Gastric mucosa in Mongolian and Japanese patients with gastric cancer and Helicobacter pylori infection

Associations Between Antiparietal Cell Antibody Values and Atrophy in a South and Southeast Asian General Population

GOALS

To investigate the association between atrophy severity and antiparietal cell antibody (APCA) levels in South and Southeast Asia.

BACKGROUND

APCA is an autoantibody that damages gastric parietal cells; autoimmune gastritis (AIG) is a chronic gastric inflammatory disease related to APCA and severe predominant corpus atrophy. Although a positive APCA result is a key clinical diagnostic tool for AIG, its rates vary widely among ethnic groups, and its exact relationship with AIG and predominant corpus atrophy remains unclear.

STUDY

Associations between histopathology-assessed and endoscopy-assessed atrophy, APCA positivity rates, Helicobacter pylori status, and pepsinogen levels were investigated in 1982 symptomatic patients from Vietnam, Thailand, Myanmar, Bangladesh, and Nepal.

RESULTS

Overall, 38.5% of participants were negative for Helicobacter pylori infection, while 57.6% had a current infection. A positive APCA result, defined as a titer >10, was present in 44.0% of participants (95% confidence interval: 41.8%-46.3%, 873/1982). Pathologic atrophy, corpus atrophy, and predominant corpus atrophy were found in 8.7% (169/1982), 5.1% (101/1982), and 4.1% (81/1982) of participants, respectively. Positive APCA rates significantly differed among countries (10.6% to 63.8%, P<0.001). No significant correlation was found between APCA results and the presence or severity of atrophy.

CONCLUSIONS

Although APCA positivity was high among symptomatic patients from South and Southeast Asian countries, few had severe predominant corpus atrophy or positive pepsinogen tests, which suggests a low rate of AIG in this population. Long-term surveillance of APCA-positive individuals is necessary to determine the clinical significance of a positive APCA result without AIG.

Review of foodborne helicobacteriosis

Helicobacteriosis is a common bacterial infection caused by Helicobacter pylori. It affects the stomach and small intestines, leading to inflammation. Bacteria can spread through contaminated food or water. This review explores the role of food in the transmission of H. pylori, drawing on research from the past three decades. People commonly acquire the infection during childhood, often from close family members. Crowded living conditions can also contribute to the spread. This review also discusses various risk factors and highlights the challenges of detecting H. pylori, particularly in its dormant form. Techniques like ribotyping and restriction fragment length polymorphism hold promise for tracing transmission routes, but more long-term studies are needed to account for potential confounding factors.

Study of Helicobacter pylori Isolated from a High-Gastric-Cancer-Risk Population: Unveiling the Comprehensive Analysis of Virulence-Associated Genes including Secretion Systems, and Genome-Wide Association Study

BACKGROUND

The prevalence of gastric cancer in Mongolia, in East Asia, remains the highest in the world. However, most Helicobacter pylori strains in Mongolia have a less virulent Western-type CagA. We aimed to determine how H. pylori genomic variation affected gastric diseases, especially gastric cancer, based on comprehensive genome analysis.

METHODS

We identified a set of 274 virulence-associated genes in H. pylori, including virulence factor and outer membrane protein (OMP) genes, the type four secretion system gene cluster, and 13 well-known virulence gene genotypes in 223 H. pylori strains and their associations with gastric cancer and other gastric diseases. We conducted a genome-wide association study on 158 H. pylori strains (15 gastric cancer and 143 non-gastric cancer strains).

RESULTS

Out of 274 genes, we found 13 genes were variable depending on disease outcome, especially iron regulating OMP genes. H. pylori strains from Mongolia were divided into two main subgroups: subgroup (Sg1) with high risk and Sg2 with low risk for gastric cancer. The general characteristics of Sg1 strains are that they possess more virulence genotype genes. We found nine non-synonymous single nucleotide polymorphisms in seven genes that are linked with gastric cancer strains.

CONCLUSIONS

Highly virulent H. pylori strains may adapt through host-influenced genomic variations, potentially impacting gastric carcinogenesis.

