Role of Helicobacter pylori CagA+ strains and risk of adenocarcinoma of the stomach and esophagus

Immune response modulation in inflammatory bowel diseases by Helicobacter pylori infection

Many studies point to an association between Helicobacter pylori (H. pylori) infection and inflammatory bowel diseases (IBD). Although controversial, this association indicates that the presence of the bacterium somehow affects the course of IBD. It appears that H. pylori infection influences IBD through changes in the diversity of the gut microbiota, and hence in local chemical characteristics, and alteration in the pattern of gut immune response. The gut immune response appears to be modulated by H. pylori infection towards a less aggressive inflammatory response and the establishment of a targeted response to tissue repair. Therefore, a T helper 2 (Th2)/macrophage M2 response is stimulated, while the Th1/macrophage M1 response is suppressed. The immunomodulation appears to be associated with intrinsic factors of the bacteria, such as virulence factors - such oncogenic protein cytotoxin-associated antigen A, proteins such H. pylori neutrophil-activating protein, but also with microenvironmental changes that favor permanence of H. pylori in the stomach. These changes include the increase of gastric mucosal pH by urease activity, and suppression of the stomach immune response promoted by evasion mechanisms of the bacterium. Furthermore, there is a causal relationship between H. pylori infection and components of the innate immunity such as the NLR family pyrin domain containing 3 inflammasome that directs IBD toward a better prognosis.

Effects of infections on the pathogenesis of cancer

Several studies have shown an inverse relationship between acute infections and cancer development. On the other hand, there is a growing evidence that chronic infections may contribute significantly to the carcinogenesis. Factors responsible for increased susceptibility to infections may include modifications of normal defence mechanisms or impairment of host immunity due to altered immune function, genetic polymorphisms, ageing and malnourishment. Studies have demonstrated that children exposed to febrile infectious diseases show a subsequent reduced risk for ovarian cancer, melanoma and many other cancers, while common acute infections in adults are associated with reduced risks for melanoma, glioma, meningioma and multiple cancers. Chronic inflammation associated with certain infectious diseases has been suggested as a cause for the development of tumours. Mechanisms of carcinogenesis due to infections include cell proliferation and DNA replication by mitogen-activated protein kinase pathway, production of toxins that affect the cell cycle and lead to abnormal cell growth and inhibition of apoptosis. This review was aimed to summarize the available evidence on acute infections as a means of cancer prevention and on the role of chronic infections in the development and progression of cancer.

Helicobacter pylori healthy South Asians

We aimed to estimate the pooled prevalence of Helicobacter pylori among asymptomatic South Asians based on available literature and highlight the importance of screening asymptomatic individuals and implementing preventive strategies for eradicating H. pylori. Electronic databases such as PubMed and Embase, a regional database of WHO South Asian Region, and gray literature sites were searched for relevant studies from 1983 to 5 May 2020. In addition, references of the included studies were thoroughly searched. The random-effect model was used to calculate the pooled prevalence with a 95% confidence interval (CI) along with subgroup analysis. Analysis of 19 studies showed a pooled prevalence of 56.5%, ranging from 10.3 to 91.7%. In subgroup analysis by country, the highest prevalence rate was reported from Bangladesh (86.3%, 95% CI: 0.806-0.921), whereas the lowest prevalence was from Sri Lanka (10.3%, 95% CI: 0.072-0.135). No differences were found between males and females. Prevalence among children and adolescents was 65.3% (95% CI: 0.529-0.777), greater than adults, 56.9% (95% CI: 0.353-0.785). The prevalence rate showed a decreasing trend upon comparison of studies conducted before and after 2000. Our analysis reveals the high prevalence of H. pylori infection among asymptomatic healthy populations in South Asia, particularly in children and adolescents. Public health awareness and sanitation interventions, pure drinking water, and respective strategies on a policy level to eradicate H. pylori and additional extensive multicentric cohort studies are necessary.

Narrative review of the role of gastroenterologist in the diagnosis, treatment and palliation in gastric and gastroesophageal cancer

Esophageal cancer (EC) and gastric cancer (GC) carry a high mortality rate. Unfortunately, a majority of patients are asymptomatic and at the time of diagnosis, the disease may invariably be in its advanced stages with limited curative options. Thus, it is imperative to recognize certain risk factors including gastroesophageal reflux disease (GERD), male gender, pre-existing Barrett’s esophagus, smoking history, obesity, Helicobacter pylori infection, atrophic gastritis among others for both EC and GC, intervene on time with screening and surveillance modalities if indicated and optimize treatment plans. With advances in endoscopic techniques, early neoplastic lesions are increasingly managed by gastroenterologists, offering an alternative to surgery. The gold standard for diagnosis of EC and GC is high definition endoscopy with adequate targeted biopsies. Endoscopic ultrasound (EUS) is a key in the staging of early cancers dictating the pathway for treatment options. We also play a key role in palliation cases with the aim to reduce the symptoms like nausea, vomiting and even when possible, restore oral intake and improve nutrition in both advanced GC and EC. This review article discusses the risk factors, diagnostic and endoscopic treatment modalities of early EC and GC and palliation of advanced cancer where gastroenterologists play a key role.

Helicobacter pylori eradication for the prevention of gastric neoplasia

BACKGROUND

Gastric cancer is the third most common cause of cancer death worldwide. Individuals infected with Helicobacter pylori have a higher likelihood of developing gastric cancer than individuals who are not infected. Eradication of H. pylori in healthy asymptomatic individuals in the general population may reduce the incidence of gastric cancer, but the magnitude of this effect is unclear.

OBJECTIVES

To assess the effectiveness of eradication of H. pylori in healthy asymptomatic individuals in the general population in reducing the incidence of gastric cancer.

SEARCH METHODS

We identified trials by searching the Cochrane Central Register of Controlled Trials (CENTRAL; 2020, Issue 1), MEDLINE (1946 to February 2020), and EMBASE (1974 to February 2020). We handsearched reference lists from trials selected by electronic searching to identify further relevant trials. We handsearched published abstracts from conference proceedings from the United European Gastroenterology Week (published in Gut) and Digestive Disease Week (published in Gastroenterology) between 2001 and 2019. We contacted members of the Cochrane Upper Gastrointestinal and Pancreatic Diseases Review Group and experts in the field and asked them to provide details of outstanding clinical trials and any relevant unpublished materials.

SELECTION CRITERIA

We analysed randomised controlled trials comparing at least one week of H. pylori therapy with placebo or no treatment in preventing subsequent development of gastric cancer in otherwise healthy and asymptomatic H. pylori-positive adults. Trials had to follow up participants for at least two years and needed to have at least two participants with gastric cancer as an outcome. We defined gastric cancer as any gastric adenocarcinoma, including intestinal (differentiated) or diffuse (undifferentiated) type, with or without specified histology.

DATA COLLECTION AND ANALYSIS

We collected data on incidence of gastric cancer, incidence of oesophageal cancer, deaths from gastric cancer, deaths from any cause, and adverse effects arising due to therapy.

MAIN RESULTS

Six trials met all our eligibility criteria and provided extractable data in the previous version. Following our updated search, one new RCT was identified, meaning that seven trials were included in this updated review. In addition, one previously included trial provided fully published data out to 10 years, and another previously included trial provided fully published data out to 22 years of follow-up. Four trials were at low risk of bias, one trial was at unclear risk, and two trials were at high risk of bias. Six trials were conducted in Asian populations. In preventing development of subsequent gastric cancer, H. pylori eradication therapy was superior to placebo or no treatment (RR 0.54, 95% confidence interval (CI) 0.40 to 0.72, 7 trials, 8323 participants, moderate certainty evidence). Only two trials reported the effect of eradication of H. pylori on the development of subsequent oesophageal cancer. Sixteen (0.8%) of 1947 participants assigned to eradication therapy subsequently developed oesophageal cancer compared with 13 (0.7%) of 1941 participants allocated to placebo (RR 1.22, 95% CI 0.59 to 2.54, moderate certainty evidence). H. pylori eradication reduced mortality from gastric cancer compared with placebo or no treatment (RR 0.61, 95% CI 0.40 to 0.92, 4 trials, 6301 participants, moderate certainty evidence). There was little or no evidence in all-cause mortality (RR 0.97, 95% CI 0.85 to 1.12, 5 trials, 7079 participants, moderate certainty evidence). Adverse events data were poorly reported.

AUTHORS' CONCLUSIONS

We found moderate certainty evidence that searching for and eradicating H. pylori reduces the incidence of gastric cancer and death from gastric cancer in healthy asymptomatic infected Asian individuals, but we cannot necessarily extrapolate this data to other populations.

