Dose-response association between cigarette smoking and gastric cancer risk: a systematic review and meta-analysis

This study aims at providing an accurate and up-to-date quantification of the dose-response association between cigarette smoking and gastric cancer (GC) risk, overall and by subsite. We conducted a systematic review and meta-analysis of case-control and cohort studies on the association between cigarette smoking and GC risk published up to January 2023. We estimated pooled relative risks (RR) of GC and its subsites according to smoking status, intensity, duration, and time since quitting. Among 271 eligible articles, 205 original studies were included in this meta-analysis. Compared with never smokers, the pooled RR for GC was 1.53 (95% confidence interval; CI 1.44-1.62; n = 92) for current and 1.30 (95% CI 1.23-1.37; n = 82) for former smokers. The RR for current compared with never smokers was 2.08 (95% CI 1.66-2.61; n = 21) for gastric cardia and 1.48 (95% CI 1.33-1.66; n = 8) for distal stomach cancer. GC risk nonlinearly increased with smoking intensity up to 20 cigarettes/day (RR:1.69; 95% CI 1.55-1.84) and levelled thereafter. GC risk significantly increased linearly with increasing smoking duration (RR: 1.31; 95% CI 1.25-1.37 for 20 years) and significantly decreased linearly with increasing time since quitting (RR: 0.65; 95% CI 0.44-0.95 for 30 years since cessation). The present meta-analysis confirms that cigarette smoking is an independent risk factor for GC, particularly for gastric cardia. GC risk increases with a low number of cigarettes up to 20 cigarettes/day and increases in a dose-dependent manner with smoking duration.

Clinicopathologic differences of gastric neoplasms between Helicobacter pylori-infected and -naïve patients: a multicenter retrospective analysis

BACKGROUND

The incidence of gastric neoplasms in Helicobacter pylori (Hp)-naïve patients has recently increased due to a remarkable decrease in the Hp-infected population in Japan. We investigated the clinicopathologic differences between Hp-infected gastric neoplasms (HpIGNs) and Hp-naïve gastric neoplasms (HpNGNs) that have not been fully elucidated so far.

METHODS

This retrospective multicenter study investigated 966 consecutive patients with 1131 gastric dysplasia or cancers who underwent endoscopic or surgical treatment for the recent decade. Clinicopathologic features were compared between HpIGN and HpNGN cases.

RESULTS

One thousand and sixty-eight HpIGNs in 916 patients included 877 differentiated types and 191 undifferentiated types. Sixty-three HpNGNs in 50 patients included 57 differentiated types (35 foveolar types, 15 intestinal types, 6 fundic-gland types, and 1 other differentiated type) and 6 undifferentiated types. HpNGNs occurred in younger (59.5 vs. 71.8 years, p < 0.05) and female patients (40.0% vs. 26.5%, p < 0.05), were found more frequently in the proximal compartment (p < 0.05), and had smaller size (median 4.0 vs. 20.0 mm, p < 0.05). Histologically, HpNGNs and HpIGNs both primarily consisted of differentiated type (90.5% vs. 82.1%, p = 0.089) and HpNGNs showed lower prevalence of invasive cancer (11.1% vs. 37.6%, p < 0.05) and lymphovascular invasion (1.6% vs. 31.6%, p < 0.05). Nearly all HpNGNs (62/63, 98.4%) were diagnosed in early pathological stage, while 16.1% (172/1068) of HpIGNs were diagnosed in advanced stage (p < 0.05).

CONCLUSIONS

HpNGNs is recently on the increase but shows lower malignant nature regardless of histologic type than HpIGN. Endoscopic gastric cancer screening will be reviewed via cost effectiveness for Hp-naïve individuals in future.

Systematic replication of smoking disease associations using survey responses and EHR data in the All of Us Research Program

OBJECTIVE

The All of Us Research Program (All of Us) aims to recruit over a million participants to further precision medicine. Essential to the verification of biobanks is a replication of known associations to establish validity. Here, we evaluated how well All of Us data replicated known cigarette smoking associations.

MATERIALS AND METHODS

We defined smoking exposure as follows: (1) an EHR Smoking exposure that used International Classification of Disease codes; (2) participant provided information (PPI) Ever Smoking; and, (3) PPI Current Smoking, both from the lifestyle survey. We performed a phenome-wide association study (PheWAS) for each smoking exposure measurement type. For each, we compared the effect sizes derived from the PheWAS to published meta-analyses that studied cigarette smoking from PubMed. We defined two levels of replication of meta-analyses: (1) nominally replicated: which required agreement of direction of effect size, and (2) fully replicated: which required overlap of confidence intervals.

RESULTS

PheWASes with EHR Smoking, PPI Ever Smoking, and PPI Current Smoking revealed 736, 492, and 639 phenome-wide significant associations, respectively. We identified 165 meta-analyses representing 99 distinct phenotypes that could be matched to EHR phenotypes. At P < .05, 74 were nominally replicated and 55 were fully replicated. At P < 2.68 × 10-5 (Bonferroni threshold), 58 were nominally replicated and 40 were fully replicated.

DISCUSSION

Most phenotypes found in published meta-analyses associated with smoking were nominally replicated in All of Us. Both survey and EHR definitions for smoking produced similar results.

CONCLUSION

This study demonstrated the feasibility of studying common exposures using All of Us data.

Case-control study on CYP4B1 gene polymorphism and susceptibility to gastric cancer in the chinese Han population

Background:

In China, gastric cancer (GC) is one of the most common malignant tumors. This study aimed to explore the relationship of rs2297810, rs4646491 and rs2297809 polymorphisms of CYP4B1 with susceptibility to GC in the Chinese Han population.

Methods:

A case-control study including 707 GC cases and 707 normal controls was conducted. Three single nucleotide polymorphisms (SNPs) were genotyped by Agena MassARRAY system. Logistic regression analysis was utilized to assess the effects of SNPs on GC risk. Furthermore, multifactor dimensionality reduction (MDR) approach was used to analyze the SNP-SNP interactions.

Results:

No significant relationships were found between rs2297810 and rs2297809 and GC risk under all genetic models. For rs4646491, people with TC genotype had a 1.40-fold higher risk of GC than those with CC genotype (OR = 1.40; 95% CI = 1.13–1.74; p = 0.002), and people with TT-TC genotype had a 1.30-fold higher risk of GC than those with CC genotype (OR = 1.30; 95% CI = 1.06–1.61; p = 0.014). Stratification results showed that GC risk in people carrying TC genotype was higher than that in people with CC genotype, males (OR = 1.36; 95% CI = 1.06–1.75; p = 0.015), non-smokers (OR = 1.52; 95% CI = 1.11–2.07; p = 0.009) and non-drinkers (OR = 1.50; 95% CI = 1.10–2.04; p = 0.010). Additionally, the study also revealed that GC risk in people carrying TT-TC genotype was higher than that in people with CC genotype, males (OR = 1.29; 95% CI = 1.01–1.64; p = 0.040), non-smokers (OR = 1.40; 95% CI = 1.04–1.89; p = 0.027) and non-drinkers (OR = 1.39; 95% CI = 1.03–1.87; p = 0.030).

Conclusion:

This study firstly found that CYP4B1-rs4646491 was significantly correlated with GC risk, and it might be a risk factor for GC.

Dietary Salt Intake and Gastric Cancer Risk: A Systematic Review and Meta-Analysis

The results of prospective cohort studies regarding the role of salt intake and subsequent gastric cancer risk are inconsistent. Thus, we performed a systematic review and meta-analysis to summarize the strength of the association of salt intake with gastric cancer morbidity and mortality. PubMed, EmBase, and Cochrane Library were systematically searched to identify eligible studies published throughout September 2021. The effect estimates with 95% confidence intervals (CIs) for gastric cancer morbidity or mortality in each study were applied to calculate the pooled results; these analyses were performed using the random-effects model. Twenty-six prospective cohort studies involving 4,956,350 individuals were selected; these studies reported 19,301 cases of gastric cancer and 2,871 cases of gastric cancer-associated mortality. High (RR: 1.25; 95%CI: 1.10–1.41; P = 0.001) or moderate (RR: 1.20; 95%CI: 1.04–1.38; P = 0.012) salt intake was associated with a greater risk of gastric cancer. High pickled food intake was associated with an increased gastric cancer risk (RR: 1.28; 95%CI: 1.05–1.57; P = 0.017), while moderate pickled foods intake had no significant effect on gastric cancer risk (RR: 1.10; 95%CI: 0.88–1.37; P = 0.390). Neither high (RR: 1.14; 95%CI: 0.95–1.36; P = 0.161) nor moderate (RR: 1.10; 95%CI: 0.87–1.40; P = 0.436) salted fish intake were associated with gastric cancer risk. A high intake of processed meat was significantly associated with a higher risk of gastric cancer (RR: 1.24; 95%CI: 1.03–1.49; P = 0.023), while moderate processed meat intake had no significant effect on the gastric cancer risk (RR: 1.01; 95%CI: 0.92–1.11; P = 0.844). High (RR: 1.04; 95%CI: 0.90–1.19; P = 0.626) and moderate (RR: 1.02; 95%CI: 0.94–1.11; P = 0.594) miso-soup intake had no effects on the gastric cancer risk. High intakes of salt, pickled food, and processed meat are associated with significantly increased risks of gastric cancer; these increased risks are also seen when participants consumed moderate amounts of salt.

