomarker assays measuring single-nucleotide polymorphisms provided consistent concordant results. However, by using FFPE DNA, size-based PCR biomarkers (GSTT1 and TYMS 5' untranslated region) were discrepant in 32.7% (16/49, with exact 95% CI, 19.9%-47.5%; exact binomial confidence limit test) and 4.2% (2/48, with exact 95% CI, 0.5%-14.3%) of cases, respectively, whereas no discrepancies were observed using intact genomic DNA. Our findings suggest that DNA from FFPE material can be used to reliably test single-nucleotide polymorphisms. However, results based on size-based PCR biomarkers, and particularly GSTT1 deletions, using FFPE DNA need to be interpreted with caution. Independent repeated assays should be performed on all cases to assess potential discrepancies.

Recent studies of 5-fluorouracil resistance in pancreatic cancer

Resistance to 5-fluorouracil (5-FU), an important anticancer drug, is a serious challenge in the treatment of pancreatic cancer. Equilibrative nucleoside transporter 1 and multidrug-resistance protein (MRP) 5 and MRP8, rather than P-glycoprotein, play important roles in 5-FU transport. Thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase and thymidine phosphorylase are four key enzymes involved in 5-FU metabolism. Other metabolic enzymes, including uridine monophosphate synthetase, also contribute to chemoresistance. Intracellular signaling pathways are an integrated network, and nuclear factor kappa-light-chain-enhancer of activated B cells, AKT and extracellular signal-regulated kinases are signaling pathways that are particularly relevant to 5-FU resistance. In addition, recent reports indicate that STAT-3 is a crucial survival protein. Proteomic assays provide a powerful tool for identifying target proteins and understanding the role of microRNAs and stromal factors to facilitate the development of strategies to combat 5-FU resistance.

LRP5 polymorphism-A potential predictor of the clinical outcome in advanced gastric cancer patients treated with EOF regimen

PURPOSE

Wnt pathways control key biological processes that potentially impact on tumor progression and patient survival. The present study analyzed the polymorphism of lipoprotein-related receptor 5 (LRP5) (gene with key functions in Wnt signaling) and its impact on the response to chemotherapy and survival of patients with advanced gastric cancer (AGC).

METHODS

A total of 107 consecutive patients with AGC treated with first-line chemotherapy of EOF regimen were enrolled in the present retrospective study. The association between single nucleotide polymorphism (SNP) of rs3736228 in LRP5 and the clinical outcomes of the patients was studied.

RESULTS

The CC genotype of rs3736228 was significantly correlated with a higher disease control rate when compared to the CT and TT genotypes (89.3% and 61.8%, respectively, P<0.001). A univariate survival analysis also showed that the progression free survival (PFS) and overall survival (OS) for the patients with the TC and TT genotypes of rs3736228 were worse than for the patients with the CC genotype (PFS: 3.3 and 6.7 months, respectively, HR =0.454, P<0.001; OS: 8.1 months and 18.8 months, respectively, HR =3.056, P<0.001). A multivariate Cox model incorporates rs3736228 and clinical features, also identified rs3736228 was significantly associated with the PFS and OS.

CONCLUSIONS

Our results firstly highlight the importance of LRP5 gene of Wnt pathway in the treatment of AGC and identify polymorphism of rs3736228 as independent predictor of disease control rate, PFS and OS in AGC patients treated with first-line chemotherapy of EOF regimen in the Chinese Han population.

Association of DNA repair gene polymorphisms with response to chemotherapy and prognosis of gastric cancer in a Chinese population