One Size Does Not Fit All: Marked Heterogeneity in Incidence of and Survival from Gastric Cancer among Asian American Subgroups

BACKGROUND

Asian Americans are at higher risk for noncardia gastric cancers (NCGC) relative to non-Hispanic Whites (NHW). Asian Americans are genetically, linguistically, and culturally heterogeneous, yet have mostly been treated as a single population in prior studies. This aggregation may obscure important subgroup-specific cancer patterns.

METHODS

We utilized data from 13 regional United States cancer registries from 1990 to 2014 to determine secular trends in incidence and survivorship from NCGC. Data were analyzed for NHWs and the six largest Asian American subgroups: Chinese, Japanese, Filipino, Korean, Vietnamese, and South Asian (Indian/Pakistani).

RESULTS

There exists substantial heterogeneity in NCGC incidence between Asian subgroups, with Koreans (48.6 per 100,000 person-years) having seven-fold higher age-adjusted incidence than South Asians (7.4 per 100,000 person-years). Asians had generally earlier stages of diagnosis and higher rates of surgical resection compared with NHWs. All Asian subgroups also demonstrated higher 5-year observed survival compared with NHWs, with Koreans (41.3%) and South Asians (42.8%) having survival double that of NHWs (20.1%, P < 0.001). In multivariable regression, differences in stage of diagnosis and rates of resection partially explained the difference in survivorship between Asian subgroups.

CONCLUSIONS

We find substantial differences in incidence, staging, histology, treatment, and survivorship from NCGC between Asian subgroups, data which challenge our traditional perceptions about gastric cancer in Asians. Both biological heterogeneity and cultural/environmental differences may underlie these findings.

IMPACT

These data are relevant to the national discourse regarding the appropriate role of gastric cancer screening, and identifies high-risk racial/ethnic subgroups who many benefit from customized risk attenuation programs.

Helicobacter pylori Is Associated With Precancerous and Cancerous Lesions of the Gastric Cardia Mucosa: Results of a Large Population-Based Study in China

Background: Helicobacter pylori (H. pylori) is widely accepted to be the most important cause of gastric non-cardia adenocarcinoma (GNCA), while its role in the development of gastric cardia adenocarcinoma (GCA) is not well-defined. We aimed to investigate current H. pylori infection in relation to the severity of both precancerous and cancerous lesions of the gastric cardia in an Asian population at high risk of GCA. Methods: A population-based cross-sectional study was conducted in Linzhou County, Henan Province, China. Two thousand three (2,003) randomly selected participants with data on current H. pylori infection, assayed by 13C-urea breath test (13C-UBT), and a sequence of histological diagnoses of the gastric cardia mucosa were analyzed. Results: Of 2,003 subjects, 828 (41.33%) were currently infected with H. pylori. The prevalence of current H. pylori infection increased with increasing severity of histological lesions, from 34.12% in subjects with normal gastric cardia mucosa to 52.17% in subjects with gastric cardia high-grade intraepithelial neoplasia (CHIN)/ gastric cardia adenocarcinoma (GCA) (P for trend <0.001). With H. pylori-negative subjects as the reference category, H. pylori-positive subjects had statistically significant elevated adjusted prevalence odds ratios (PORs) for each of the histological lesions. The PORs (95% CI) were 2.15 (1.74-2.64), 3.46 (2.08-5.75), 2.78 (1.90-4.07), and 3.05 (1.30-7.17) for subjects with carditis, cardia intestinal metaplasia (CIM), cardia low-grade intraepithelial neoplasia (CLIN), and CHIN/GCA), respectively. The associations remained when subjects with abnormal stomach non-cardia mucosa were excluded. Conclusions: This large epidemiologic study demonstrates a positive association between current H. pylori infection and the severity of both precancerous and cancerous lesions of the gastric cardia in an Asian population at high risk of GCA. These findings suggest that H. pylori infection may play a role throughout both early- and late-stage development of GCA.

Community-Based Upper Gastrointestinal Cancer Screening in a Randomized Controlled Trial: Baseline Results in a Non-high-incidence Area

A cluster-randomized controlled trial (RCT) was conducted to evaluate to the effectiveness of reducing mortality of upper gastrointestinal cancer (UGC) and feasibility of screening through a questionnaire combined with endoscopy in non-high-incidence urban areas in China. The trial design, recruitment performance, and preliminary results from baseline endoscopy are reported. Seventy-five communities in two urban cities with a non-high-incidence of UGC were randomized to a screening endoscopy arm (n = 38) or a control arm (n = 37). In the screening arm, individuals at high risk of UGC underwent endoscopic screening. The primary outcome was the UGC mortality, and secondary outcomes included the UGC detection rate, incidence rate, survival rate, and clinical stage at the time of diagnosis. A total of 10,416 and 9,565 individuals were recruited into the screening and control arms, respectively. The participation rate was 74.3%. In the screening arm, 5,242 individuals (50.3%) were estimated to be high-risk. Among them, 2,388 (45.6%) underwent endoscopic screening. Age and household income were associated with undergoing endoscopy. Three early esophageal cancer (0.13%), one gastric cancer (0.04%), 29 precancerous esophageal lesions (1.21%), and 53 precancerous gastric lesions (2.22%) were detected. Age, sex, a family history of cancer, intake of meat-egg-milk frequently, superficial gastritis, and clinical symptoms of gastric cancer were associated with the presence of precancerous lesions. The detection rate was low using endoscopic screening in non-high-incidence area given the relatively low compliance rate. These findings provide a reference for designing effective community-based UGC screening strategies in non-high-incidence urban areas.

Systematic Review with Meta-analysis: Association of Helicobacter pylori Infection with Esophageal Cancer

Background

Helicobacter pylori is an important carcinogenic factor in gastric cancer. Studies have shown that Helicobacter pylori infection is inversely associated with certain diseases such as esophageal cancer and whose infection appears to have a “protective effect.” At present, the relationship between Helicobacter pylori infection and esophageal cancer remains controversial. This study was designed to investigate the relationship between Helicobacter pylori infection and the risk of esophageal cancer in different regions and ethnicities.

Methods

Systematic search of the articles on the relationship between Helicobacter pylori infection and esophageal cancer from the database with the duration time up to December 2018. This systematic review was performed under the MOOSE guidelines.

Results

This meta-analysis included 35 studies with 345,886 patients enrolled. There was no significant correlation between Helicobacter pylori infection and esophageal squamous cell carcinoma in the general population (OR: 0.84; 95% CI: 0.64-1.09/OR: 0.74; 95% CI: 0.54-0.97). However, a significant correlation was found in the Middle East (OR: 0.34; 95% CI: 0.22-0.52/95% CI: 0.26-0.44). There was no significant difference in the prevalence of Helicobacter pylori between the case group and the control group in esophageal adenocarcinoma (8.87% vs. 9.67%). The pooled OR was 0.55 (95% CI: 0.43-0.70) or 0.23 (95% CI: 0.15-0.36). When grouped by match or not, the pooled OR of the nonmatching group and the matching group was 0.48/0.21 (95% CI: 0.36-0.65/95% CI: 0.13-0.36) and 0.73/0.71 (95% CI: 0.57-0.92/95% CI: 0.60-0.84), respectively.

Conclusion

In the general populations, no significant association was found between Helicobacter pylori infection and the risk of esophageal squamous cell carcinoma. However, lower risk was found in the Middle East. Helicobacter pylori infection may reduce the risk of esophageal adenocarcinoma, but such “protection effect” may be overestimated.

Smoking, Helicobacter Pylori Serology, and Gastric Cancer Risk in Prospective Studies from China, Japan, and Korea

Smoking is an established risk factor for gastric cancer development. In this study, we aimed to assess prospectively the association of smoking with gastric cancer risk in 1,446 non-cardia gastric cancer cases and 1,796 controls from China, Japan, and Korea with consideration of Helicobacter pylori infection as a potential effect modifier. Applying logistic regression models stratified by study and adjusted for age and sex we found that current, but not former, smoking was significantly associated with gastric cancer risk [OR = 1.33; 95% confidence interval (CI), 1.07-1.65]. However, the association was significant only in H. pylori sero-positive individuals determined by 3 different sero-markers: overall sero-positivity, sero-positivity to the onco-protein CagA, and sero-positivity to the gastric cancer associated sero-marker HP0305 and HP1564. Specifically, a significant interaction was found when stratifying by HP0305/HP1564 (P _interaction = 0.01) with a 46% increased risk of gastric cancer among HP0305/HP1564 sero-positive current smokers (95% CI, 1.10-1.93) as opposed to no increased gastric cancer risk among HP0305/HP1564 sero-negative current smokers (OR = 0.93; 95% CI, 0.65-1.33). We confirmed that current smoking is associated with an increased gastric cancer risk, however, only among individuals that are simultaneously sero-positive for the leading causal factor for gastric cancer, H. pylori.