Ornithine decarboxylase (ODC1) gene variant (rs2302615) is associated with gastric cancer independently of Helicobacter pylori CagA serostatus

The primary cause of gastric cancer is chronic infection with Helicobacter pylori (H. pylori), particularly the high-risk genotype cagA, and risk modification by human genetic variants. We studied 94 variants in 54 genes for association with gastric cancer, including rs2302615 in ornithine decarboxylase (ODC1), which may affect response to chemoprevention with the ODC inhibitor, eflornithine (difluoromethylornithine; DFMO). Our population-based, case-control study included 1366 individuals (664 gastric cancer cases and 702 controls) from Western Honduras, a high incidence region of Latin America. CagA seropositivity was strongly associated with cancer (OR = 3.6; 95% CI: 2.6, 5.1). The ODC1 variant rs2302615 was associated with gastric cancer (OR = 1.36; p = 0.018) in a model adjusted for age, sex, and CagA serostatus. Two additional single nucleotide polymorphisms (SNPs) in CASP1 (rs530537) and TLR4 (rs1927914) genes were also associated with gastric cancer in univariate models as well as models adjusted for age, sex, and CagA serostatus. The ODC1 SNP association with gastric cancer was stronger in individuals who carried the TT genotype at the associating TLR4 polymorphism, rs1927914 (OR = 1.77; p = 1.85 × 10^-3). In conclusion, the ODC1 variant, rs2302615, is associated with gastric cancer and supports chemoprevention trials with DFMO, particularly in individuals homozygous for the T allele at rs1927914.

Helicobacter pylori-Induced Inflammation: Possible Factors Modulating the Risk of Gastric Cancer

Chronic inflammation and long-term tissue injury are related to many malignancies, including gastric cancer (GC). Helicobacter pylori (H. pylori), classified as a class I carcinogen, induces chronic superficial gastritis followed by gastric carcinogenesis. Despite a high prevalence of H. pylori infection, only about 1–3% of people infected with this bacterium develop GC worldwide. Furthermore, the development of chronic gastritis in some, but not all, H. pylori-infected subjects remains unexplained. These conflicting findings indicate that clinical outcomes of aggressive inflammation (atrophic gastritis) to gastric carcinogenesis are influenced by several other factors (in addition to H. pylori infection), such as gut microbiota, co-existence of intestinal helminths, dietary habits, and host genetic factors. This review has five goals: (1) to assess our current understanding of the process of H. pylori-triggered inflammation and gastric precursor lesions; (2) to present a hypothesis on risk modulation by the gut microbiota and infestation with intestinal helminths; (3) to identify the dietary behavior of the people at risk of GC; (4) to check the inflammation-related genetic polymorphisms and role of exosomes together with other factors as initiators of precancerous lesions and gastric carcinoma; and (5) finally, to conclude and suggest a new direction for future research.

Risk factors for gastric cancer: a large-scale, population-based case-control study

Background:

Early detection of gastric cancer (GC) has been the topic of major efforts in China. This study aimed to explore the risk factors associated with GC and to provide evidence for the selection of a high-risk population of GC.

Methods:

Based on the cancer screening cohort of the National Cancer Screening Program in Urban China, GC patients diagnosed by endoscopy and pathological examinations constituted the case group, and controls were 1:3 matched by sex and age (±5 years) individually. The variables were selected by univariable analysis of factors such as body mass index (BMI), dietary habits, lifestyle, stomach disease history, and family history of GC; and multivariable logistic regression was used to analyze the influencing factors of GC and to calculate the odds ratio (OR) of related factors and its 95% confidence interval (CI).

Results:

A total of 215 GC cases and 645 matched healthy controls were included in the final analysis, with a median age of 61 years for the case and control groups. Overall analysis showed that high educational level (above primary school) (OR = 0.362, 95% CI = 0.219–0.599, P < 0.001), overweight/obesity (BMI ≥24 kg/m²; OR = 0.489, 95% CI = 0.329–0.726, P < 0.001), cigarette smoking (OR = 3.069, 95% CI = 1.700–5.540, P < 0.001), alcohol consumption (OR = 1.661, 95% CI = 1.028–2.683, P = 0.038), history of stomach disease (OR = 6.917, 95% CI = 4.594–10.416, P < 0.001), and family history of GC in first-degree relatives (OR = 4.291, 95% CI = 1.661–11.084, P = 0.003) were significantly correlated with the occurrence of GC. Subgroup analyses by age and gender indicated that GC risk was still increased in the presence of a history of stomach disease. A history of chronic gastritis, gastric ulcer, or gastric polyposis was positively associated with GC, with adjusted ORs of 4.155 (95% CI = 2.711–6.368), 1.839 (95% CI = 1.028–3.288), and 2.752 (95% CI = 1.197–6.326).

Conclusions:

Subjects who smoke, drink, with history of stomach disease and family history of GC in first-degree relatives are the high-risk populations for GC. Therefore, attention should be paid to these subjects for GC screening.

A comprehensive update on early gastric cancer: defining terms, etiology, and alarming risk factors

INTRODUCTION

Early gastric cancer (EGC) is a well-defined gastric malignancy that is limited to the mucosa or submucosa, irrespective of lymph node metastasis. At an early stage, gastric cancer often does not cause symptoms until it becomes advanced, and it is a heterogeneous disease and usually encountered in its late stages.

AREA COVERED

This comprehensive review will provide a novel insight into the evaluation of EGC epidemiology, defining terms, extensive etiology and risk factors, and timely diagnosis since prevention is an essential approach for controlling this cancer and reducing its morbidity and mortality.

EXPERT OPINION

The causative manner of EGC is complex and multifactorial. In recent years, researchers have made significant contributions to understanding the etiology and pathogenesis of EGC, and standardization in the evaluation of disease activity. Though the incidence of this cancer is steadily declining in some advanced societies owing to appropriate interventions, there remains a serious threat to health in developing nations. Early detection of resectable gastric cancer is crucial for better patient outcomes.

Prediction of gastric cancer risk: association between ZBTB20 genetic variance and gastric cancer risk in Chinese Han population

Background: Gastric cancer (GC) is a complex multifactorial disease. Previous studies have revealed genetic variations associated with the risk of gastric cancer. The purpose of the present study was to determine the correlation between single-nucleotide polymorphisms (SNPs) of ZBTB20 and the risk of gastric cancer in Chinese Han population.

Methods: We conducted a ‘case–control’ study involving 509 GC patients and 507 healthy individuals. We selected four SNPs of ZBTB20 (10934270 T/C, rs9288999 G/A, rs9841504 G/C and rs73230612 C/T), and used logistic regression to analyze the relationship between those SNPs and GC risk under different genetic models; multi-factor dimensionality reduction (MDR) was used to analyze the interaction of “SNP–SNP” in gastric cancer risk; ANOVA and univariate analysis were used to analyze the differences in clinical characteristics among different genotypes.

Results: Our results showed that ZBTB20 rs9288999 is a protective factor for the risk of gastric cancer in multiple genetic models, of which the homozygous model is the most significant (OR = 0.48, P=0.0003); we also found that rs9288999 showed a significant correlation with reducing the risk of gastric cancer in different subgroups (BMI; age; gender; smoking or drinking status; adenocarcinoma); rs9841504 is associated with increased GC risk in the participants with BMI>24 kg/m²; rs9841504 and rs73230612 are certainly associated with clinical characteristics of platelet and carbohydrate antigen 242, respectively.

Conclusion: Our results suggest that ZBTB20 rs9288999 may be important for reducing the risk of GC in the Chinese Han population.