We conducted a study to investigate the role of excision repair cross-complimentary group 1 gene (ERCC1)-xeroderma pigmentosum complementation group F (XPF) gene polymorphisms in response to chemotherapy and clinical outcome of gastric patients. Three SNPs in ERCC1 (rs11615, rs3212986, and rs2298881) and two SNPs in XPF (rs2276465 and rs6498486) were extracted using Tiangen DNA kit (Tiangen Biotech, Beijing, China) according to the manufacturer's instructions. The median follow-up time was 36.4 months, and ranged from 2-60 months. During the follow-up period, 112 patients died from gastric cancer. Individuals carrying ERCC1 rs11615 AA and XPF rs6498486 CC genotypes were associated with poorer response to chemotherapy when compared with wild-type genotype, with the ORs (95 % CI) of 0.48 (0.25-0.94) and 0.38 (0.14-1.00). In the Cox proportional hazards model, individuals carrying ERCC1 rs11615 GA and AA genotype had 1.91 and 2.66 risk of death when compared with those carrying GG genotype. Patients carrying the XPF rs6498486 AC and CC genotype were associate with 2.17 and 4.91-fold risk of death when compared with wild-type genotype. In conclusion, we found that ERCC1 rs11615 and XPF rs2276465 may substantially contribute to the future design of individualized cancer treatment in gastric cancer patients.

A retrospective comparative exploratory study on two methylentetrahydrofolate reductase (MTHFR) polymorphisms in esophagogastric cancer: the A1298C MTHFR polymorphism is an independent prognostic factor only in neoadjuvantly treated gastric cancer patients

Background

Methylentetrahydrofolate reductase (MTHFR) plays a major role in folate metabolism and consequently could be an important factor for the efficacy of a treatment with 5-fluorouracil. Our aim was to evaluate the prognostic and predictive value of two well characterized constitutional MTHFR gene polymorphisms for primarily resected and neoadjuvantly treated esophagogastric adenocarcinomas.

Methods

569 patients from two centers were analyzed (gastric cancer: 218, carcinoma of the esophagogastric junction (AEG II, III): 208 and esophagus (AEG I): 143). 369 patients received neoadjuvant chemotherapy followed by surgery, 200 patients were resected without preoperative treatment. The MTHFR C677T and A1298C polymorphisms were determined in DNA from peripheral blood lymphozytes. Associations with prognosis, response and clinicopathological factors were analyzed retrospectively within a prospective database (chi-square, log-rank, cox regression).

Results

Only the MTHFR A1298C polymorphisms had prognostic relevance in neoadjuvantly treated patients but it was not a predictor for response to neoadjuvant chemotherapy. The AC genotype of the MTHFR A1298C polymorphisms was significantly associated with worse outcome (p = 0.02, HR 1.47 (1.06-2.04). If neoadjuvantly treated patients were analyzed based on their tumor localization, the AC genotype of the MTHFR A1298C polymorphisms was a significant negative prognostic factor in patients with gastric cancer according to UICC 6^th edition (gastric cancer including AEG type II, III: HR 2.0, 95% CI 1.3-2.0, p = 0.001) and 7^th edition (gastric cancer without AEG II, III: HR 2.8, 95% CI 1.5-5.7, p = 0.003), not for AEG I. For both definitions of gastric cancer the AC genotype was confirmed as an independent negative prognostic factor in cox regression analysis. In primarily resected patients neither the MTHFR A1298C nor the MTHFR C677T polymorphisms had prognostic impact.

Conclusions

The MTHFR A1298C polymorphisms was an independent prognostic factor in patients with neoadjuvantly treated gastric adenocarcinomas (according to both UICC 6^th or 7^th definitions for gastric cancer) but not in AEG I nor in primarily resected patients, which confirms the impact of this enzyme on chemotherapy associated outcome.

Influence of ERCC1 and ERCC4 polymorphisms on response to prognosis in gastric cancer treated with FOLFOX-based chemotherapy