Are Helicobacter pylori highly cytotoxic genotypes and cardia gastric adenocarcinoma linked? Lessons from Iran

BACKGROUND

Although the most extensive studies revealed the role of H. pylori VacA and CagA toxins in the development of gastric adenocarcinoma, the magnitude of this association and the correlations of vacA mosaicism and cagA status with cardia gastric adenocarcinoma (CGA) still remain controversial.

OBJECTIVE

We aimed to examine the linkage of H. pylori highly cytotoxic genotypes to CGA in Iranian populations as a model.

METHODS

A total of 601 Iranian patients were enrolled. Biopsies were cultured, genotyped, and anatomically and histologically classified.

RESULTS

The vacA c1 genotype, but not cagA status, showed a strong association with the risk of both CGA and non-cardia adenocarcinoma (NCGA), whether the controls were non-tumors, as those with either non-atrophic gastritis or peptic ulcerations, (the OR (95%CI) was 14.11 (4.91-40.52) and 9.59 (4.06-22.65), respectively) or those with NAG (the OR (95%CI) was 10.71 (3.49-32.82) and 8.11 (3.26-20.16), respectively). The vacA c1/cagA+ genotype was significantly associated with an increased risk of NCGA, whether the controls were non-tumors or those with NAG; the adjusted risk was 4.706 (1.41-15.67) and 4.85 (1.42-16.51), respectively.

CONCLUSIONS

The H. pylori vacA c1 genotype, but not cagA status, might be the first important bacterial biomarker for predicting the cardia adenocarcinoma risk in male patients aged ⩾ 55 in Iran.

Epidemiology of Helicobacter pylori and CagA-Positive Infections and Global Variations in Gastric Cancer

Gastric cancer is a major health burden and is the fifth most common malignancy and the third most common cause of death from cancer worldwide. Development of gastric cancer involves several aspects, including host genetics, environmental factors, and Helicobacter pylori infection. There is increasing evidence from epidemiological studies of the association of H. pylori infection and specific virulence factors with gastric cancer. Studies in animal models indicate H. pylori is a primary factor in the development of gastric cancer. One major virulence factor in H. pylori is the cytotoxin-associated gene A (cagA), which encodes the CagA protein in the cag pathogenicity island (cag PAI). Meta-analysis of studies investigating CagA seropositivity irrespective of H. pylori status identified that CagA seropositivity increases the risk of gastric cancer (OR = 2.87, 95% CI: 1.95⁻4.22) relative to the risk of H. pylori infection alone (OR = 2.31, 95% CI: 1.58⁻3.39). Eradicating H. pylori is a strategy for reducing gastric cancer incidence. A meta-analysis of six randomised controlled trials (RCTs) suggests that searching for and eradicating H. pylori infection reduces the subsequent incidence of gastric cancer with a pooled relative risk of 0.66 (95% CI: 0.46⁻0.95). The introduction in regions of high gastric cancer incidence of population-based H. pylori screening and treatment programmes, with a scientifically valid assessment of programme processes, feasibility, effectiveness and possible adverse consequences, would impact the incidence of H. pylori-induced gastric cancer. Given the recent molecular understanding of the oncogenic role of CagA, targeting H. pylori screening and treatment programmes in populations with a high prevalence of H. pylori CagA-positive strains, particularly the more oncogenic East Asian H. pylori CagA strains, may be worth further investigation to optimise the benefits of such strategies.

Influence of Helicobacter pylori virulence factors CagA and VacA on pathogenesis of gastrointestinal disorders

Helicobacter Pylori (H. pylori) is a gram-negative bacteria infecting numerous people all over the world. It has been established that H. pylori play an important role in pathogenesis of gastritis, peptic ulcer and gastric cancer. Pathogenic features of this bacterium are mainly attributes to the existence of pathogenic islands (PAI) genes. The most known genes in these islands are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin gene (VacA). Most studies demonstrated various frequency of CagA and VacA in patient with peptic ulcer or gastritis in different countries. This variation in CagA and VacA frequency may be due to the capability of this bacterium to be genetically versatile and can alter the expression of these genes with geographic diversity. Although H. pylori infection is not usually associated with any clinical symptoms, but sometimes leads to inflammation in gastrointestinal system and resulted in peptic ulcer and gastric cancer. In this regard, this review will illustrate the importance of Helicobacter pylori in pathogenesis of gastrointestinal disorders with focusing on CagA and VacA virulence factors.

Smoking Status and Gastric Cancer Risk: An Updated Meta-Analysis of Case-Control Studies Published in the past Ten Years

Background

A meta-analysis of published studies was performed in order to clarify the risk of gastric cancer associated with cigarette smoking status.

Methods

Eligible studies were all the case-control studies investigating an association between smoking status and gastric cancer published from January 1, 1997, until June 30, 2006. In order to evaluate the quality of the published data, a qualitative scoring of papers was applied. The principal outcome measure was the odds ratio for the risk of gastric cancer associated with the smoking status using a random effects model. Cigarette smoking status was assessed in two ways: ever (current and ex) versus never smokers; current versus never smokers.

Results

We found a statistically significant result for the association between ever smoking status and gastric cancer risk (OR = 1.48; 95% CI, 1.28–1.71), considering 14,442 cases and 73,918 controls. Moreover, we found an odds ratio of 1.69 for current smoker status in comparison to never smokers (95% CI, 1.35–2.11). Considering only high quality studies, the odds ratio increased by 43% for gastric cancer risk in ever smokers (OR = 1.43; 95% CI, 1.24–1.66; Q = 378.60, P <0.00001; I2 = 90%) and by 57% in current smokers (OR = 1.57; 95% CI, 1.24–2.01). We also considered separately Caucasians and Asian studies, finding for ever smokers an odds ratio of 1.46 (95% CI, 1.25–1.70; Q = 125.68, P <0.00001; I2 = 82.5%) and of 1.47 (95% CI, 1.13–1.91; Q = 366.77, P <0.00001; I2 = 94%), respectively.

Conclusions

From the results of this quantitative meta-analysis, it appears that cigarette smoking has to be considered an important risk factor. The use of qualitative scoring decreases the magnitude of the relationship both for ever and current smoker exposure by 5–12%. Future studies on this topic need to clarify the biological interaction between environmental factors (such as cigarette smoking) and different polymorphisms on gastric cancer.

Helicobacter pylori infection and esophageal adenocarcinoma: a review and a personal view

Esophageal adenocarcinoma (EAC) is etiologically associated with gastroesophageal reflux disease (GERD). There is evidence to support the sequence GERD, Barrett's esophagus (BE), dysplasia, and finally EAC, with Helicobacter pylori (H. pylori) being implicated in each step to EAC. On the other side of this relation stands the hypothesis of the protective role of H. pylori against EAC. Based on this controversy, our aim was to review the literature, specifically original clinical studies and meta-analyses linking H. pylori infection with EAC, but also to provide our personal and others' relative views on this topic. From a total of 827 articles retrieved, 10 original clinical studies and 6 meta-analyses met the inclusion criteria. Original studies provided inconclusive data on an inverse or a neutral association between H. pylori infection and EAC, whereas meta-analyses of observational studies favor an inverse association. Despite these data, we consider that the positive association between H. pylori infection and GERD or BE, but not EAC, is seemingly a paradox. Likewise, the oncogenic effect of H. pylori infection on gastric and colon cancer, but not on EAC, also seems to be a paradox. In this regard, well-designed prospective cohort studies with a powered sample size are required, in which potential confounders should be taken into consideration since their design.

H. pylori infection and gastric cancer in Bangladesh: a case-control study

Background:

Like that of other Asian countries gastric cancer (GC) is also a leading cancer in Bangladesh and also a cause for cancer-related mortality. Infection with Helicobacter pylori (H. pylori) is the strongest recognized risk factor for gastric adenocarcinoma. The infection is also prevalent in common people. This case-control study was carried out to find an association between GC and H. pylori infection in the community.

Materials and Methods:

To evaluate association of H. pylori and carcinoma of stomach this study was conducted at National Institute of Cancer Research & Hospital, Dhaka from January 2013 to December 2014. H. pylori status was determined serologically by using H. pylori kit in the department of Biochemistry laboratory of Bangabandhu Sheikh Mujib Medical University. In total, 114 patients with GC and 520 patients not having GC were studied as controls. Logistic regression method was used to calculate the odds ratio.

Results:

Significantly more patients in the case group (86.8%) were found to be seropositive for H. pylori antigen in contrast to the control group (67.5%). All of the cases in the present study were in advanced stage. No significant association between H. pylori seropositivity and tumor location was found. It was noted that undifferentiated gastric carcinoma had slightly more association with H. pylori infection. Younger H. pylori–infected patients had been found to be at higher relative risk for GC than older patients.