Helicobacter pylori Infection, Virulence Genes' Distribution and Accompanying Clinical Outcomes: The West Africa Situation

Data on Helicobacter pylori (H. pylori) infection and virulence factors in countries across West Africa are scattered. This systematic review seeks to present an update on the status of H. pylori infection focusing on prevalence rate, distribution of virulent genes, and their link to clinical outcomes across countries in the western part of Africa. This information is expected to broaden the knowledge base of clinicians and researchers regarding H. pylori infection and associated virulence factors in West African countries. Search Method. A comprehensive search of the scientific literature in PubMed and ScienceDirect was conducted using the search terms including “Helicobacter pylori infection in West Africa”. Databases were sourced from January 1988 to December 2018. Results. Data on the incidence of H. pylori infection and related pathological factors were found for some countries, whereas others had no information on it. Smoking, alcohol, exposure to high levels of carcinogens and diet were reported to be involved in the pathogenesis of gastroduodenal diseases and gastric cancer. Besides the environmental factors and genetic characteristics, there are important characteristics of H. pylori such as the ability to infect, replicate, and persist in a host that have been associated with the pathogenesis of various gastroduodenal diseases. Concluding Remarks. This systematic search has provided information so far available on H. pylori virulence factors and clinical outcomes in West Africa. Accordingly, this piece has identified gaps in the body of knowledge highlighting the need for more studies to clarify the role of H. pylori virulence factors and associated clinical outcomes in the burden of this bacterial infection in West Africa, as data from these countries do not give the needed direct relation.

Development and validation of a prediction rule for estimating gastric cancer risk in the Chinese high-risk population: a nationwide multicentre study

OBJECTIVE

To develop a gastric cancer (GC) risk prediction rule as an initial prescreening tool to identify individuals with a high risk prior to gastroscopy.

DESIGN

This was a nationwide multicentre cross-sectional study. Individuals aged 40-80 years who went to hospitals for a GC screening gastroscopy were recruited. Serum pepsinogen (PG) I, PG II, gastrin-17 (G-17) and anti-Helicobacter pylori IgG antibody concentrations were tested prior to endoscopy. Eligible participants (n=14 929) were randomly assigned into the derivation and validation cohorts, with a ratio of 2:1. Risk factors for GC were identified by univariate and multivariate analyses and an optimal prediction rule was then settled.

RESULTS

The novel GC risk prediction rule comprised seven variables (age, sex, PG I/II ratio, G-17 level, H. pylori infection, pickled food and fried food), with scores ranging from 0 to 25. The observed prevalence rates of GC in the derivation cohort at low-risk (≤11), medium-risk (12-16) or high-risk (17-25) group were 1.2%, 4.4% and 12.3%, respectively (p<0.001).When gastroscopy was used for individuals with medium risk and high risk, 70.8% of total GC cases and 70.3% of early GC cases were detected. While endoscopy requirements could be reduced by 66.7% according to the low-risk proportion. The prediction rule owns a good discrimination, with an area under curve of 0.76, or calibration (p<0.001).

CONCLUSIONS

The developed and validated prediction rule showed good performance on identifying individuals at a higher risk in a Chinese high-risk population. Future studies are needed to validate its efficacy in a larger population.

Tobacco smoking and gastric cancer: meta-analyses of published data versus pooled analyses of individual participant data (StoP Project)

Tobacco smoking is one of the main risk factors for gastric cancer, but the magnitude of the association estimated by conventional systematic reviews and meta-analyses might be inaccurate, due to heterogeneous reporting of data and publication bias. We aimed to quantify the combined impact of publication-related biases, and heterogeneity in data analysis or presentation, in the summary estimates obtained from conventional meta-analyses. We compared results from individual participant data pooled-analyses, including the studies in the Stomach Cancer Pooling (StoP) Project, with conventional meta-analyses carried out using only data available in previously published reports from the same studies. From the 23 studies in the StoP Project, 20 had published reports with information on smoking and gastric cancer, but only six had specific data for gastric cardia cancer and seven had data on the daily number of cigarettes smoked. Compared to the results obtained with the StoP database, conventional meta-analyses overvalued the relation between ever smoking (summary odds ratios ranging from 7% higher for all studies to 22% higher for the risk of gastric cardia cancer) and yielded less precise summary estimates (SE ≤2.4 times higher). Additionally, funnel plot asymmetry and corresponding hypotheses tests were suggestive of publication bias. Conventional meta-analyses and individual participant data pooled-analyses reached similar conclusions on the direction of the association between smoking and gastric cancer. However, published data tended to overestimate the magnitude of the effects, possibly due to publication biases and limited the analyses by different levels of exposure or cancer subtypes.

Cigarette smoking and gastric cancer in the Stomach Cancer Pooling (StoP) Project

Tobacco smoking is a known cause of gastric cancer, but several aspects of the association remain imprecisely quantified. We examined the relation between cigarette smoking and the risk of gastric cancer using a uniquely large dataset of 23 epidemiological studies within the 'Stomach cancer Pooling (StoP) Project', including 10 290 cases and 26 145 controls. We estimated summary odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) by pooling study-specific ORs using random-effects models. Compared with never smokers, the ORs were 1.20 (95% CI: 1.09-1.32) for ever, 1.12 (95% CI: 0.99-1.27) for former, and 1.25 (95% CI: 1.11-1.40) for current cigarette smokers. Among current smokers, the risk increased with number of cigarettes per day to reach an OR of 1.32 (95% CI: 1.10-1.58) for smokers of more than 20 cigarettes per day. The risk increased with duration of smoking, to reach an OR of 1.33 (95% CI: 1.14-1.54) for more than 40 years of smoking and decreased with increasing time since stopping cigarette smoking (P for trend<0.01) and became similar to that of never smokers 10 years after stopping. Risks were somewhat higher for cardia than noncardia gastric cancer. Risks were similar when considering only studies with information on Helicobacter pylori infection and comparing all cases to H. pylori+ controls only. This study provides the most precise estimate of the detrimental effect of cigarette smoking on the risk of gastric cancer on the basis of individual data, including the relationship with dose and duration, and the decrease in risk following stopping smoking.

Tipping the Scale Toward Gastric Disease: A Host-Pathogen Genomic Mismatch?

PURPOSE OF REVIEW

Chronic infection with Helicobacter pylori infection is necessary but not sufficient to initiate development of intestinal-type gastric adenocarcinoma. It is not clear what additional factors tip the scale from commensal bacteria towards a pathogen that facilitates development of gastric cancer. Genetic variants in both the pathogen and host have been implicated, but neither alone explains a substantial portion of disease risk.

RECENT FINDINGS

In this review, we consider studies that address the important role of human and bacterial genetics, ancestry and their interactions in determining gastric disease risk. We observe gaps in the current literature that should guide future work to confirm the hypothesis of the interacting roles of host and bacterial genetics that will be necessary to translate these findings into clinically relevant information.

SUMMARY

We summarize genetic risk factors for gastric disease in both H. pylori and human hosts. However, genetic variation of one or the other organism in isolation insufficiently explains gastric disease risk. The most promising models of gastric disease risk simultaneously consider the genetic variation of both the H. pylori and human host, under a co-evolution model.

SNP interactions of PGC with its neighbor lncRNAs enhance the susceptibility to gastric cancer/atrophic gastritis and influence the expression of involved molecules

Multidimensional interactions of multiple factors are more important in promoting cancer initiation. Gene-gene interactions between protein-coding genes have been paid great attention, while rare studies refer to the interactions between encoding and noncoding genes. Our research group previously found encoding gene PGC polymorphisms could affect the susceptibility to atrophic gastritis (AG) and gastric cancer (GC). Interestingly, several SNPs in long noncoding RNA (lncRNA) genes, just adjacent to PGC, were found to be associated with AG risk and GC prognosis afterward. This study aims to explore the SNP interactions between PGC and its neighbor lncRNAs on the risk of AG and GC. Genotyping for seven PGC SNPs and seven lncRNA SNPs was conducted using Sequenom MassARRAY platform in a total of 2228 northern Chinese subjects, including 536 GC cases, 810 AG cases, and 882 controls. We found 15 pairwise PGC-lncRNAs SNPs had interactions: Five pairs were associated with AG risk, and ten pairs were associated with GC risk. Moreover, two GC-related interactions PGC rs6939861 with lnc-C6orf-132-1 rs7749023 and rs7747696 survived the Bonferroni correction (P_correction  = 0.049 and 0.007, respectively). Several combinations showed obvious epistasis and cumulative effects on disease risk. Some three-way interactions of SNPs with smoking and drinking could also be observed. Besides, a few interacting SNPs showed correlations with the expression levels of PGC protein and related lncRNAs in serum. Our study would provide research clues for further screening combination biomarkers uniting both protein-coding and noncoding genes with the potential in prediction of the susceptibility to GC and its precursor.