Focusing on Helicobacter pylori infection in the elderly

As a confirmed carcinogen, Helicobacter pylori (H. pylori) is the main cause of inflammatory diseases of the upper digestive tract and even gastric cancer. There is a high prevalence of H. pylori infection among the elderly population, which may cause adverse clinical outcomes. Particularly noteworthy is that guidelines or expert consensus presently available on H. pylori infection overlook the management of the elderly population as a special group. A brief overview of H. pylori in the elderly is as follows. The detection of H. pylori infection can be divided into invasive and non-invasive techniques, and each technique has its advantages and shortcomings. There may be more side effects associated with eradication treatment in elderly individuals, especially for the frail population. Physical conditions and risk-benefit assessments of the elderly should be considered when selecting therapeutic strategies for H. pylori eradication. Unless there are competing factors, elderly patients should receive H. pylori eradication regimens to finally reduce the formation of gastric cancer. In this review, we summarize the latest understanding of H. pylori in the elderly population to provide effective managements and treatment measures.

Differences in the Association Between Modifiable Lifestyle Factors and Gastric Precancerous Lesions Among Mongolians and Han Chinese

Background

There has been a paucity of evidence examining whether preventable behavioral risk factors led to ethnic differences of gastric precancerous lesions (GPL). We aimed to investigate the ethnic disparity of associations between GPL and lifestyle factors in Mongolian and Han Chinese populations.

Methods

The study included participants aged 36-75 years enrolled in the Cancer Screening Program during 2016-2017 in Hohhot and Tongliao City, Inner Mongolia. GPL was defined as the gross cascading events (i.e., gastric ulcer, atrophic gastritis, intestinal metaplasia, and dysplasia) that preceded gastric cancer.

Results

A total of 61638 participants were included, of whom 6863(11·1%) were Mongolians. Alcohol consumption was positively associated with GPL risk in both ethnic groups, but the magnitude was greater in Mongolians (odds ratio (OR) 6·91, 95%CI 5·82-8·28) than in Han Chinese (OR 5·64, 95%CI 5·27-6·04), corresponding to a higher population attributable fraction (PAF) for Mongolians (53·18% vs 43·71%). Besides, the strength of the positive association between physical inactivity and GPL risk was greater among Mongolians (OR 2·02, 95%CI 1·70-2·41; OR 1·09, 95%CI 1·02-1·17 among Han Chinese) with a higher PAF. Smoking was strongly associated with GPL risk in both ethnic groups as well, but the association was more prominent among Han Chinese (OR 5·24 (1·70-2·41) for <10 cigarettes/d, 8·19 (7·48-8·97) for 11-20 cigarettes/d, 7·07 (6·40-7·81) for ≥21 cigarettes/d; the corresponding ORs were 2·96 (2·19-4·00), 6·22 (5·04-7·68), and 7·03 (5·45-9·08) among Mongolians). Lastly, our findings revealed that a significant correlation between insufficient fruits and vegetable consumption and GPL risk was only found among Mongolians (OR 1·27, 95%CI 1·04-1·56).

Conclusions

Our result suggested that high-risk lifestyle factors should be reduced, particularly in Mongolians. Further studies are needed to elucidate the underlying mechanisms and to reduce health disparities in underserved ethnic groups.

Epidemiology Helicobacter pylori infection in children in the Tyva Republic (Russia)

BACKGROUND

Tyva Republic is a small mountainous area at the geographical center of Asia in southern Siberia, with a high incidence of gastric cancer.

AIM

We examined the prevalence of H. pylori and associated risk factors among children in Tyva.

METHODS

Cross-sectional study was conducted among Tuvan children who had upper gastrointestinal symptoms and underwent upper gastroscopy with gastric biopsies. Informed consent was obtained from the parents and assent from the children. Demographic information, ethnicity, parents' education and employment status, and family size were collected. H. pylori infection was diagnosed by histologic examination.

RESULTS

There were 270 children between the ages 7 and 17 years (mean 13.4 ± 2.7); 64% girls; 147e Tuvan and 123 Caucasians. The overall prevalence of H. pylori was high and similar between boys and girls (55 vs. 57%, respectively, p = 0.42). The infection was highest in Tuvan children (67%. vs. 43%, respectively (OR = 2.4; 95%CI = 1.9.4-3), p = 0.05. H. pylori prevalence increased with age from 44% among 7 to 10 years and 64% among those 14 to 17 (OR = 3.0; 95%CI = 1.6-5.8), p = 0.0.005; the pattern was consistent among both ethnic groups. The prevalence of the infection among Caucasian children was inversely correlated with the level of mother's education (44%, vs. 61%) (i.e., for with and without a college education the OR = 2.3; 95%CI = 1.2-3.7), p = 0.02. Neither the total number of children nor adults living in the same household correlated with H. pylori prevalence.