Conclusion:

As there is a strong association found between GC and H. pylori infection special emphasis to eradicate H. pylori infection might reduce the incidence of this dreadly disease.

Autophagy impairment by Helicobacter pylori-induced methylation silencing of MAP1LC3Av1 promotes gastric carcinogenesis

Helicobacter pylori (H. pylori) infection induces methylation silencing of tumor suppressor genes causing gastric carcinogenesis. Impairment of autophagy induces DNA damage leading to genetic instability and carcinogenesis. We aimed to identify whether H. pylori infection induced methylation silencing of host autophagy-related (Atg) genes, impairing autophagy and enhancing gastric carcinogenesis. Gastric mucosae were obtained from 41 gastric cancer patients and 11 healthy volunteers (8 H. pylori-uninfected and 3 H. pylori-infected). Methylation status of Atg genes was analyzed by a methylation microarray and quantitative methylation-specific PCR (qMSP); mRNA expression was assessed by quantitative reverse transcription PCR (qRT-PCR). Cell proliferation, migration and invasion were assessed in normal rat gastric epithelial cells. Gene knock-down was performed by siRNA. Autophagy was assessed by western blotting. Of 34 Atg genes, MAP1LC3A variant 1 (MAP1LC3Av1) and ULK2 were identified by methylation microarray analysis as exhibiting specific methylation in H. pylori-infected mucosae and gastric cancer tissues. Methylation silencing of MAP1LC3Av1 was confirmed by qMSP, qRT-PCR and de-methylation treatment in two gastric cancer cell lines. Knock-down of map1lc3a, the rat homolog of the human MAP1LC3Av1, inhibited autophagy response and increased cell proliferation, migration and invasion in normal rat gastric epithelial cells, despite the presence of map1lc3b, the rat homolog of the human MAP1LC3B gene important for autophagy. Furthermore, MAP1LC3Av1 was methylation-silenced in 23.3% of gastric cancerous mucosae and 40% of non-cancerous mucosae with H. pylori infection. MAP1LC3Av1 is essential for autophagy and H. pylori-induced methylation silencing of MAP1LC3Av1 may impair autophagy, facilitating gastric carcinogenesis.

H. pylori infection is related to mitochondrial microsatellite instability in gastric carcinogenesis

BACHGROUND

To assess the correlation of H. pylori infection with mitochondrial microsatellite instability (mtMSI) and IL-8 in gastric carcinogenesis.

METHODS

H. pylori infection was evaluated through histology and a urease breath test; mtMSI was measured using PCR-single strand conformation polymorphism (PCR-SSCP); IL-8 was analyzed with ELISA methods.

RESULTS

The detection rate of mtMSI was significantly higher in specimens with H. pylori infection than in those without H. pylori infection (P < 0.05). The levels of IL-8 were significantly higher in specimens with mtMSI than in those without mtMSI (P < 0.01).An association of mtMSI with the intestinal histological type was found (P < 0.05). Increased IL-8 levels induced by H. pylori were related to the invasion, lymphnode spreading and clinical stage of gastric cancer (P < 0.05).

CONCLUSIONS

H. pylori infection is related to mitochondrial microsatellite instability in the early steps of gastric cancer development. IL-8 may play a role in the development of mtMSI induced by H. pylori. Our results support a role for mtMSI in different mechanisms of gastric carcinogenesis.

Tag SNPs in long non-coding RNA H19 contribute to susceptibility to gastric cancer in the Chinese Han population

Long non-coding RNA (lncRNA) H19 is involved in tumor development, progression, and metastasis. This case-control study assessed the association between H19 genetic variants and susceptibility to gastric cancer (GC) in a Chinese Han population. We genotyped four lncRNA H19 single nucleotide polymorphisms (SNPs) (rs217727 C > T, rs2839698 C > T, rs3741216 A > T, rs3741219 T > C) in 500 GC patients and 500 healthy controls. Carriers of variant rs217727T and rs2839698T alleles showed increased GC risk (P = 0.008 and 0.011, respectively). Compared with the common genotype, CT + TT rs217727 and CT + TT rs2839698 genotypes were associated with significantly increased GC risk (P = 0.040, adjusted odds ratio [OR] = 1.32, 95% confidence interval [CI] = 1.01-1.71; P = 0.033, adjusted OR = 1.31, 95% CI = 1.02-1.69, respectively). Further stratified analyses revealed that the association between GC risk and variant genotypes of rs217727 was more profound in younger individuals (≤59 years) and non-smokers, while the association between risk and the rare rs2839698 genotype persisted in men and rural subjects. rs2839698 CT and TT genotypes were also associated with higher serum H19 mRNA levels compared with the CC genotype. These findings suggest that lncRNA H19 SNPs may contribute to susceptibility to GC.

Proteomics-Based Identification and Analysis of Proteins Associated with Helicobacter pylori in Gastric Cancer

Helicobacter pylori (H. pylori) is a spiral-shaped Gram-negative bacterium that causes the most common chronic infection in the human stomach. Approximately 1%-3% of infected individuals develop gastric cancer. However, the mechanisms by which H. pylori induces gastric cancer are not completely understood. The available evidence indicates a strong link between the virulence factor of H. pylori, cytotoxin-associated gene A (CagA), and gastric cancer. To further characterize H. pylori virulence, we established three cell lines by infecting the gastric cancer cell lines SGC-7901 and AGS with cagA⁺H. pylori and transfecting SGC-7901 with a vector carrying the full-length cagA gene. We detected 135 differently expressed proteins from the three cell lines using proteome technology, and 10 differential proteins common to the three cell lines were selected and identified by LC-MS/MS as well as verified by western blot: β-actin, L-lactate dehydrogenase (LDH), dihydrolipoamide dehydrogenase (DLD), pre-mRNA-processing factor 19 homolog (PRPF19), ATP synthase, calmodulin (CaM), p64 CLCP, Ran-specific GTPase-activating protein (RanGAP), P43 and calreticulin. Detection of the expression of these proteins and genes encoding these proteins in human gastric cancer tissues by real-time PCR (RT-qPCR) and western blot revealed that the expression of β-ACTIN, LDH, DLD, PRPF19 and CaM genes were up-regulated and RanGAP was down-regulated in gastric cancer tissues and/or metastatic lymph nodes compared to peri-cancerous tissues. High gene expression was observed for H. pylori infection in gastric cancer tissues. Furthermore, the LDH, DLD and CaM genes were demethylated at the promoter -2325, -1885 and -276 sites, respectively, and the RanGAP gene was highly methylated at the promoter -570 and -170 sites in H. pylori-infected and cagA-overexpressing cells. These results provide new insights into the molecular pathogenesis and treatment targets for gastric cancer with H. pylori infection.

Helicobacter pylori eradication for the prevention of gastric neoplasia

BACKGROUND

Gastric cancer is the third most common cause of cancer death worldwide. Individuals infected with Helicobacter pylori have a higher likelihood of developing gastric cancer than individuals who are not infected. Eradication of H. pylori in healthy asymptomatic individuals in the general population may reduce the incidence of gastric cancer, but the magnitude of this effect is unclear.

OBJECTIVES

To assess the effectiveness of eradication of H. pylori in healthy asymptomatic individuals in the general population in reducing the incidence of gastric cancer.

SEARCH METHODS

We identified trials by searching the Cochrane Central Register of Controlled Trials (CENTRAL; 2013, Issue 11), MEDLINE (1946 to December 2013), and EMBASE (1974 to December 2013). We handsearched reference lists from trials selected by electronic searching to identify further relevant trials. We handsearched published abstracts from conference proceedings from the United European Gastroenterology Week (published in Gut) and Digestive Disease Week (published in Gastroenterology) between 2001 and 2013. We contacted members of the Cochrane Upper Gastrointestinal and Pancreatic Diseases Review Group and experts in the field and asked them to provide details of outstanding clinical trials and any relevant unpublished materials.

SELECTION CRITERIA

We analysed randomised controlled trials comparing at least one week of H. pylori therapy with placebo or no treatment in preventing subsequent development of gastric cancer in otherwise healthy and asymptomatic H. pylori-positive adults. Trials had to follow up participants for at least two years and needed to have at least two participants with gastric cancer as an outcome. We defined gastric cancer as any gastric adenocarcinoma, including intestinal (differentiated) or diffuse (undifferentiated) type, with or without specified histology.

DATA COLLECTION AND ANALYSIS

We collected data on incidence of gastric cancer, incidence of oesophageal cancer, deaths from gastric cancer, deaths from any cause, and adverse effects arising due to therapy.