Acetylcholine induces stem cell properties of gastric cancer cells of diffuse type

Gastric cancer is the third leading cause of cancer-related death worldwide, but the mechanisms of gastric carcinogenesis are not completely understood. Recently, the role of cholinergic neuronal pathways in promoting this process has been demonstrated. Our aim was to extend these studies and to evaluate, using an in vitro model of tumorspheres, the effect of acetylcholine on human gastric cancer cells, and the role of acetylcholine receptors and of the nitric oxide pathway, in this effect. The gastric cancer cell line MKN-45 of the diffuse type of gastric cancer was cultured in the presence of acetylcholine, or different agonists or inhibitors of muscarinic and nicotinic acetylcholine receptors, or nitric oxide donor or inhibitor of the nitric oxide pathway, and the number and size of tumorspheres were assessed. The expression of cancer stem cell markers (CD44 and aldehyde dehydrogenase) was also evaluated by immunofluorescence and quantitative reverse transcription polymerase chain reaction. We showed that acetylcholine increased both the number and size of tumorspheres and that this effect was reproduced with both muscarinic and nicotinic acetylcholine receptors agonists and was inhibited by both receptor antagonists. The nitric oxide donor stimulated the tumorsphere formation, while the nitric oxide synthesis inhibitor inhibited the stimulatory effect of acetylcholine. Moreover, acetylcholine increased the expression of stem cell markers on gastric cancer cells. These results indicate that acetylcholine induces the stem cell properties of gastric cancer cells and both muscarinic and nicotinic receptors and a nitrergic pathway might be involved in this effect.

Can a gastric cancer risk survey identify high-risk patients for endoscopic screening? A pilot study

BACKGROUND

A questionnaire that distinguishes how variability in gastric cancer prevalence is associated with ethnicity/birth country/immigration/cultural diet along with known risk factors may improve targeting populations for gastric cancer screening in the United States.

METHODS

Existing literature was used to identify the item pool. Cluster analysis, focus groups, and cognitive interviewing were used to reduce collinear items and refine the questionnaire. Logistic regression analysis was used to determine which items distinguished gastric cancer cases from the primary care and community controls.

RESULTS

The results of analysis of data from 40 cases and 100 controls (primary care = 47; community = 53) were used to reduce the 227 item pool to 12 items. After ranking these variables using model bootstrapping, a logistic regression model using the highest ranked eight variables was chosen as the final model. Older age, foreign nativity, daily consumption of cultural food at ages 15-18, less than high-school education, and greater acculturation were significantly associated with being a gastric cancer case compared with the controls.

CONCLUSIONS

An eight-item survey that addresses gastric cancer risk factors, ethnicity, cultural habits, and immigration patterns has potential to identify high-risk persons from multicultural areas within the US, who might benefit from endoscopic screening for gastric cancer.

Helicobacter pylori-induced gastric pathology: insights from in vivo and ex vivo models

Gastric colonization with Helicobacter pylori induces diverse human pathological conditions, including superficial gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma and its precursors. The treatment of these conditions often relies on the eradication of H. pylori, an intervention that is increasingly difficult to achieve and that does not prevent disease progression in some contexts. There is, therefore, a pressing need to develop new experimental models of H. pylori-associated gastric pathology to support novel drug development in this field. Here, we review the current status of in vivo and ex vivo models of gastric H. pylori colonization, and of Helicobacter-induced gastric pathology, focusing on models of gastric pathology induced by H. pylori, Helicobacter felis and Helicobacter suis in rodents and large animals. We also discuss the more recent development of gastric organoid cultures from murine and human gastric tissue, as well as from human pluripotent stem cells, and the outcomes of H. pylori infection in these systems.

Family history of gastric cancer is associated with the risk of colorectal neoplasia in Korean population

BACKGROUND

Family history of cancers at different sites except for colorectum has not been evaluated as a risk factor for colorectal neoplasia (CRN).

AIMS

To investigate CRN risk according to family history of cancers at 12 different sites, including stomach and colorectum.

METHODS

A cross-sectional study was performed on 139,497 asymptomatic Koreans who underwent colonoscopy as part of a health check-up.

RESULTS

The mean age of the study population was 41.6 and the prevalence of CRN was 16.3%. Multivariate analyses revealed that family histories of CRC (adjusted odds ratio; confidence interval, 1.26; 1.17-1.35) and gastric cancer (1.07; 1.01-1.13) were independent risk factors for CRN. Notably, the risk of CRN increased even more for participants with family histories of both CRC and gastric cancer (1.38; 1.12-1.70). Family history of CRC was associated with risk of CRN in participants aged both <50 and ≥50 years, whereas family history of gastric cancer was associated with risk of CRN in participants aged <50 years (1.22; 1.14-1.30), but not in participants aged ≥50 years (1.08; 0.99-1.18).

CONCLUSIONS

Family history of gastric cancer was an independent risk factor for CRN, especially in those aged <50years. Persons with family histories of gastric cancer and CRC, especially those with family histories of both, may need to begin colonoscopy earlier.

GENOTYPE ASSOCIATION GSTM1 NULL AND GASTRIC CANCER: EVIDENCE-BASED META-ANALYSIS

BACKGROUND

Gastric cancer is the fourth most common cancer in men and the sixth among women, except for non-melanoma skin tumors, in Brazil. Epidemiological evidences reveal the multifactorial etiology of this cancer, highlighting risk factors such as: infection by the bacterium Helicobacter pylori, advanced age, smoking, chronic alcohol abuse, eating habits and genetic polymorphisms. Considering the context of genetic polymorphisms, there is the absence of the GSTM1 gene. The lack of GSTM1 function to detoxify xenobiotics and promote defense against oxidative stress leads to increased DNA damage, promoting gastric carcinogenesis. This process is multifactorial and the development of gastric cancer results from a complex interaction of these variables.

OBJECTIVE

The aim of this study was to investigate the association of GSTM1 null polymorphism in the pathogenesis of gastric cancer.

METHODS

A meta-analysis was conducted from 70 articles collected in SciELO and PubMed databases, between September 2015 and July 2016. In order to evaluate a possible association, we used the odds ratio (OR) and confidence interval of 95% (CI 95%). To assess the heterogeneity of the studies was used the chi-square test. Statistical analysis was performed using the BioEstat® 5.3.

RESULTS

This study included 70 studies of case-control, including 28,549 individuals, which were assessed for the null polymorphism of the GSTM1 gene, and of which 11,208 (39.26%) were cases and 17,341 (60.74%) were controls. The final analysis showed that the presence of the GSTM1 gene acts as a protective factor against the development of gastric cancer (OR=0.788; 95%CI 0.725-0.857; P<0.0001). Positive statistical association was found in Asia (OR=0.736; 95%CI 0.670-0.809; P<0.0001) and Eurasia (OR=0.671; 95%CI 0.456-0.988; P=0.05). However, statistically significant data was not obtained in Europe (OR=1.033; 95%CI 0.873-1.222; P=0.705) and America (OR=0.866; 95%CI 0.549-1.364; P=0.534). Therefore, the results can not be deduced around the world.

CONCLUSION

This meta-analysis concluded that the presence of the GSTM1 gene is a protector for the emergence of gastric cancer, especially in Asian countries, but this result was not found in Europe and America.

Comparison between Resectable Helicobacter pylori-Negative and -Positive Gastric Cancers

BACKGROUND/AIMS

Controversy exists regarding the characteristics of Helicobacter pylori infection-negative gastric cancer (HPIN-GC). The aim of this study was to evaluate clinicopathologic features of HPIN-GC compared to H. pylori infection-positive gastric cancer (HPIP-GC) using a comprehensive analysis that included genetic and environmental factors.

METHODS

H. pylori infection status of 705 resectable gastric cancer patients was determined by the rapid urease test, testing for anti-H. pylori antibodies, histologic analysis and culture of gastric cancer tissue samples, and history of H. pylori eradication. HPIN-GC was defined as gastric cancer that was negative for H. pylori infection based on all five methods and that had no evidence of atrophy in histology or serology.

RESULTS

The prevalence of HPIN-GC was 4% (28/705). No significant differences with respect to age, sex, smoking, drinking, family history of gastric cancer or obesity were observed between the two groups. HPIN-GC tumors were marginally more likely to involve the cardia (14.3% for HPIN-GC vs 5.3% for HPIP-GC, p=0.068). The Lauren classification, histology, and TNM stage did not differ according to H. pylori infection status. Microsatellite instability was not different between the two groups, but p53 overexpression in HPIN-GC was marginally higher than in HPIP-GC (56.0% for HPIN-GC vs 37.0% for HPIP-GC, p=0.055).