CONCLUSIONS

Strategies to reduce the incidence of gastric cancer in Tyva will need to start in childhood.

Overview of Helicobacter pylori Infection in Indonesia: What Distinguishes It from Countries with High Gastric Cancer Incidence?

Helicobacter pylori infects more than half the human population. However, the prevalence in Indonesia is low, as is the prevalence of gastric cancer. Hence, it could be instructive to compare these prevalence rates and their determining factors with those of countries that have high gastric cancer incidence. Ethnicity and genetic characteristics of H. pylori are important determinants of the H. pylori infection rate in Indonesia. The infection rate is higher in Bataknese, Papuans and Buginese than in Javanese, the predominant ethnic group. Ethnicity is also an important determinant of the genetic characteristics of H. pylori. Analysis of CagA in the EPIYA segment showed that the predominant genotypes in Papuans, Bataknese and Buginese are ABB-, ABDand ABC-type CagA, respectively. Meanwhile, in the countries with high gastric cancer incidence, almost all strains had East Asian type CagA. An antibiotic susceptibility evaluation showed that the standard triple therapy can still be used with caution in several cities. There is a very high rate of resistance to second-line regimens such as levofloxacin and metronidazole. Recent studies have shown that furazolidone, rifabutin and sitafloxacin are potential alternative treatments for antibiotic-resistant H. pylori infection in Indonesia. Rather than focusing on early detection and eradication as in countries with high gastric cancer prevalence, countries with low gastric cancer prevalence should focus on screening the several groups that have a high risk of gastric cancer.

Unraveling the identity of gastric cardiac cancer

The classification of gastric cardiac carcinoma (GCC) is controversial. It is currently grouped with esophageal adenocarcinoma (EAC) as an adenocarcinoma of the gastroesophageal junction (GEJ). Recently, diagnostic criteria for adenocarcinoma in the GEJ were established and GCC was separated from EAC. We viewed published evidence to clarify the GCC entity for better patient management. GCC arises in the cardiac mucosa located from 3 cm below and 2 cm above the GEJ line. Compared with EAC, GCC is more like gastric cancer and affects a higher proportion of female patients, younger patients, those with a lower propensity for reflux disease, a wider histopathologic spectrum, and more complex genomic profiles. Although GCC pathogenesis mechanisms remain unknown, the two-etiology proposal is appealing: in high-risk regions, the Correa pathway with Helicobacter pylori infection, chronic inflammation, low acid and intestinal metaplasia, dysplasia and carcinoma may apply, while in low-risk regions the sequence from reflux toxin-induced mucosal injury and high acid, to intestinal metaplasia, dysplasia and carcinoma may occur. In early GCC a minimal risk of nodal metastasis argues for a role of endoscopic therapy, whereas in advanced GCC, gastric cancer staging rules and treatment strategy appear to be more appropriate than the esophageal cancer staging scheme and therapy for better prognosis stratification and treatment. In this brief review we share recent insights into the epidemiology, histopathology and genetics of GCC and hope that this will stimulate further investigations in order to improve the clinical management of patients with GCC.

High Antibiotic Resistance of Helicobacter pylori and Its Associated Novel Gene Mutations among the Mongolian Population