MAIN RESULTS

Six trials met all our eligibility criteria and provided extractable data. Three trials were at low risk of bias, one trial was at unclear risk, and two trials were at high risk of bias. Five trials were conducted in Asian populations. In preventing development of subsequent gastric cancer, H. pylori eradication therapy was superior to placebo or no treatment (6 trials, 6497 participants, risk ratio (RR) of developing subsequent gastric cancer 0.66; 95% confidence interval (CI) 0.46 to 0.95; moderate-quality evidence). Only one trial reported effect of eradication of H. pylori on development of subsequent oesophageal cancer (2 (0.2%) among 817 participants assigned to eradication therapy, compared with 1 (0.1%) of 813 participants allocated to placebo; RR 1.99; 95% CI 0.18 to 21.91). The effect of H. pylori eradication on preventing death from gastric cancer compared with placebo or no treatment was uncertain due to wide confidence intervals (3 trials, 4475 participants, RR 0.67; 95% CI 0.40 to 1.11; moderate-quality evidence). There was no evidence of an effect on all-cause mortality (4 trials, 5253 participants, RR 1.09; 95% CI 0.86 to 1.38; moderate-quality evidence). Adverse events data were poorly reported.

AUTHORS' CONCLUSIONS

We found limited, moderate-quality evidence that searching for and eradicating H. pylori reduces the incidence of gastric cancer in healthy asymptomatic infected Asian individuals, but we cannot necessarily extrapolate this data to other populations.

The Influence of the Gut Microbiome on Obesity, Metabolic Syndrome and Gastrointestinal Disease

There is a fine balance in the mutual relationship between the intestinal microbiota and its mammalian host. It is thought that disruptions in this fine balance contribute/account for the pathogenesis of many diseases. Recently, the significance of the relationship between gut microbiota and its mammalian host in the pathogenesis of obesity and the metabolic syndrome has been demonstrated. Emerging data has linked intestinal dysbiosis to several gastrointestinal diseases including inflammatory bowel disease, irritable bowel syndrome, nonalcoholic fatty liver disease, and gastrointestinal malignancy. This article is intended to review the role of gut microbiota maintenance/alterations of gut microbiota as a significant factor as a significant factor discriminating between health and common diseases. Based on current available data, the role of microbial manipulation in disease management remains to be further defined and a focus for further clinical investigation.

Epidemiology of Barrett's Esophagus and Esophageal Adenocarcinoma

Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma (EAC), a disease with increasing burden in the Western world, especially in white men. Risk factors for BE include obesity, tobacco smoking, and gastroesophageal reflux disease (GERD). EAC is the most common form of esophageal cancer in the United States. Risk factors include GERD, tobacco smoking, and obesity, whereas nonsteroidal antiinflammatory drugs and statins may be protective. Factors predicting progression from nondysplastic BE to EAC include dysplastic changes on esophageal histology and length of the involved BE segment. Biomarkers have shown promise, but none are approved for clinical use.

Chemoprevention in Barrett's oesophagus

Increasing incidence of oesophageal adenocarcinoma along with poor survival entails novel preventive strategies. Agents that target pro-oncogenic pathways in Barrett's mucosa could halt this neoplastic transformation. In this review, we will use epidemiological associations and molecular mechanisms to identify novel chemoprevention targets in Barrett's oesophagus. We will also discuss recent chemoprevention trials.

Risk factors associated with Barrett’s epithelial dysplasia

AIM: To elucidate risk factors associated with dysplasia of short-segment Barrett’s esophagus (BE).

METHODS: A total of 151 BE patients who underwent endoscopic examination from 2004 to 2008 in Aoyama Hospital, Tokyo Women’s Medical University, Japan and whose diagnosis was confirmed from biopsy specimens were enrolled in the study. BE was diagnosed based on endoscopic findings of gastric-appearing mucosa or apparent columnar-lined esophagus proximal to the esophagogastric junction. Dysplasia was classified into three grades - mild, moderate and severe - according to the guidelines of the Vienna Classification System for gastrointestinal epithelial neoplasia. Anthropometric and biochemical data were analyzed to identify risk factors for BE dysplasia. The prevalence of Helicobacter pylori (H. pylori) infection and the expression of p53 by immunohistological staining were also investigated.

RESULTS: Histological examination classified patients into three types: specialized columnar epithelium (SCE) (n = 65); junctional (n = 38); and gastric fundic (n = 48). The incidence of dysplasia or adenocarcinoma from BE of the SCE type was significantly higher than that of the other two types (P < 0.01). The univariate analysis revealed that sex, H. pylori infection, body weight, p53 overexpression, and low diastolic blood pressure (BP) were associated with BE dysplasia. In contrast, body mass index, waist circumference, metabolic syndrome complications, and variables related to glucose or lipid metabolism were not associated with dysplasia. Multivariate logistic analysis showed that overexpression of p53 [odds ratio (OR) = 13.1, P = 0.004], H. pylori infection (OR = 0.19, P = 0.066), and diastolic BP (OR = 0.87, P = 0.021) were independent risk factors for epithelial dysplasia in BE patients with the SCE type.

CONCLUSION: Overexpression of p53 is a risk factor for dysplasia of BE, however, H. pylori infection and diastolic BP inversely associated with BE dysplasia might be protective.

Association of Helicobacter pylori infection with esophageal adenocarcinoma and squamous cell carcinoma: a meta-analysis

To evaluate the relationship of Helicobacter pylori and cytotoxin-associated gene A (CagA) positive strains with esophageal neoplasm, including esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (ESCC), the authors conducted a meta-analysis using a predefined protocol. PubMed, Web of Science, China biology medical literature database, Wanfang, and China National Knowledge Infrastructure were searched for relevant articles from the first available year to April 8, 2013. The fixed or random effect pooled measure was selected based on heterogeneity among studies, which was evaluated using Q test and the I(2) of Higgins and Thompson. Metaregression was used to explore the sources of between-study heterogeneity. Publication bias was analyzed by Begg's funnel plot and Egger's regression test. The association was assessed by odds ratio (OR) with 95% confidence interval (CI). A total of 28 eligible studies were included in the meta-analysis. There was a significant inverse association between H. pylori infection (pooled OR, 0.57; 95% CI, 0.44-0.73) and EAC; CagA-positive H. pylori strains were less likely to be associated with EAC compared with CagA-negative strains (pooled OR, 0.64; 95% CI, 0.52-0.79). However, there was no statistically significant association between H. pylori/CagA-positive H. pylori strains infection and ESCC, and the pooled ORs were 1.16 (95% CI, 0.83-1.60) and 0.97 (95% CI, 0.79-1.19). But significant associations between CagA-positive H. pylori strains infection and ESCC risk were found in the stratified analysis of the study location (Asian and non-Asian), and the summary ORs were 0.74 (95% CI, 0.57-0.97) and 1.41 (95% CI, 1.02-1.94). H. pylori infection and CagA-positive strains are associated with decreased risk of EAC in the overall population. No significant association was found between H. pylori infection/CagA-positive strains and ESCC. But CagA-positive strains might have a positive association with ESCC in non-Asian population and an inverse association in Asian population.

Family history of cancer and gastroesophageal disorders and risk of esophageal and gastric adenocarcinomas: a case-control study

Background

There is a paucity of data on familial risk of developing esophageal adenocarcinoma, gastric cardia adenocarcinoma and distal gastric adenocarcinoma from population-based studies.

Methods

A population-based case–control study of newly diagnosed gastroesophageal adenocarcinoma was conducted in Los Angeles County. This analysis included data of case-patients whom we were able to interview directly (147 patients with esophageal adenocarcinoma, 182 with gastric cardia adenocarcinoma, and 285 with distal gastric adenocarcinoma) and 1,309 control participants. Multivariate polytomous logistic regression was used to estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the three cancer types.

Results

Risk of esophageal adenocarcinoma was positively associated with a family history of prostate cancer (OR = 2.84; 95% CI = 1.50-5.36) and a family history of hiatal hernia (OR = 2.04; 95% CI = 1.12-3.71). Risk of gastric cardia adenocarcinoma was strongly associated with a family history of esophageal cancer (OR = 5.18; 95% CI = 1.23-21.79) and a family history of hiatal hernia (OR = 2.31; 95% CI = 1.37-3.91). Risk of distal gastric adenocarcinoma was positively associated with a family history of gastric cancer (OR = 2.15; 95% CI = 1.18-3.91), particularly early-onset (before age 50) gastric cancer (OR = 2.82; 95% CI = 1.11-7.15).

Conclusions

This study provides evidence that family history of hiatal hernia is a risk factor for esophageal adenocarcinoma and gastric cardia adenocarcinoma and that cancer in specific sites is associated with risk of esophageal adenocarcinoma, gastric cardia adenocarcinoma, and distal gastric adenocarcinoma. It is important to determine the extent to which shared environmental and genetic factors explain these familial associations.