CONCLUSIONS

The prevalence of HPIN-GC was extremely low, and its clinicopathologic characteristics were similar to HPIP-GC.

Effect of Helicobacter pylori Eradication and ABO Genotype on Gastric Cancer Development

BACKGROUND

Evidence is lacking regarding how Helicobacter pylori infection status, eradication history, and ABO blood type affect the development of gastric cancer (GC) given the multifactorial and distinctive etiology according to cancer location (noncardia vs cardia) and histologic type (intestinal vs diffuse-type). We evaluated the effect of H. pylori infection status incorporated with H. pylori eradication history and ABO genotype on GC development according to cancer location and histologic type.

METHODS

A case-control study of 997 patients with noncardia GC (NCGC) and 1147 control subjects was performed using risk analyses with 14 factors including H. pylori infection with eradication history and ABO genotype. As final analyses, multivariable logistic regression models were fitted. Additionally, H. pylori infection status with eradication history was tested for its association with age, atrophic gastritis (AG), and intestinal metaplasia (IM).

RESULTS

The ABO genotype with the B allele was associated with a significantly lower risk of NCGC of both histologic types. The reduction in risk for NCGC by adding the B allele was more prominent in diffuse-type than that in the intestinal-type. H. pylori infection with eradication history was associated with a significantly lower risk of NCGC of both histologic types, compared with those without eradication history (odds ratio (OR), 0.22; 95% confidence interval (CI), 0.14-0.34) approaching that of uninfected subjects. Past infection status without an eradication history was associated with older age, AG, and IM.

CONCLUSIONS

H. pylori eradication and the B allele decreased the risks of the intestinal and diffuse-types of NCGC. H. pylori eradication revealed a strong association against developing NCGC. Therefore, it should be considered as a primary measure in NCGC prevention.

Xenobiotic Pathway Gene Polymorphisms Associated with Gastric Cancer in High Risk Mizo-Mongoloid Population, Northeast India

BACKGROUND

The aim of this study was to evaluate the risk of gastric cancer associated with individual or combined glutathione S-transferases (GSTs) polymorphism and their interaction with environmental factors.

MATERIALS AND METHODS

Genotyping by PCR was carried out for 80 cases and controls each for GSTM1, GSTT1, and GSTP1 polymorphism and mapped for gene-environment association studies. The samples were subjected to pathogen detection and GSTP1 expression for analyzing their association with different genotypes. Logistic regression analyses were conducted to compute the influence of both genetic and environmental factors for gastric cancer. MDR analysis was performed to assess the risk of gastric cancer by studying the gene-gene and gene-environment effect on the basis of GST genotyping and GSTP1 gene expression.

RESULTS

Infection with Helicobacter pylori and CagA+ strains was more frequent in patients with GSTM1/T1 null genotype. Intake of high fermented fat and smoked meat was found to be significantly associated with gastric cancer. The G/G, A/G (rs1695), and T/T (rs1138272) were found to be significantly associated with low expression of GSTP1 gene in cancer tissue.

CONCLUSION

Presence of H. pylori with CagA genotype showed significant individual effect with GSTT1 polymorphism as well as strong synergistic effect in gastric cancer risk. Majority of the gastric cancer samples showed significant negative expression in G/G, A/G (rs1695), and T/T (rs1138272) genotypes. This study shows that GST gene polymorphism was significantly relevant for determining the individual susceptibility to gastric cancer.

Waterpipe Tobacco Smoking and Gastric Cancer Risk among Vietnamese Men

BACKGROUND

The association of waterpipe tobacco (WPT) smoking with gastric cancer (GC) risk was suggested.

METHODS

A hospital-based case-control study was conducted to examine the association of WPT with GC risk among Vietnamese men, in Hanoi city, during the period of 2003-2011. Newly-diagnosed GC cases (n = 454) and control patients (n = 628) were matched by age (+/- 5 years) and the year of hospitalization. Information on smoking and alcohol drinking habits and diet including salty food intake and fruits/vegetables consumption were obtained by the interview. Maximum likelihood estimates of odds ratios (ORs) and corresponding 95% confidence intervals (Cis) were obtained using conditional logistic regression models.

RESULTS

The group with the highest consumption of citrus fruits showed a significantly low GC risk (OR = 0.6, 95%CI = 0.4-0.8, P for trend = 0.002). However, there was no association of raw vegetable consumption with GC risk. Referring to never smokers, GC risk was significantly higher in current WPT smokers (OR = 1.8, 95%CI = 1.3-2.4), and it was more evident in exclusively WPT smokers (OR = 2.7, 95%CI = 1.2-6.5). GC risk tended to be higher with daily frequency and longer duration of WPT smoking but these trends were not statistically significant (P for trend: 0.144 and 0.154, respectively). GC risk of those who started smoking WPT before the age of 25 was also significantly high (OR = 3.7, 95%CI = 1.2-11.3). Neither cigarette smoking nor alcohol drinking was related to GC risk.

CONCLUSION

The present findings revealed that WPT smoking was positively associated with GC risk in Vietnamese men.

Risks and Predictors of Gastric Adenocarcinoma in Patients with Gastric Intestinal Metaplasia and Dysplasia: A Population-Based Study

OBJECTIVES

Gastric intestinal metaplasia and dysplasia are precursor lesions for adenocarcinoma. The risks of progression to malignancy from these lesions are not well characterized, particularly in the US populations.

METHODS

We identified 4,331 Kaiser Permanente Northern California members who were diagnosed with gastric intestinal metaplasia or dysplasia between 1997 and 2006 and followed them through December 2013. The incident rates of gastric adenocarcinoma, relative risks in comparison with the Kaiser Permanente general population, and predictors of progression to malignancy were investigated.

RESULTS

Among 4,146 individuals with gastric intestinal metaplasia and 141 with low-grade dysplasia with 24,440 person-years follow-up, 17 and 6 cases of gastric adenocarcinoma were diagnosed, respectively, after 1 year from the index endoscopy. The incidence rate of gastric adenocarcinoma was 0.72/1,000 person-years in patients with intestinal metaplasia, with a relative risk of 2.56 (95% confidence interval (CI) 1.49-4.10) compared with the Kaiser Permanente member population, and 7.7/1,000 person-years for low-grade dysplasia, with a relative risk of 25.6 (95% CI, 9.4-55.7). The median time for gastric intestinal metaplasia to progress to adenocarcinoma was 6.1 years, and for low-grade dysplasia, 2.6 years. Hispanic race/ethnicity and history of dysplasia were associated with significantly higher risk of progression to gastric adenocarcinoma.

CONCLUSIONS

Gastric intestinal metaplasia and dysplasia are significant predictors for gastric adenocarcinoma. The low risk for malignancy associated with intestinal metaplasia does not support routine endoscopic surveillance. However, surveillance should be considered in patients at higher risks, including those with suspicious endoscopic features, presence of dysplasia, and Hispanic race/ethnicity.

Effect of Carrot Intake in the Prevention of Gastric Cancer: A Meta-Analysis

Purpose

Gastric cancer is the third leading cause of cancer-related mortality, with the incidence and mortality being higher in men than in women. Various studies have shown that eating carrots may play a major role in the prevention of gastric cancer. We conducted a meta-analysis to determine the relationship between carrot consumption and gastric cancer.

Materials and Methods

We searched multiple databases including PubMed, Cochrane Library, Scopus, ScienceDirect, and Persian databases like Scientific Information Database (SID) and IranMedx. The following search terms were used: stomach or gastric, neoplasm or cancer, carcinoma or tumor, and carrot. Statistical analyses were performed using Comprehensive Meta Analysis/2.0 software.

Results

We retrieved 81 articles by searching the databases. After considering the inclusion and exclusion criteria, 5 articles were included in this study. The odds ratio (OR) obtained by fixed effects model showed that a 26% reduction in the risk of gastric cancer has been associated with the consumption of carrots) OR=0.74; 95% confidence interval=0.68~0.81; P<0.0001). According to funnel graph, the results showed that the possibility of a publication bias does not exist in this study.

Conclusions

The findings of this study showed an inverse relationship between the consumption of carrots and the risk of gastric cancer.