Polymorphisms in the excision repair cross-complimentary group 1 (ERCC1)-excision repair cross-complimentary group 4 (ERCC4) genes have been implicated in the prognosis of various cancers. We conducted a cohort study to investigate the role of ERCC1-ERCC4 gene polymorphisms on the response to chemotherapy and the role of these two gene polymorphisms on the clinical outcomes of gastric cancer. Four hundred forty-seven patients with newly diagnosed and histopathologically confirmed primary gastric cancer were collected in our study and were followed up until March 2012. ERCC1 (rs11615, rs3212986C>A, and rs2298881) and ERCC4 (rs226466C>G, rs2276465, and rs6498486) were selected and genotyped. The overall chemotherapy response rate for treatment was 68 %. Carriers of the rs11615 TT and T allele and ERCC1 rs2298881 CC and C allele had a marginally significantly higher response rate to the chemotherapy. In the Cox proportional hazard model, the hazard ratios (HRs) for overall survival (OS) in patients carrying ERCC1 rs11615 TT genotype and T allele were 0.53 (0.29-0.95) and 0.63 (0.42-0.94), respectively. Similarly, we found a significant decreased risk of death from gastric cancer among patients carrying ERCC1 rs2298881 CC genotype and C allele when compared with CC genotype, and HRs (95% confidence interval (CI)) of OS were 0.50 (0.24-0.98) and 0.62 (0.40-0.96), respectively. Moreover, individuals carrying ERCC1 rs11615 T allele and rs2298881 C allele could decrease a 0.62-fold risk of death from gastric cancer. This study reported a carriage of ERCC1 rs11615, and rs2298881 polymorphism can be used as a predictor of response to folinic acid/5-fluorouracil (5-FU)/oxaliplatin (FOLFOX)-based chemotherapy in gastric cancer patients.

ERCC1 and ERCC2 variants predict survival in gastric cancer patients

Purpose

ERCC1 and ERCC2 play critical roles in the nucleotide excision repair pathway that effectively repairs DNA damage induced by chemotherapeutic agents. Therefore, functional single nucleotide polymorphisms (SNPs) in these genes could have an impact on clinical outcomes in cancer patients who received chemotherapy. However, few studies have simultaneously investigated the roles of ERCC1 and ERCC2 SNPs in clinical outcomes in gastric cancer patients.

Experimental Design

We genotyped by the TaqMan assay three common, potentially functional ERCC1 (rs3212986) and ERCC2 SNPs (rs13181 and rs1799793) in 360 gastric cancer patients. We used both Kaplan-Meier tests and Cox proportional hazards models to evaluate the effects of ERCC1 and ERCC2 genotypes and haplotypes on clinical outcomes.

Results

We found that, compared with ERCC2 rs1799793 GG+AG genotypes, the homozygous variant AA genotype was associated with significantly poorer overall survival (OS) (AA vs. GG+AG, log-rank P = 0.012) and significantly higher risk of death (AA vs. GG+AG, Adjusted hazards ratio [HR] 2.13; 95% CI, 1.28 to 3.56; P = 0.004). In combined analyses, patients with any one of the three unfavorable genotypes (i.e. ERCC1 rs3212986 TT, ERCC2 rs13181 GG and rs1799793 AA) had statistically significant hazards of poor prognosis (Adjusted HR, 1.54; 95% CI, 1.06 to 2.25; P = 0.025), compared with those without any unfavorable genotypes. Furthermore, the haplotype A-G-G (rs1799793/rs13181/rs3212986) had a significant impact on OS (Adjusted HR, 1.57; 95% CI, 1.11 to 2.21; P = 0.011), compared with the common haplotype G-T-G.

Conclusion

ERCC1 and ERCC2 functional SNPs may jointly affect OS in Caucasian gastric cancer patients. Additional large prospective studies are essential to confirm our findings.

Tumor site- and stage-specific associations between allelic variants of glutathione S-transferase and DNA-repair genes and overall survival in colorectal cancer patients receiving 5-fluorouracil-based chemotherapy

Introduction

Our retrospective cohort study investigated the effect of tumor site and stage on the associations between the allelic variants of glutathione S-transferase (GST) and DNA-repair genes and overall survival (OS) in CRC patients treated with 5-fluorouracil (5-FU)-based adjuvant chemotherapy.

Material and Methods

We genotyped GSTM1, GSTT1, GSTP1 Ile105Val, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln in 491 CRC patients between 1995 and 2001. A Cox proportional-hazards model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the relationships between the allelic variants and OS. Survival analyses were performed for each allelic variant by using the log-rank test and Kaplan-Meier analysis.