Different histological status of gastritis in superficial adenocarcinoma of the esophagogastric junction

OBJECTIVE

Although many gastric cancers arise in chronic gastritis, the association between adenocarcinoma of the esophagogastric junction and the status of background gastritis remains unclear. We aim to investigate the histological status of gastritis in the background fundic gland mucosa of adenocarcinoma of the esophagogastric junction.

METHODS

The present study included 121 consecutive patients with superficial adenocarcinoma of the esophagogastric junction obtained by surgical and/or endoscopic resection. We re-evaluated the histogenesis of adenocarcinoma of the esophagogastric junction, including the background fundic gland mucosa using the Updated Sydney System. The prevalence of histologic atrophic gastric mucosa with gastritis (positive gastritis), non-atrophic gastric mucosa without gastritis (negative gastritis) and Barrett's adenocarcinoma was examined.

RESULTS

Histologic-positive gastritis was found in 67 (55%) of all patients, in 24 (38%) of 63 Barrett's adenocarcinoma patients and in 43 (74%) of 58 non-Barrett's adenocarcinoma patients (P < 0.01). A higher female ratio in non-Barrett's adenocarcinoma with gastritis patients `and younger age in non-Barrett's adenocarcinoma without gastritis patients were shown. There were no differences in clinicopathological features related to the gastritis status in Barrett's adenocarcinoma patients. Reflux esophagitis was observed in most (81%) of all patients, and 32 (74%) of the non-Barrett's adenocarcinoma with gastritis patients. In the 67 positive gastritis patients, the mean Updated Sydney System scores of glandular atrophy and intestinal metaplasia were 1.45 and 1.10, respectively, and these scores were higher in the non-Barrett's adenocarcinoma patients than in the Barrett's adenocarcinoma patients.

CONCLUSIONS

This study suggests that about half of the patients with adenocarcinoma of the esophagogastric junction harbor histological gastritis. Adenocarcinoma of the esophagogastric junction is considered to be a heterogeneous entity, including Barrett's esophagus-related, positive gastritis-related, and Barrett's esophagus and gastritis-unrelated adenocarcinoma of the esophagogastric junction.

Helicobacter pylori infection and esophageal cancer risk: an updated meta-analysis

AIM

To clarify the association between Helicobacter pylori (H. pylori) infection and the risk of esophageal carcinoma through a meta-analysis of published data.

METHODS

Studies which reported the association between H. pylori infection and esophageal cancer published up to June 2013 were included. The odds ratios (ORs) and corresponding 95%CIs of H. pylori infection on esophageal cancer with respect to health control groups were evaluated. Data were extracted independently by two investigators and discrepancies were resolved by discussion with a third investigator. The statistical software, STATA (version 12.0), was applied to investigate heterogeneity among individual studies and to summarize the studies. A meta-analysis was performed using a fixed-effect or random-effect method, depending on the absence or presence of significant heterogeneity.

RESULTS

No significant association between H. pylori infection and esophageal squamous cell carcinoma (ESCC) risk was found in the pooled overall population (OR = 0.97, 95%CI: 0.76-1.24). However, significant associations between H. pylori infection and ESCC risk were found in Eastern subjects (OR = 0.66, 95%CI: 0.43-0.89). Similarly, cytotoxin-associated gene-A (CagA) positive strains of infection may decrease the risk of ESCC in Eastern subjects (OR = 0.77, 95%CI: 0.65-0.92), however, these associations were not statistically significant in Western subjects (OR = 1.26, 95%CI: 0.97-1.63). For esophageal adenocarcinoma (EAC) the summary OR for H. pylori infection and CagA positive strains of infection were 0.59 (95%CI: 0.51-0.68) and 0.56 (95%CI: 0.45-0.70), respectively.

CONCLUSION

H. pylori infection is associated with a decreased risk of ESCC in Eastern populations and a decreased risk of EAC in the overall population.

DNMT3A rs36012910 A>G polymorphism and gastric cancer susceptibility in a Chinese population

DNA-methyltransferase (DNMT)-3A plays a crucial role in embryonic development and aberrant DNA methylation in carcinogenesis. Polymorphisms of the DNMT3A gene may influence its enzymatic activity and its contribution to susceptibility to cancer. This study evaluated the association of DNMT3A rs36012910 A>G with susceptibility to gastric cancer (GC) in a Chinese population. Genomic DNA was extracted from samples taken from 340 patients with GC and 251 healthy control subjects. The genotype frequency of DNMT3A rs36012910 A>G in all subjects was detected by polymerase chain reaction-restriction fragment length polymorphism and confirmed by sequencing. Stratification analyses were used to study subgroups by age and gender and to evaluate the association of rs36012910 A>G polymorphism with genetic susceptibility to GC. All patients and control individuals were successfully genotyped for the DNMT3A rs36012910 A>G polymorphism. The frequency of DNMT3A rs36012910 allele G is 3.39 % in healthy individuals and 7.78 % in GC patients, respectively. The rs36012910 AG genotype was significantly more common in the GC group than in the controls, although the rs36012910 GG genotype was only one case in GC patients. Further stratification indicated that AG+GG genotypes were associated with susceptibility to GC in males older than 60, but this polymorphism has no significant association with GC susceptibility in females. Male individuals who carried AG+GG genotypes had a 2.362-fold increased risk of GC compared to those who carried the AA genotype. The rs36012910 allele G was associated with an increased risk of GC compared to the rs36012910 allele A. This is the first report to investigate the distribution and evaluate the association of a rare SNP in DNMT3A with genetic susceptibility to GC. DNMT3A rs36012910 A>G might become a potential biomarker for use in GC prediction, although further studies in larger groups and different populations are needed for confirmation.

Descriptive epidemiology of gastric adenocarcinoma in the state of Texas by ethnicity: Hispanic versus White non-Hispanic

BACKGROUND

We aimed to evaluate the clinicopathological and demographic characteristics of gastric adenocarcinoma in Hispanics and compare these trends with those found in non-Hispanic Whites in Texas.

METHODS

Records of patients with gastric adenocarcinoma found in the Texas Cancer Registry from 1995 to 2006 were reviewed. Four ethnic-geographic groups were formed: Hispanics residing in El Paso County (a county on the Texas-Mexico border), White non-Hispanics in El Paso County, Hispanics from the remaining counties of Texas combined, and White non-Hispanics from the remaining counties of Texas combined. Adjusted prevalence ratios (PRs) for the outcome of late stage at diagnosis were calculated.

RESULTS

Of 9949 patients, 561 patients were El Paso County residents, of whom 83% were Hispanics. Among the four ethnic-geographic groups, the age-adjusted incidence was the highest in Hispanics in El Paso County (15.5 cases/100000). Tumor pathobiology varied by ethnicity. White non-Hispanics were more likely than Hispanics to have a proximal tumor and less likely to have a poorly differentiated or undifferentiated tumor. In El Paso County, patients in each of the eight age groups under 75 years compared to patients aged ≥85 years were significantly more likely to be at late stage (adjusted PRs 1.44-1.71).

CONCLUSION

The incidence of gastric adenocarcinoma is higher in Hispanics than in Whites in both El Paso County and the remaining portion of Texas. Hispanics have a higher grade of gastric adenocarcinoma. The prevalence of late stage at the time of diagnosis is higher in younger patients than in older patients.

Diabetes and risk of esophageal and gastric adenocarcinomas

Diabetes has been consistently associated with an increased risk of liver, pancreas and endometrial cancer and has been implicated as a risk factor for esophageal and gastric cancers, although this association has been less well studied. We sought to determine the role of diabetes in the etiology of esophageal, gastric cardia and distal gastric adenocarcinomas (DGAs). This analysis included patients with esophageal adenocarcinoma (EA) (n = 209), gastric cardia adenocarcinoma (GCA) (n = 257) and DGA (n = 382), and 1,309 control participants from a population-based case-control study conducted in Los Angeles County. The study included non-Hispanic whites, African Americans, Hispanics and Asian Americans. The association of diabetes with the three tumor types was estimated using polytomous logistic regression. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated. Nine percent of control participants and 13% of the case patients reported a history of diabetes. After adjustment for age, gender, race, birthplace, education, cigarette smoking status and body mass index, diabetes was associated with an increased risk of EA (OR, 1.48; 95% CI, 0.94-2.32; p = 0.089) and DGA (OR, 1.47; 95% CI, 1.01-2.15; p = 0.045), but was not associated with risk of GCA (OR, 0.96; 95% CI, 0.59-1.55; p = 0.87). However, the association between diabetes and risk of DGA was statistically significant only among patients for whom we interviewed their next of kin. Our study further investigated the association between diabetes and adenocarcinomas of the esophagus and distal stomach.