Diagnosis and management of high risk group for gastric cancer

Gastric cancer is associated with high morbidity and mortality worldwide. To reduce the socioeconomic burden related to gastric cancer, it is very important to identify and manage high risk group for gastric cancer. In this review, we describe the general risk factors for gastric cancer and define high risk group for gastric cancer. We discuss strategies for the effective management of patients for the prevention and early detection of gastric cancer. Atrophic gastritis (AG) and intestinal metaplasia (IM) are the most significant risk factors for gastric cancer. Therefore, the accurate selection of individuals with AG and IM may be a key strategy for the prevention and/or early detection of gastric cancer. Although endoscopic evaluation using enhanced technologies such as narrow band imaging-magnification, the serum pepsinogen test, Helicobacter pylori serology, and trefoil factor 3 have been evaluated, a gold standard method to accurately select individuals with AG and IM has not emerged. In terms of managing patients at high risk of gastric cancer, it remains uncertain whether H. pylori eradication reverses and/or prevents the progression of AG and IM. Although endoscopic surveillance in high risk patients is expected to be beneficial, further prospective studies in large populations are needed to determine the optimal surveillance interval.

Worldwide Burden of Gastric Cancer Attributable to Tobacco Smoking in 2012 and Predictions for 2020

BACKGROUND

The heterogeneous patterns and trends in tobacco consumption contribute to regional and gender differences in the burden of gastric cancer attributable to smoking.

AIMS

To estimate the proportion and absolute number of gastric cancer cases that can be attributed to smoking in different countries, in 2012 and 2020.

METHODS

Population attributable fractions (PAFs) were computed for 118 countries, using data of smoking prevalence in 2002 and 2011 and published estimates of the magnitude of the association between smoking and gastric cancer, assuming a time lag of ≈10 years.

RESULTS

For men, the highest PAF estimates in 2012 were observed in Eastern Asia and the lowest in North America, whereas for women the highest were in Western Europe and the lowest in Africa. Very high Human Development Index (HDI) countries presented the lowest median PAF in men (very high vs. high, medium, and low HDI: 17.2 vs. 20.8 %, p = 0.014) and the highest median PAF in women (very high vs. high, medium, and low HDI: 4.3 vs. 1.8 %, p < 0.001). Estimates for 2020 show a decrease in median PAFs, but the estimated absolute number of cases attributable to smoking in the countries analyzed increased for men (≈154,000 vs. ≈160,000) and decreased for women (≈6200 vs. ≈5600).

CONCLUSIONS

Smoking accounts for a larger number of gastric cancer cases among men, and gender differences are expected to increase in the next decade, despite the decrease in PAFs. Intensified efforts to control smoking are needed to further reduce the burden of gastric cancer.

Association of risk of gastric cancer and consumption of tobacco, alcohol and tea in the Chinese population

This study aimed at summarizing epidemiological research findings on associations between tobacco, alcohol and tea consumption and risk of gastric cancer (GC) in the Chinese population. The review searched PubMed, Embase, China National Knowledge Infrastructure (CNKI) and China Biology Medicine (CBM) databases and reference lists of review papers for all studies published in English or Chinese languages. Information extracted, via two independent researchers, from retrieved articles included first author, year of publication, study design, sample size, source of controls and adjusted odds ratio (OR) or relative risk (RR) with the corresponding 95% confidence intervals (CIs) for each category. Statistical analyses used software STATA version 12.0. The systematic search found 89 articles containing 25,821 GC cases and 135,298 non-cases. The overall random effects in terms of pooled OR and 95%CI for tobacco, alcohol and tea consumption were 1.62 (95%CI: 1.50-1.74), 1.57 (95%CI: 1.41-1.76) and 0.67 (95%CI: 0.59-0.76) respectively; while the heterogeneity among included studies ranged from 80.1% to 87.5%. The majority of subgroup analyses revealed consistent results with the overall analyses. All three behavioral factors showed statistically significant dose-dependent effects on GC (P<0.05). The study revealed that tobacco smoking and alcohol drinking were associated with over 1/2 added risk of GC, while tea drinking conferred about 1/3 lower risk of GC in the Chinese population. However, these results should be interpreted with caution given the fact that most of the included studies were based on a retrospective design and heterogeneity among studies was relatively high.

Helicobacter pylori-negative gastric cancer: characteristics and endoscopic findings

Helicobacter pylori (H. pylori) leads to chronic gastritis and eventually causes gastric cancer. The prevalence of H. pylori infection is gradually decreasing with improvement of living conditions and eradication therapy. However, some reports have described cases of H. pylori-negative gastric cancers (HpNGC), and the prevalence was 0.42-5.4% of all gastric cancers. Diagnostic criteria of HpNGC vary among the different reports; thus, they have not yet been definitively established. We recommend negative findings in two or more methods that include endoscopic or pathological findings or serum pepsinogen test, and negative urease breath test or serum immunoglobulin G test and no eradication history the minimum criteria for diagnosis of HpNGC. The etiology of gastric cancers, excluding H. pylori infection, is known to be associated with several factors including lifestyle, viral infection, autoimmune disorder and germline mutations, but the main causal factor of HpNGC is still unclear. Regarding the characteristics of HpNGC, the undifferentiated type (UD-type) is more frequent than the differentiated type (D-type). The UD-type is mainly signet ring-cell carcinoma that presents as a discolored lesion in the lower or middle part of the stomach in relatively young patients. The gross type is flat or depressed. The D-type is mainly gastric adenocarcinoma of the fundic gland type that presents as a submucosal tumor-like or flat or depressed lesion in the middle and upper part of the stomach in relatively older patients. Early detection of HpNGC enables minimally invasive treatment which preserves the patient's quality of life. Endoscopists should fully understand the characteristics and endoscopic findings of HpNGC.

Association between the expression of T-cadherin and vascular endothelial growth factor and the prognosis of patients with gastric cancer

T-cadherin has been identified as a tumor-suppressor gene in several types of cancer. The present study aimed to investigate the association of the expression of T-cadherin with angiogenesis, and to evaluate its prognostic value for patients with primary gastric cancer. Gastric cancer tissues and matched adjacent tissues from 166 patients receiving surgical resection were included in the present study. The expression of T-cadherin was detected using immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction. The expression of vascular epidermal growth factor (VEGF) was detected using immunohistochemistry, and its association with the expression of T-cadherin was analyzed. In addition, the association between the expression of T-cadherin and clinicopathological features were analyzed. The mRNA and protein expression levels of T-cadherin were significantly lower in the gastric cancer tissue compared with the corresponding adjacent normal tissue (P<0.05). The expression of VEGF was not associated with the expression of T-cadherin in the gastric cancer tissue. The decreased protein expression of T-cadherin correlated with smoking, larger tumor size (diameter, >4 cm), lymph node metastasis and a higher tumor-lymph node-metastasis stage (P<0.05 or P<0.01). However, the expression of T-cadherin was not correlated with gender, age, alcohol intake, Helecobacter pylori infection or differentiation (P>0.05). The multivariate analysis demonstrated that the expression of T-cadherin was an independent prognostic factor for the overall survival rate of patients with gastric cancer. This data suggested that the downregulation of T-cadherin may contribute to gastric cancer progression, representing a useful biomarker for predicting the biological behavior and prognosis of gastric cancer. However, no significant association was observed between the expression of VEGF and T-cadherin.

Development and validation of risk prediction algorithms to estimate future risk of common cancers in men and women: prospective cohort study

OBJECTIVE

To derive and validate a set of clinical risk prediction algorithm to estimate the 10-year risk of 11 common cancers.

DESIGN

Prospective open cohort study using routinely collected data from 753 QResearch general practices in England. We used 565 practices to develop the scores and 188 for validation.

SUBJECTS

4.96 million patients aged 25-84 years in the derivation cohort; 1.64 million in the validation cohort. Patients were free of the relevant cancer at baseline.

METHODS

Cox proportional hazards models in the derivation cohort to derive 10-year risk algorithms. Risk factors considered included age, ethnicity, deprivation, body mass index, smoking, alcohol, previous cancer diagnoses, family history of cancer, relevant comorbidities and medication. Measures of calibration and discrimination in the validation cohort.

OUTCOMES

Incident cases of blood, breast, bowel, gastro-oesophageal, lung, oral, ovarian, pancreas, prostate, renal tract and uterine cancers. Cancers were recorded on any one of four linked data sources (general practitioner (GP), mortality, hospital or cancer records).

RESULTS

We identified 228,241 incident cases during follow-up of the 11 types of cancer. Of these 25,444 were blood; 41,315 breast; 32,626 bowel, 12,808 gastro-oesophageal; 32,187 lung; 4811 oral; 6635 ovarian; 7119 pancreatic; 35,256 prostate; 23,091 renal tract; 6949 uterine cancers. The lung cancer algorithm had the best performance with an R(2) of 64.2%; D statistic of 2.74; receiver operating characteristic curve statistic of 0.91 in women. The sensitivity for the top 10% of women at highest risk of lung cancer was 67%. Performance of the algorithms in men was very similar to that for women.