Mongolia has a high prevalence of Helicobacter pylori infection and the second highest incidence of gastric cancer worldwide. Thus, investigating the prevalence of antibiotic resistance and its underlying genetic mechanism is necessary. We isolated 361 H. pylori strains throughout Mongolia. Agar dilution assays were used to determine the minimum inhibitory concentrations of five antibiotics; amoxicillin, clarithromycin, metronidazole, levofloxacin, and minocycline. The genetic determinants of antibiotic resistance were identified with next-generation sequencing (NGS) and the CLC Genomics Workbench. The resistance to metronidazole, levofloxacin, clarithromycin, amoxicillin, and minocycline was 78.7%, 41.3%, 29.9%, 11.9% and 0.28%, respectively. Multidrug resistance was identified in 51.3% of the isolates investigated which were further delineated into 9 antimicrobial resistance profiles. A number of known antibiotic resistance mutations were identified including rdxA, frxA (missense, frameshift), gyrA (N87K, A88P, D91G/N/Y), 23S rRNA (A2143G), pbp1A (N562Y), and 16S rRNA (A928C). Furthermore, we detected previously unreported mutations in pbp1A (L610*) and the 23S rRNA gene (A1410G, C1707T, A2167G, C2248T, and C2922T). The degree of antibiotic resistance was high, indicating the insufficiency of standard triple therapy in Mongolia.

Gastric mucosal microbiota in a Mongolian population with gastric cancer and precursor conditions

BACKGROUND

Incidence and mortality of gastric cancer (GC) are high in Mongolia despite Helicobacter pylori in the Mongolian population being less virulent.

AIM

To evaluate gastric bacterial microbiota profiles in patients with GC and its precursor histological conditions.

METHODS

We conducted a case-control study among 48 GC and 120 noncancer patients (20 normal gastric mucosa [control], 20 gastritis, 40 with atrophy and 40 intestinal metaplasia [IM]). We performed 16S rRNA gene amplicon sequencing and compared taxonomic and functional prediction profiles based on the diagnosis group and H pylori infection status.

RESULTS

The highest overall bacterial alpha diversity metrics were observed in the control group, followed by the IM and cancer groups. The gastritis and atrophy groups had the least diversity. Lactobacilli and Enterococci were the dominant genus in several cancer patients especially in the absence of H pylori. In addition, Carnobacterium, Glutamicibacter, Paeniglutamicibacter, Fusobacterium and Parvimonas were associated with GC regardless of H pylori infection. Firmicutes were decreased in the gastritis and atrophy groups and increased in the IM and cancer groups. The functional metabolic activity of the Embden-Meyerhof-Parnas pathway and the utilization of sugar, were significantly increased in cancer group compared with the noncancer group.

CONCLUSION

Microbial factors other than H pylori may play a role in Mongolian GC. We identified novel associations between GC and the genera Enterococcus, Lactobacillus, Carnobacterium, Glutamicibacter, Paeniglutamicibacter, Fusobacterium, and Parvimonas.

Incidence of Stomach and Esophageal Cancers in Mongolia: Data from 2009 to 2018

Introduction

Digestive organ cancer is a major public health issue both in Asia and in Mongolia. The most prevalent cancer-related deaths in Mongolia are registered as caused by the stomach, esophagus, and liver. There is a lack of study which investigated the accurate incidence of digestive organ cancer nationwide.

Purpose

We aimed to investigate the incidence of stomach and esophageal cancers in Mongolian population.

Materials and methods

Epidemiologic data were collected between 2009 and 2018 through the oncology departments of hospitals and medical centers in all provinces, soums (the smallest unit of provinces), and major districts of the capital city. We used appropriate statistical methods in SPSS software.

Results

The incidence of esophageal cancer in last 10 years (2009–2018) was 10.09 in 100,000 populations and the highest incidence was registered in Uvs (38.13), Bayan-Ulgii (24.15), and Zavkhan (18.18) provinces, respectively. The incidence of stomach cancer was 20.33 in 100,000 populations and the highest incidences were registered in Uvs (53.01), Khovd (46.02), and Darkhan-Uul (40.50) provinces, respectively.

Conclusion

The incidences of these cancers have increased last 10 years in some provinces. Stomach and esophageal cancers incidence in Mongolia is considerably higher compared to the other Asian countries. The nationwide targeted prevention program is needed.

How to cite this article

Lonjid T, Sambuu T, Tumurbat N, et al. Incidence of Stomach and Esophageal Cancers in Mongolia: Data from 2009 to 2018. Euroasian J Hepato-Gastroenterol 2020;10(1):16–21.