Should adenocarcinoma of the esophagogastric junction be classified as esophageal cancer? A comparative analysis according to the seventh AJCC TNM classification

OBJECTIVE

The aim of this study was to evaluate the adequacy of esophageal classification for adenocarcinoma of the esophagogastric junction (AEJ) of the seventh American Joint Committee on Cancer (AJCC) TNM classification.

BACKGROUND

The seventh AJCC TNM classification proposed the new classification for AEJ as a part of esophageal cancer depending on the esophagogastric junction (EGJ) involvement. However, there are still many controversies over the classification system for AEJ.

METHODS

A review of pathologic reports and photographic findings at Seoul National University Hospital from 2003 to 2009 identified 4524 patients with single, primary adenocarcinoma of the EGJ (n = 497) and other regions of the stomach (GC, n = 4027) who underwent an operation with curative intent. We analyzed the clinicopathologic features and postoperative prognosis of AEJ using the Siewert classification and the seventh AJCC TNM classification.

RESULTS

There was no Siewert type I (AEJ I) in this study. The prognosis of AEJ was similar to that of GC. There was no difference in clinicopathologic features between AEJ II and AEJ III. Even though AEJ extending into the EGJ (AEJe) showed more advanced pathologic features than AEJ not extending into the EGJ (AEJg), the prognosis of AEJe and AEJg was not significantly different when stratified by T stage. Compared with the classification of gastric cancer applied for AEJ, esophageal classification for AEJ from the seventh AJCC TNM classification showed a loss of distinctiveness at each TNM stage.

CONCLUSIONS

To evaluate the postoperative prognosis of AEJ within the stomach, AEJ II and AEJ III should be considered a part of gastric cancer irrespective of EGJ involvement.

Identification of genetic modifiers of CagA-induced epithelial disruption in Drosophila

Helicobacter pylori strains containing the CagA protein are associated with high risk of gastric diseases including atrophic gastritis, peptic ulcers, and gastric cancer. CagA is injected into host cells via a Type IV secretion system where it activates growth factor-like signaling, disrupts cell-cell junctions, and perturbs host cell polarity. Using a transgenic Drosophila model, we have shown that CagA expression disrupts the morphogenesis of epithelial tissues such as the adult eye. Here we describe a genetic screen to identify modifiers of CagA-induced eye defects. We determined that reducing the copy number of genes encoding components of signaling pathways known to be targeted by CagA, such as the epidermal growth factor receptor (EGFR), modified the CagA-induced eye phenotypes. In our screen of just over half the Drosophila genome, we discovered 12 genes that either suppressed or enhanced CagA's disruption of the eye epithelium. Included in this list are genes involved in epithelial integrity, intracellular trafficking, and signal transduction. We investigated the mechanism of one suppressor, encoding the epithelial polarity determinant and junction protein Coracle, which is homologous to the mammalian Protein 4.1. We found that loss of a single copy of coracle improved the organization and integrity of larval retinal epithelia expressing CagA, but did not alter CagA's localization to cell junctions. Loss of a single copy of the coracle antagonist crumbs enhanced CagA-associated disruption of the larval retinal epithelium, whereas overexpression of crumbs suppressed this phenotype. Collectively, these results point to new cellular pathways whose disruption by CagA are likely to contribute to H. pylori-associated disease pathology.

High frequency of Helicobacter pylori in the esophageal mucosa of dyspeptic patients and its possible association with histopathological alterations

BACKGROUND

Helicobacter pylori gastric colonization is known to be high in symptomatic subjects. However, only a few reports on the presence of H. pylori in the esophageal mucosa have been published. The aim of this study was to assess the frequency of H. pylori in the esophagus of dyspeptic patients and its association with histopathology.

METHODS

The presence of H. pylori in the gastroesophageal mucosa was detected by fluorescence in situ hybridization (FISH) and PCR analysis of DNA extracted from gastric and esophageal biopsies of 82 symptomatic patients, using genus- and species-specific PCR primers. Alterations in the gastroesophageal mucosa were assessed by conventional histological techniques.

RESULTS

H. pylori in the stomach was detected by PCR and FISH, respectively, in 61% (n=43) and 90% (n=63) of dyspeptic patients, and in the esophagus in 70% (n=44) and 73% (n=46). The prevalence of cagA-positive strains by PCR varied from 50% (n=35) in the gastric mucosa to 65% (n=41) in the esophageal mucosa. By combining the results of both methods, H. pylori was present in the gastroesophageal mucosa in 86% (n=68) of patients. The association of the presence of bacteria, including H. pylori, in the esophageal mucosa with histopathological alterations was statistically significant between microabscesses and bacteria (r=0.656, p<0.0001) and PCR detection and pseudogoblet cells (r=0.25, p<0.047).

CONCLUSIONS

This is the first report of the occurrence of H. pylori in the esophageal mucosa from dyspeptic Venezuelan patients. These results demonstrate the high prevalence of H. pylori in the esophagus, and its presence was correlated with signs of inflammation.

Risk factors for neoplastic progression in Barrett’s esophagus

Barrett’s esophagus (BE) confers a significant increased risk for development of esophageal adenocarcinoma (EAC), with the pathogenesis appearing to progress through a “metaplasia-dysplasia-carcinoma” (MDC) sequence. Many of the genetic insults driving this MDC sequence have recently been characterized, providing targets for candidate biomarkers with potential clinical utility to stratify risk in individual patients. Many clinical risk factors have been investigated, and associations with a variety of genetic, specific gastrointestinal and other modifiable factors have been proposed in the literature. This review summarizes the current understanding of the mechanisms involved in neoplastic progression of BE to EAC and critically appraises the relative roles and contributions of these putative risk factors from the published evidence currently available.

The Human Gastric Pathogen Helicobacter pylori and Its Association with Gastric Cancer and Ulcer Disease

With the momentous discovery in the 1980's that a bacterium, Helicobacter pylori, can cause peptic ulcer disease and gastric cancer, antibiotic therapies and prophylactic measures have been successful, only in part, in reducing the global burden of these diseases. To date, ~700,000 deaths worldwide are still attributable annually to gastric cancer alone. Here, we review H. pylori's contribution to the epidemiology and histopathology of both gastric cancer and peptic ulcer disease. Furthermore, we examine the host-pathogen relationship and H. pylori biology in context of these diseases, focusing on strain differences, virulence factors (CagA and VacA), immune activation and the challenges posed by resistance to existing therapies. We consider also the important role of host-genetic variants, for example, in inflammatory response genes, in determining infection outcome and the role of H. pylori in other pathologies—some accepted, for example, MALT lymphoma, and others more controversial, for example, idiopathic thrombocytic purpura. More recently, intriguing suggestions that H. pylori has protective effects in GERD and autoimmune diseases, such as asthma, have gained momentum. Therefore, we consider the basis for these suggestions and discuss the potential impact for future therapeutic rationales.

Race, African ancestry, and Helicobacter pylori infection in a low-income United States population

BACKGROUND

Gastric cancer incidence in African Americans is twice that of whites, and differing prevalence of Helicobacter pylori strain-specific isolates may help explain the disparity.

METHODS

Serum levels of antibodies to each of 15 H. pylori proteins were assessed using multiplex serology for a sample of 689 African American and white participants from the Southern Community Cohort Study. African and European admixture was estimated using a panel of 276 ancestry genetic markers, with "low," "medium," and "high" categories of African ancestry defined as <85%, 85% to 95%, and ≥95%.

RESULTS

The majority (79%) of our study population were sero-positive for H. pylori. African American race was associated with a two- to sixfold increased odds for sero-positivity to eight H. pylori proteins, including the cancer-associated virulence constituents CagA [odds ratio (OR), 6.4; 95% CI, 4.5-9.1], and VacA (OR, 2.3; 95% CI, 1.5-3.5). Compared to whites, African Americans of low, medium, and high African ancestry had 1.6-, 4.1-, and 5.2-fold increased odds of sero-positivity to H. pylori, primarily related to CagA sero-positive strains, for which increasing African ancestry led to 2.5-, 9.6-, and 13.1-fold increased odds. Among African Americans alone, compared to those of low African ancestry, African Americans of medium and high African ancestry had 2.5- and 3.4-fold increased odds of sero-positivity to H. pylori, and 3.5- and 4.9-fold increased odds of CagA sero-positive H. pylori strains.

CONCLUSIONS

Host genetic variation and/or lifestyle factors associated with African ancestry contribute to the likelihood of infection with H. pylori, particularly its virulent strains, in this low-income U.S. southern population.

IMPACT

Our findings that low-income African Americans of high African ancestry have a particularly high prevalence of antibodies against H. pylori provides a framework for further research into better detection and prevention of gastric cancer in this population.

Ku80 gene G-1401T promoter polymorphism and risk of gastric cancer

AIM: To evaluate the possible relationship between the Ku80 gene polymorphism and the risk of gastric cancer in China.