CONCLUSIONS

We have developed and validated a prediction models to quantify absolute risk of 11 common cancers. They can be used to identify patients at high risk of cancers for prevention or further assessment. The algorithms could be integrated into clinical computer systems and used to identify high-risk patients.

WEB CALCULATOR

There is a simple web calculator to implement the Qcancer 10 year risk algorithm together with the open source software for download (available at http://qcancer.org/10yr/).

Glutathione S-transferase gene GSTM1, gene-gene interaction, and gastric cancer susceptibility: evidence from an updated meta-analysis

Background

The null genotype of GSTM1 have been implicated in gastric cancer risk, but numerous individual studies showed mixed, or even conflicting results. Thus, a meta-analysis was performed.

Results

We identified 54 individual studies involving 9,322 cases and 15,118 controls through computer-based searches of PubMed, Embase, and Cochrane Library. It was found that the null genotype of GSTM1 was associated with an increased gastric cancer risk (OR = 1.207, 95% CI: 1.106-1.317, P < 0.001), under the random-effects model (I² : 49.9%, P_Q <0.001). From stratification analyses for ethnicity, alcohol drinking, Helicobacter pylori infection, an effect modification of gastric cancer risk was found in the subgroups of ethnicity, smoking status, Helicobacter pylori infection, whereas null result was found in the subgroups of alcohol drinking. We also undertook gene-gene interaction analysis between GSTM1 and GSTT1 genes for gastric cancer risk, and the results indicated that the dual null genotypes of GSTM1 and GSTT1 might elevate the risk of gastric cancer (OR = 1.505, 95% CI: 1.165-1.944, P = 002).

Conclusions

This meta-analysis suggests that the null genotype of GSTM1 may be a important genetic risk factor for gastric cancer development.

Risk factors of atrophic gastritis and intestinal metaplasia in first-degree relatives of gastric cancer patients compared with age-sex matched controls

Background:

To identify whether first-degree relatives (FDRs) of gastric cancer (GC) patients have increased risk for atrophic gastritis (AG) and intestinal metaplasia (IM) in relation to other risk factors of GC.

Methods:

The study cohort consisted of 224 pairs of age-sex matched controls and FDRs. AG and IM in the gastric mucosa were scored histologically using the updated Sydney classification. Risk of having AG and IM was studied by comparing FDRs to controls. Impacts of age, H. pylori infection, smoking, dietary and socioeconomic factors on the presence of AG and IM were studied.

Results:

In multivariate regression analysis, FDRs had adjusted OR of 2.69 (95% CI 1.06–6.80, P=0.037) for antral IM in male population. Adjusted OR for antral AG and IM were 9.28 (95% CI 4.73–18.18, P<0.001) and 7.81 (95% CI 3.72–16.40, P<0.001) for the H. pylori infected subjects in total population. Getting old by 5 years increased the ORs of having AG and IM by approximately 1.25 fold (P<0.001). Spicy food increased the OR of antral IM by 2.28 fold (95% CI 1.36–3.84, P=0.002).

Conclusions:

Family history of GC was an independent risk factor for antral IM in male in our study, which could be one reason for the increase of gastric cancer in the family member of gastric cancer. It could be an evidence for the necessity of frequent endoscopy in the presence of family history of GC compared to general population in male.

Virulence Factors of Helicobacter pylori: A Review

Helicobacter pylori is a spiral-shaped Gram-negative bacterium that colonizes the human stomach and can establish a long-term infection of the gastric mucosa, a condition that affects the relative risk of developing various clinical disorders of the upper gastrointestinal tract, such as chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma. H. pylori presents a high-level of genetic diversity, which can be an important factor in its adaptation to the host stomach and also for the clinical outcome of infection. There are important H. pylori virulence factors that, along with host characteristics and the external environment, have been associated with the different occurrences of diseases. This review is aimed to analyzing and summarizing the main of them and possible associations with the clinical outcome.

Case-case comparison of smoking and alcohol risk associations with Epstein-Barr virus-positive gastric cancer

Helicobacter pylori is the primary cause of gastric cancer. However, monoclonal Epstein-Barr virus (EBV) nucleic acid is also present in up to 10% of these tumors worldwide. EBV prevalence is increased with male sex, nonantral localization and surgically disrupted anatomy. To further examine associations between EBV and gastric cancer, we organized an international consortium of 11 studies with tumor EBV status assessed by in situ hybridization. We pooled individual-level data on 2,648 gastric cancer patients, including 184 (7%) with EBV-positive cancers; all studies had information on cigarette use (64% smokers) and nine had data on alcohol (57% drinkers). We compared patients with EBV-positive and EBV-negative tumors to evaluate smoking and alcohol interactions with EBV status. To account for within-population clustering, multilevel logistic regression models were used to estimate interaction odds ratios (OR) adjusted for distributions of sex (72% male), age (mean 59 years), tumor histology (56% Lauren intestinal-type), anatomic subsite (61% noncardia) and year of diagnosis (1983-2012). In unadjusted analyses, the OR of EBV positivity with smoking was 2.2 [95% confidence interval (CI) 1.6-3.2]. The OR was attenuated to 1.5 (95% CI 1.01-2.3) by adjustment for the possible confounders. There was no significant interaction of EBV status with alcohol drinking (crude OR 1.4; adjusted OR 1.0). Our data indicate the smoking association with gastric cancer is stronger for EBV-positive than EBV-negative tumors. Conversely, the null association with alcohol does not vary by EBV status. Distinct epidemiologic characteristics of EBV-positive cancer further implicate the virus as a cofactor in gastric carcinogenesis.

Quantitative assessment of the influence of prostate stem cell antigen polymorphisms on gastric cancer risk

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol-anchored 123-amino acid protein related to the cell proliferation inhibition and/or cell death induction activity which has attracted considerable attention as a candidate gene for gastric cancer (GC) since it was first identified through genome-wide association approach. Since then, the relationship between PSCA polymorphisms (rs2294008, rs2976392) and GC has been reported in various ethnic groups; however, these studies have yielded inconsistent results. To investigate this inconsistency, we performed a meta-analysis of 16 studies involving a total of 18,820 cases and 35,756 controls for the two widely studied polymorphisms of PSCA on genetic susceptibility for GC. Overall, the summary odds ratio for GC was 1.46 (95% CI 1.30-1.69, P < 10(-5)) and 1.49 (95% CI 1.22-1.82, P < 10(-4)) for PSCA rs2294008 and rs2976392 polymorphisms, respectively. Meanwhile, haplotype analyses of the two polymorphisms revealed a significant association between the combination of these alleles and GC risk. When stratifying for ethnicity, significantly increased risks were found for rs2294008 and rs2976392 polymorphism among East Asians in all genetic models, while no significant associations were observed for the rs2294008 polymorphism in Caucasians. In the stratified analyses according to histological type, and source of controls, evidence of gene-disease association was still obtained. In addition, our data indicate that rs2294008 of PSCA is involved in GC susceptibility and confer its effect primarily in noncardia tumors (OR = 1.30, 95% CI 1.12-1.53, P < 10(-4)). Our findings demonstrated that rs2294008 and rs2976392 polymorphism of PSCA is a risk-conferring factor associated with increased GC susceptibility, especially in East Asians.

Trend of mortality rates for gastric cancer in Brazil and regions in the period of 30 years (1980-2009)

CONTEXT

The most recent global estimate revealed the presence of about one million new cases of stomach cancer for the year 2008, setting itself as the fourth most common cause of cancer.

OBJECTIVE

The present study aims to assess the trend of mortality from stomach cancer in Brazil according to regions between 1980 and 2009.

METHODS

Data on deaths from stomach cancer were obtained from the Mortality Information System, and the demographic data, from the Brazilian Institute of Geography and Statistics. The rates of mortality were standardized by age according to world population. The trend curves were calculated for Brazilian regions by sex. The technique used was polynomial regression and joinpoint.

RESULTS

The tendency for males and females is similar in all regions, although the magnitude is higher among men in all places. Regions Midwest, South, Southeast tended to decline, while the Northern region showed no significant trend, and the Northeast tended to increase.

CONCLUSION

It is therefore a need to evaluate public health policies for gastric cancer aimed at the demographic transition (change of urbanization and lifestyle) that is occurring throughout the country.

Risk factors for gastric cancer in Latin America: a meta-analysis

BACKGROUND

Latin America has among the highest gastric cancer incidence rates in the world, for reasons that are still unknown. In order to identify region-specific risk factors for gastric cancer, we conducted a meta-analysis summarizing published literature.