Western-Type Helicobacter pylori CagA are the Most Frequent Type in Mongolian Patients

Helicobacter pylori infection possessing East-Asian-type CagA is associated with carcinogenesis. Mongolia has the highest mortality rate from gastric cancer. Therefore, we evaluated the CagA status in the Mongolian population. High risk and gastric cancer patients were determined using endoscopy and histological examination. H. pylori strains were isolated from different locations in Mongolia. The CagA subtypes (East-Asian-type or Western-type, based on sequencing of Glu-Pro-Ile-Tyr-Ala (EPIYA) segments) and vacA genotypes (s and m regions) were determined using PCR-based sequencing and PCR, respectively. In total, 368 patients were examined (341 gastritis, 10 peptic ulcer, and 17 gastric cancer). Sixty-two (16.8%) strains were cagA-negative and 306 (83.1%) were cagA-positive (293 Western-type, 12 East-Asian-type, and one hybrid type). All cagA-negative strains were isolated from gastritis patients. In the gastritis group, 78.6% (268/341) had Western-type CagA, 2.9% (10/341) had East-Asian-type, and 18.2% (61/341) were cagA-negative. However, all H. pylori from gastric cancer patients possessed Western-type CagA. Histological analyses showed that East-Asian-type CagA was the most virulent strains, followed by Western-type and cagA-negative strains. This finding agreed with the current consensus. CagA-positive strains were the most virulent type. However, the fact that different CagA types can explain the high incidence of gastric cancer might be inapplicable in Mongolia.

Initial Trials With Susceptibility-Based and Empiric Anti-H. pylori Therapies in Mongolia

Background: Mongolia has a high prevalence of Helicobacter pylori infection and gastric cancer. We conducted a prospective, randomized, single-blind study to evaluate the efficacy of common regimens in Mongolia and to obtain specimens for susceptibility testing. Methods: Empiric treatments: 270 patients with confirmed H. pylori infection were randomized to receive 10 days clarithromycin-triple therapy (Clari-TT) (n = 90), modified bismuth quadruple therapy (M-BQT) (n = 90), or sequential therapy (ST) (n = 90). A second group of 46 patients received susceptibility-based Clari-TT. H. pylori was cultured from 131 patients and susceptibility testing was performed. H. pylori eradication was confirmed by stool antigen 4 weeks after the therapy. Results: Intention-to-treat (ITT) analysis cure rates were 71.1% (95% CI = 61.7-80.5%) for Clari-TT, 87.8% (95% CI = 81-94.6%) for M-BQT, 67.8% (95% CI = 58.1-77.5%) for ST vs. 89.1% (95% CI = 86-98.2%) for susceptibility-based Clari-TT. Per-protocol (PP) analysis results for these therapies were 72.7% (63.4-82%), 89.8% (83.5-96.1%), 68.5% (58.8-78.2%), and 97.6% (89.5-99.8%), respectively. Among 131 cultured H. pylori, resistance rates to amoxicillin, clarithromycin, and metronidazole were 8.4, 37.4, and 74%, respectively. Conclusion: In Mongolia, the prevalence of H. pylori resistance is high requiring bismuth quadruple therapy or susceptibility-based therapy to obtain acceptable cure rates.

Evaluation of serum markers for gastric cancer and its precursor diseases among high incidence and mortality rate of gastric cancer area

BACKGROUND

Mongolia has the highest mortality rate of gastric cancer. The early detection of cancer and down-staging screening for high risk patients are essential. Therefore, we aimed to validate serum markers for stratifying patients for further management.

METHODS

Endoscopy and histological examination were performed to determine high risk and gastric cancer patients. Rapid urease test, culture and histological tests were performed to diagnose Helicobacter pylori infection. Serum pepsinogen (PG) I and II and anti-H. pylori IgG were measured by ELISA. Receiver Operating Characteristic analysis was used to extract the best cut-off point.

RESULTS

Totally 752 non-cancer and 50 consecutive gastric cancer patients were involved. The corpus chronic gastritis (72%: 36/50 vs. 56.4%: 427/752), corpus atrophy (42.0%: 21/50 vs. 18.2%: 137/752) and intestinal metaplasia (IM) (64.0%: 32/50 vs. 21.5%: 162/752) were significantly higher in gastric cancer than non-cancer patients, respectively. Therefore, corpus chronic gastritis, corpus atrophy and IM were considered as high risk disease. The best serum marker to predict the high risk status was PGI/II < 3.1 (sensitivity 67.2%, specificity 61%) and PGI/II further reduced to < 2.2 (sensitivity 66%, specificity 65.1%) together with PGI < 28 ng/mL (sensitivity 70%, specificity 70%) were the best prediction for gastric cancer. The best cut-off point to diagnose H. pylori infection was anti-H. pylori IgG > 8 U/mL. Multivariate analysis showed that anti-H. pylori IgG > 8 U/mL and PGI/II < 3.1 increased risk for high risk status and PGI/II < 3.1 remained to increase risk for gastric cancer.