METHODS: In this hospital-based case-control study of gastric cancer in Jiangsu Province, China, we investigated the association of the Ku80 G-1401T (rs828907) polymorphism with gastric cancer risk. A total of 241 patients with gastric cancer and 273 age- and sex-matched control subjects were genotyped and analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS: The frequencies of genotypes GG, GT and TT were 65.6%, 22.8% and 11.6% in gastric cancer cases, respectively, and 75.8%, 17.6% and 6.6% in controls, respectively. There were significant differences between gastric cancer and control groups in the distribution of their genotypes (P = 0.03) and allelic frequencies (P = 0.002) in the Ku80 promoter G-1401T polymorphism.

CONCLUSION: The T allele of Ku80 G-1401T may be associated with the development of gastric cancer.

Helicobacter pylori infection and gastric cardia cancer: systematic review and meta-analysis

OBJECTIVE

Helicobacter pylori infection is the most important risk factor for gastric cancer, but no association with cardia cancer has been recognized. However, a heterogeneous distribution of etiologically distinct types of cardia cancer may contribute to explain conflicting findings between studies in high- and low-risk settings. We aimed to quantify the association between H. pylori infection and gastric cardia cancer through meta-analysis, and to provide an explanation for the expected heterogeneity of results.

METHODS

We systematically reviewed published studies addressing the association between H. pylori infection and gastric cardia cancer (up to June 2009), and extracted relative risk (RR) estimates for the association with cardia and non-cardia cancers. Summary RR estimates and 95% confidence intervals (95% CI) were computed using random-effects models. Subgroup analyses were conducted, namely according to gastric cancer risk settings.

RESULTS

Thirty-four articles were considered for meta-analysis. For cardia cancer, summary RR was 1.08 (95% CI 0.83-1.40; I (2) = 52.8%), higher in high-risk (RR = 1.98; 95% CI 1.38-2.83; I (2) = 18.4%) than in low-risk settings (RR = 0.78; 95% CI 0.63-0.97; I (2) = 11.6%). For non-cardia cancer, RR estimates were similar in high- (RR = 3.02; 95% CI 1.92-4.74; I (2) = 90.7%) and low-risk settings (RR = 2.56; 95% CI 1.99-3.29; I (2) = 46.6%). These observations were consistent across different inclusion criteria and when accounting for the virulence of the infecting strains.

CONCLUSIONS

In high-risk settings, a positive association between H. pylori infection and gastric cancer was observed both for cardia and non-cardia cancers. The results support the hypothesis of a heterogeneous distribution of etiologically distinct types of cardia cancer.

Epidemiology of adenocarcinoma of the esophagus, gastric cardia, and upper gastric third

The incidence of adenocarcinoma of the esophagus and esophagogastric junction (gastric cardia) has risen rapidly over the past three decades in the United States and northern Europe. This increase had been most dramatic among White males. The majority of these cancers arise from Barrett's esophagus. However, less than 10% of the patients with esophageal adenocarcinoma were known to have Barrett's esophagus before. Current evidence indicates that gastroesophageal reflux and obesity are major risk factors for adenocarcinoma of the esophagus. Abdominal obesity, more prevalent in males, and independent of body mass index, seems to be associated with an increased risk of esophageal adenocarcinoma but not of cardia adenocarcinoma. This observation may explain the high male:female ratio observed in esophageal adenocarcinoma. Tobacco use has also been found as a possible risk factor for adenocarcinoma of the esophagus and gastric cardia. Infection with Helicobacter pylori and the use of nonsteroidal anti-inflammatory drugs might reduce the risk. On the other hand, low intake of fruits, vegetables, and cereal fibers seem to increase the risk of esophageal adenocarcinoma. Currently, there is no evidence that strongly supports any specific strategy to screen a subgroup of the population at risk for adenocarcinoma of the esophagus or esophagogastric junction. Future strategies to decrease obesity and tobacco use might help to reduce the burden of esophageal adenocarcinoma at least partially.

Association of Helicobacter pylori infection with reduced risk for esophageal cancer is independent of environmental and genetic modifiers

BACKGROUND & AIMS

Infection with Helicobacter pylori is associated with reduced risk of esophageal adenocarcinoma (EAC), but it is not clear whether this reduction is modified by genotype, other host characteristics, or environmental factors. Furthermore, little is known about the association between H pylori and adenocarcinomas of the esophagogastric junction (EGJAC) or squamous cell carcinomas (ESCC). We sought to measure the association between H pylori infection and esophageal cancer and identify potential modifiers.

METHODS

In an Australian, population-based, case-control study, we compared the prevalence of H pylori seropositivity and single nucleotide polymorphisms in interleukin (IL)-1B (-31, -511) and tumor necrosis factor (TNF)-alpha (-308, -238) among 260 EAC, 298 EGJAC, and 208 ESCC patients and 1346 controls. To estimate relative risks, we calculated odds ratios (OR) and 95% confidence intervals (CI) using multivariable logistic regression in the entire sample and within strata of phenotypic and genotypic risk factors.

RESULTS

H pylori infection was associated with significantly reduced risks of EAC (OR, 0.45; 95% CI: 0.30-0.67) and EGJAC (OR, 0.41; 95% CI: 0.27-0.60) but not ESCC (OR, 1.04; 95% CI: 0.71-1.50). For each cancer subtype, risks were of similar magnitude across strata of reflux frequency and smoking status. We found no evidence that polymorphisms in IL-1B or TNF-alpha modified the association between H pylori and EAC or EGJAC.

CONCLUSIONS

H pylori infection is inversely associated with risks of EAC and EGJAC (but not ESCC); the reduction in risk is similar across subgroups of potential modifiers.

Barrett esophagus: an update

Many developments have been made in the field of Barrett esophagus that have tremendous clinical implications. There are new definitions of Barrett esophagus that have had an immediate clinical impact on cancer risk and screening. Of interest is the definition by the British Society of Gastroenterology, which does not require the presence of intestinal metaplasia for a diagnosis of Barrett esophagus. Imaging techniques that allow improved visualization of intestinal metaplasia at the cellular level are now being used in clinical practice. New hypotheses elucidating the progression from squamous epithelium to intestinal metaplasia have been proposed. Indeed, the crucial role that transcription factors have in the pathogenesis of Barrett esophagus has been clarified. Improved characterization of the molecular mechanisms underlying Barrett esophagus is an incentive to undertake more basic science research in this field. Such research could also help with the development of chemoprevention strategies for this precancerous condition. This Review discusses the advances in understanding of the pathogenesis, diagnosis and treatment of Barrett esophagus.

The changing face of esophageal cancer

The two main histological esophageal cancer types, adenocarcinoma and squamous cell carcinoma, differ in incidence, geographic distribution, ethnic pattern and etiology. This article focuses on epidemiology with particular reference to geographic and temporal variations in incidence, along with a review of the evidence supporting environmental and genetic factors involved in esophageal carcinogenesis. Squamous cell carcinoma of the esophagus remains predominantly a disease of the developing world. In contrast, esophageal adenocarcinoma is mainly a disease of western developed societies, associated with obesity and gastro-esophageal reflux disease. There has been a dramatic increase in the incidence of adenocarcinoma in developed countries in parallel with migration of both esophageal and gastric adenocarcinomas towards the gastro-esophageal junction.

Helicobacter pylori, nutrition and smoking interactions: their impact in gastric carcinogenesis

Gastric cancer (GC) is the result of a long multi-step and multifactorial process involving possible interactions between Helicobacter pylori infection, environmental exposures and host genetic susceptibility. Interactions between H. pylori infection, tobacco smoking and dietary antioxidants are biologically plausible. Positive interactions between risk factors imply that, in certain subgroups of the population, the risk of GC associated with simultaneous exposure to these factors is higher than that in the rest of the population, and these subgroups have to be the target for preventive measures. Using PubMed, we reviewed all studies published in English up to December 2008 carried out in humans on interactions between H. pylori infection and smoking exposure and between H. pylori infection and dietary factors in gastric carcinogenesis. Although relatively few epidemiological studies have evaluated the effect of the interaction between smoking and H. pylori infection on GC risk, there is a suggestion of a positive interaction between the two factors. In contrast, evidence suggests a negative interaction between dietary antioxidants and H. pylori infections on GC risk. The potential protective effect of dietary antioxidants such as vitamins C and E and beta-carotene seems to be stronger in those infected by H. pylori, even though results are inconsistent. In Asian populations, subjects infected by H. pylori and with high dietary salt intake may have a higher risk of GC than subjects without H. pylori infection and with a low salt intake. The risk of GC associated with red meat, processed meat or endogenous formation of nitrosamines appears to only be observed in subjects infected by H. pylori. More and larger epidemiological studies, mainly prospective studies, are necessary to reach a more definitive conclusion on these interactions.