METHODS

Searches of PubMed and regional databases for relevant studies published up to December 2011 yielded a total of 29 independent case-control studies. We calculated summary odds ratios (OR) for risk factors reported in at least five studies, including socioeconomic status (education), lifestyle habits (smoking and alcohol use), dietary factors (consumption of fruits, total vegetables, green vegetables, chili pepper, total meat, processed meat, red meat, fish, and salt), and host genetic variants (IL1B-511T, IL1B-31C, IL1RN*2, TNFA-308A, TP53 codon 72 Arg, and GSTM1 null). Study-specific ORs were extracted and summarized using random-effects models.

RESULTS

Chili pepper was the only region-specific factor reported in at least five studies. Consistent with multifactorial pathogenesis, smoking, alcohol use, high consumption of red meat or processed meat, excessive salt intake, and carriage of IL1RN*2 were each associated with a moderate increase in gastric cancer risk. Conversely, higher levels of education, fruit consumption, and total vegetable consumption were each associated with a moderately decreased risk. The other exposures were not significantly associated. No prospective study data were identified.

CONCLUSION

Risk factor associations for gastric cancer in Latin America are based on case-control comparisons that have uncertain reliability, particularly with regard to diet; the specific factors identified and their magnitudes of association are largely similar to those globally recognized. Future studies should emphasize prospective data collection and focus on region-specific exposures that may explain high gastric cancer risk.

Genetic testing by cancer site: stomach

Gastric cancer is a global public health concern, ranking as the fourth leading cause of cancer mortality, with a 5-year survival of only 20%. Approximately 10% of gastric cancers appear to have a familial predisposition, and about half of these can be attributed to hereditary germline mutations. We review the genetic syndromes and current standards for genetic counseling, testing, and medical management for screening and treatment of gastric cancer. Recently, germline mutations in the E-cadherin/CDH1 gene have been identified in families with an autosomal dominant inherited predisposition to gastric cancer of the diffuse type. The cumulative lifetime risk of developing gastric cancer in CDH1 mutation carriers is up to 80%, and women from these families also have an increased risk for developing lobular breast cancer. Prophylactic gastrectomies are recommended in unaffected CDH1 mutation carriers, because screening endoscopic examinations and blind biopsies have proven inadequate for surveillance. In addition to this syndrome, gastric cancer risk is elevated in Lynch syndrome associated with germline mutations in DNA mismatch repair genes and microsatellite instability, in hereditary breast and ovarian cancer syndrome due to germline BRCA1 and BRCA2 mutations, in familial adenomatous polyposis caused by germline APC mutations, in Li-Fraumeni syndrome due to germline p53 mutations, in Peutz-Jeghers syndrome associated with germline STK11 mutations, and in juvenile polyposis syndrome associated with germline mutations in the SMAD4 and BMPR1A genes. Guidelines for genetic testing, counseling, and management of individuals with hereditary diffuse gastric cancer are suggested. A raised awareness among the physician and genetic counseling communities regarding these syndromes may allow for increased detection and prevention of gastric cancers in these high-risk individuals.

Overview of methodological quality of systematic reviews about gastric cancer risk and protective factors

BACKGROUND AND OBJECTIVE

A comprehensive overall review of gastric cancer (GC) risk and protective factors is a high priority, so we conducted the present study.

METHODS

Systematic searches in common medical electronic databases along with reference tracking were conducted to include all kinds of systematic reviews (SRs) about GC risk and protective factors. Two authors independently selected studies, extracted data, and evaluated the methodological qualities and the quality of evidence using R-AMSTAR and GRADE approaches.

RESULTS

Beta- carotene below 20 mg/day, fruit, vegetables, non-fermented soy-foods, whole-grain, and dairy product were GC protective factors, while beta-carotene 20 mg/day or above, pickled vegetables, fermented soy-foods, processed meat 30 g/d or above, or salty foods, exposure to alcohol or smoking, occupational exposure to Pb, overweight and obesity, helicobacter pylori infection were GC risk factors. So we suggested screening and treating H. pylori infection, limiting the amount of food containing risk factors (processed meat consumption, beta-carotene, pickled vegetables, fermented soy-foods, salty foods, alcohol), stopping smoking, avoiding excessive weight gain, avoidance of Pb, and increasing the quantity of food containing protective components (fresh fruit and vegetables, non-fermented soy-foods, whole-grain, dairy products).

CONCLUSIONS

The conclusions and recommendations of our study were limited by including SRs with poor methodological bases and low quality of evidence, so that more research applying checklists about assessing the methodological qualities and reporting are needed for the future.

Relevance of GSTM1, GSTT1, and GSTP1 gene polymorphisms to gastric cancer susceptibility and phenotype

Human glutathione S-transferases (GSTs) are phase II metabolizing enzymes that play a key role in protecting against cancer by detoxifying numerous potentially cytotoxic/genotoxic compounds. The genes encoding the human GST isoenzymes GSTM(mu)1, GSTT(theta)1 and GSTP(pi)1 harbour polymorphisms, which have been considered important modifiers of the individual risk for environmentally induced cancers such as gastric cancer (GC). However, results are inconsistent among studies from different geographic areas and ethnic groups. Our goal was to perform a nationwide, case-control study in Spain to evaluate the relevance of several functional GST gene polymorphisms and environmental factors to GC risk and phenotype. DNA from 557 GC patients and 557 sex- and age-matched healthy controls (HC) was typed for two deletions in the GSTM1 and GSTT1 genes and two SNPs in the GSTP1 gene (rs1695 and rs1138272) using polymerase chain reaction-restriction fragment length polymorphism methods. Logistic regression analysis identified Helicobacter pylori infection with CagA strains [odds ratio (OR): 2.36; 95% confidence interval (CI): 1.78-3.15], smoking habit (OR: 2.10; 95% CI: 1.48-2.97) and family history of GC (OR: 3.2; 95% CI: 2.02-5.16) as independent risk factors for GC. No differences in the frequencies of GSTM1 or GSTT1 null genotypes were observed between cases and controls (GSTM1: 50.8% vs. 48%; GSTT1: 21.5% vs. 21%). Moreover, simultaneous carriage of both, the GSTM1 and the GSTT1 null genotypes, was almost identical in both groups (10.7% in GC vs. 10.6% in HC). In addition, no significant differences in GSTP1 Ile105Val (rs1695) and GSTP1 Val114Ala (rs1138272) genotype distribution were observed between GC patients and controls. Subgroup analysis for age, gender, Helicobacter pylori status, smoking habits, family history of GC, anatomic location and histological subtype revealed no significant association between GST variants and GC risk. Our results show that the GST polymorphisms evaluated in this study are not relevant when determining the individual susceptibility to GC or phenotype in a South-European population.

Meta-analysis of the association of CYP1A1 polymorphisms with gastric cancer susceptibility and interaction with tobacco smoking

The association of two cytochrome P4501A1 (CYP1A1) polymorphisms, m1 (T6235C transition) and m2 (A4889G transition), with gastric cancer risk is inconclusive. We conducted a meta-analysis of all available studies to evaluate the potential role of the polymorphisms and their interactions with tobacco smoking in gastric cancer susceptibility. Published literature from PubMed was retrieved by two investigators independently. Fourteen case-control studies with 2,032 gastric cancer cases and 5,099 controls were selected. A fixed effects model or a random-effects model was used to estimate the odds ratio (OR) for the CYP1A1 polymorphisms and the occurrence of gastric cancer. Significant associations between CYP1A1 m1 and m2 polymorphisms and gastric cancer susceptibility were not observed in all genetic models in the overall analyses. Subgroup analyses by ethnicity and source of controls did not reveal significant associations with gastric cancer risk. Stratification analysis by smoking status found that carriers of the heterozygous and homozygous m1 genotypes decreased the susceptibility of gastric cancer among ever-smokers (pooled OR = 0.56, 95 % CI 0.36-0.89, fixed effects). In contrast, the m2 genotypes (G/G and A/G) did not show any relevance to gastric cancer risk among the smoking population (pooled OR = 1.30, 95 % CI 0.84-2.00, fixed effects). Overall, we found that the CYP1A1 polymorphism itself, either m1 or m2, did not represent an independent genetic risk factor influencing gastric cancer. However, subgroup analyses suggest that carriers of the heterozygous and homozygous m1 genotype who are exposed to tobacco smoke have a significantly lower risk of developing gastric cancer. To explain the observed reduction of gastric cancer risk, we proposed a novel hypothesis of "observation bias". This hypothesis is also applicable to explain the combined effects of other genetic polymorphisms and environmental factors on the risk of developing cancers, and the rationality of the hypothesis needs to be further investigated.