Results

The CRC patients with the XPD Gln allelic variants had poorer survival than patients with the Lys/Lys genotype (HR  = 1.38, 95% CI  = 1.02–1.87), and rectal cancer patients had the poorest survival among them (HR  = 1.87, 95% CI  = 1.18–2.95). A significantly shorter OS was observed among stage II/III colon cancer patients with the XRCC1 Gln allelic variants (HR  = 1.69, 95% CI  = 1.06–2.71), compared to those with XRCC1 Arg/Arg genotype. In the combined analysis of the XRCC1 and XPD genes patients with stage II/III tumors, the poorest OS occurred in colon cancer patients with the XRCC1 Gln and XPD Gln allelic variants (HR  = 2.60, 95% CI  = 1.19–5.71) and rectal cancer patients with the XRCC1 Arg/Arg and XPD Gln allelic variants (HR  = 2.77, 95% CI  = 1.25–6.17).

Conclusion

The XPD and XRCC1 allelic variants may be prognostic markers for CRC patients receiving 5-FU based chemotherapy. The contributions of the XPD and XRCC1 allelic variants to OS are tumor site- and/or stage-dependent.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

A genetic variant in ERCC2 is associated with gastric cancer prognosis in a Chinese population

Endogenous and exogenous factors can induce DNA damage, leading to increased risk of cancer. Nucleotide excision repair (NER) is considered as the most versatile DNA repair pathway to deal with a variety of different DNA lesions. ERCC1 and ERCC2 are the two important proteins in NER pathway. In this study, we investigated the association of three functional single nucleotide polymorphisms (SNPs) (ERCC1 rs11615, ERCC2 rs13181 and ERCC2 rs1799793) with the clinical outcome of 940 gastric cancer patients in a Chinese population. Multiplex SNaPshot technology was used to genotype these three SNPs. Our results revealed that individuals with ERCC2 rs13181TG/GG genotypes had a decreased risk of death compared with those with TT genotype [log-rank P = 0.008; adjusted hazard ratio = 0.68, 95% confidence interval = 0.51-0.91] and this protective effect was more pronounced among the subgroups of patients with tumour size ≤ 5 cm (0.59, 0.39-0.89), non-cardia gastric tumour (0.69, 0.48-0.98), no lymph node metastasis (0.55, 0.32-0.96), no distant metastasis (0.70, 0.52-0.95) and chemotherapy (0.39, 0.21-0.72). We conclude that ERCC2 rs13181 polymorphism could play different roles in the overall survival of gastric cancer. Further larger studies should be conducted to validate our findings.

ERCC1 predicts outcome in patients with gastric cancer treated with adjuvant cisplatin-based chemotherapy

BACKGROUND

Adjuvant chemotherapy is gaining an increasing role in resectable gastric cancer. Customizing chemotherapy on the basis of chemosensitivity may improve outcome, and putative predictive molecular markers have been mostly evaluated in Asian patients. We profiled key DNA and damage signaling factors and correlated them with outcome, in a European cohort.

METHODS

Formalin-fixed tumor samples obtained from surgical specimens of patients treated with adjuvant cisplatin-based chemotherapy for gastric cancer were analyzed. Immunohistochemistry (IHC) was performed to analyze excision repair cross-complementing gene 1 (ERCC1) and thymidylate synthase (TS) expression, and p53 mutations were detected with direct sequencing.

RESULTS

Among the 68 patient recruited, the median age was 69 (range 30-74), and UICC stage was III in 44 patients (65 %). With a median follow-up of 40.5 months, disease-free and overall survival were 18.0 (95 % CI 13.4-22.76) and 56 months (95 % CI 44.87-67.13), respectively. ERCC1 score was 0 in 14 out 67 (21 %) cases, 1 in 19 (28 %), 2 in 20 (30 %) and 3 in 14 cases (21 %). Longer overall survival (p = 0.04) was found in patients categorized as ERCC1 negative by IHC according to median score. TS score was 0 in 16 out 67 (24 %) cases, 1 in 27 (40 %), 2 in 16 (24 %) and 3 in 8 cases (12 %). Mutations of p53 were found in 21 out 66 (32 %) cases. Neither TS nor p53 were found to correlate with outcome.

CONCLUSION

Excision repair cross-complementing gene 1 by IHC might predict patients more likely to benefit from adjuvant cisplatin-based chemotherapy in curatively resected gastric cancer. In patients exhibiting ERCC1 positive tumors, alternative regimens should be evaluated.