CONCLUSION

The serum diagnosis using PGI/II < 3.1 cut-off value is valuable marker to predict high risk patients for population based massive screening.

The role of integrating conjugative elements in Helicobacter pylori: a review

The genome of Helicobacter pylori contains many putative genes, including a genetic region known as the Integrating Conjugative Elements of H. pylori type four secretion system (ICEHptfs). This genetic regions were originally termed as "plasticity zones/regions" due to the great genetic diversity between the original two H. pylori whole genome sequences. Upon analysis of additional genome sequences, the regions were reported to be extremely common within the genome of H. pylori. Moreover, these regions were also considered conserved rather than genetically plastic and were believed to act as mobile genetic elements transferred via conjugation. Although ICEHptfs(s) are highly conserved, these regions display great allele diversity, especially on ICEHptfs4, with three different subtypes: ICEHptfs4a, 4b, and 4c. ICEHptfs were also reported to contain a novel type 4 secretion system (T4SS) with both epidemiological and in vitro infection model studies highlighting that this novel T4SS functions primarily as a virulence factor. However, there is currently no information regarding the structure, the genes responsible for forming the T4SS, and the interaction between this T4SS and other virulence genes. Unlike the cag pathogenicity island (PAI), which contains CagA, a gene found to be essential for H. pylori virulence, these novel T4SSs have not yet been reported to contain genes that contribute significant effects to the entire system. This notion prompted the hypothesis that these novel T4SSs may have different mechanisms involving cag PAI.

New observations regarding Helicobacter pylori and gastric cancer in Mongolia

BACKGROUND

The incidence and mortality of gastric cancer in Mongolia is among the highest in the world.

METHODS

This was a case-control study in which upper gastrointestinal endoscopy, gastric histology, Helicobacter pylori testing, and risk factor questionnaires were obtained. Histologic subtypes were determined by Lauren's classification.

RESULTS

We enrolled 45 gastric cancer and 108 non-gastric cancer patients. Gastric cancers were located in upper part of stomach in 53.3%, main gastric body in 37.8%, and lower part of stomach in 8.9%. The majority (60%) were diffuse type, followed by intestinal type (36.7%) and indeterminate type (3.3%). H. pylori infections were CagA positive in 100% with cancer vs 81% without cancer (P = .02). The majority of CagA was non-East Asian type (95% with cancer and 94.1% without cancer). Cancer patients had typically related with excessive use of salt, hot beverages, tobacco smoking, and low ingestion of fruits.

CONCLUSION

The characteristic topography of gastric cancer in Mongolia being in the gastric corpus differed from East Asian countries and was more similar to western countries. The risk factors for gastric cancer in Mongolia were similar to other high-risk areas (ie, H. pylori infection, excessive use of salt, tobacco smoking, and low ingestion of fruits).

Prevalence, risk factors, and virulence genes of Helicobacter pylori among dyspeptic patients in two different gastric cancer risk regions of Thailand

Gastric cancer risk is varied among different regions of Thailand. We examined the characteristics of Helicobacter pylori infection in two regions of Thailand. The H. pylori status of 273 dyspeptic patients (136 from the South and 137 from the North; a low and high incidence of gastric cancer region, respectively) was evaluated, and virulence genotypes (cagA, vacA, hrgA and jhp0562-positive/β-(1,3)galT) were determined. The overall H. pylori infection rate was 34.1% (93/273). The prevalence was higher in the North than in the South (50.4% vs. 17.6%, P <0.001) and was significantly higher among individuals with the following characteristics: low income, birthplace in the Northeast or North regions, agricultural employment, or consumption of alcohol or unboiling water. Among these socio-demographic determinants, region was an independent risk factor for H. pylori infection (odds ratio = 6.37). Patients including both H. pylori infected and uninfected cases who lived in the North had significantly more severe histological scores than those in the South. In contrast, among H. pylori-positive cases, patients in the South had significantly more severe histological scores than those in the North. Of the 74 strains cultured, 56.8% carried Western-type cagA, with a higher proportion in the South than in the North (76.2% vs. 49.1%, P = 0.05). In disagreement with the current consensus, patients infected with the Western-type cagA strains had more severe inflammation scores in the antrum than those infected with the East Asian-type cagA strains (P = 0.027). Moreover, Western-type cagA strains induced more severe histological scores in patients from the South than those of either genotype from the North. Other virulence genes had no influence on histological scores. The incidence of gastric cancer in Thailand was different among regions and corresponded to differences in the prevalence of H. pylori infection. More careful follow-up for patients in the South will be required, even if they are infected with H. pylori carrying Western-type cagA.

Helicobacter pylori as an oncogenic pathogen, revisited

Gastric cancer is an inflammation-associated malignancy aetiologically related to infection with the bacterium, Helicobacter pylori, which is considered a necessary but insufficient cause. Unless treated, H. pylori causes life-long acute and chronic gastric inflammation resulting in progressive gastric mucosal damage that may result in gastric cancer. The rate of progression from superficial gastritis, to an atrophic metaplastic mucosa, and ultimately to cancer relates to the virulence of the infecting H. pylori as well as host and environmental factors. H. pylori virulence is a reflection of its propensity to cause severe gastric inflammation. Both mucosal inflammation and H. pylori can cause host genomic instability, including dysregulation of DNA mismatch repair, stimulation of expression of activation-induced cytidine deaminase, abnormal DNA methylation and dysregulation of  micro RNAs, which may result in an accumulation of mutations and loss of normal regulation of cell growth. The difference in cancer risk between the most and least virulent H. pylori strain is only approximately 2-fold. Overall, none of the putative virulence factors identified to date have proved to be disease-specific. The presence, severity, extent and duration of inflammation appear to be the most important factors and current evidence suggests that any host, environmental or bacterial factor that reliably enhances the inflammatory response to the H. pylori infection increases the risk of gastric cancer.

Cancer incidence and cancer control in Mongolia: Results from the National Cancer Registry 2008-12

Mongolia has a high burden from noncommunicable diseases, with cancer now the second leading cause of mortality. Given the paucity of situation analyses from the country, this study reports cancer data based on new cases 2008-12 from the National Cancer Registry of Mongolia covering the entire population (2.87 million). New cancer cases of 21,564 were diagnosed over the 5-year period, with a slight predominance of cases (52%) in men. Liver cancer was the leading cancer site in both sexes (ASRs of 114.7 and 74.6 per 100,000 males and females), and responsible for almost two-fifths of all cancer diagnoses, followed by cancers of stomach, lung and oesophagus in men and cervix, stomach and oesophagus in women. The cumulative risk of incidence for all cancers (27.7% and 20.8% in men and women, respectively) positions Mongolia above China (20.2% and 13.3%), below the United States (34.1% and 28.5%) and similar to Russia (26.1% and 19.1%). These figures shed light on the considerable magnitude of cancer in the country and the large fraction of cancers that can be prevented by lifestyle modifications and vaccine implementation. An expansion of activities of the cancer registry and the continued development of research are necessary steps in support of national cancer control planning in Mongolia.

Different Pathophysiology of Gastritis in East and West? A Western Perspective

Background

Gastritis results from multifactorial gastric mucosal injury. Helicobacter pylori (Hp) is the main cause, and associated diseases have typical underlying patterns of gastritis. Gastric ulcer and gastric cancer (GC) develop from chronic atrophic corpus gastritis (CAG) which therefore represents the most important pattern. GC incidences in East Asia are substantially higher than elsewhere, and this should be also reflected by higher prevalences of CAG and characteristic differences in pathophysiology compared to the West.

Summary

The few available comparative studies of gastritis in Eastern and Western patients are summarized. The main pathogenic factors of gastritis are discussed together with their limitations to explain local differences in disease outcome. Emphasis was put to also include less well-established pathogenic host and environmental factors of possible impact.

Conclusions

CAG is more prevalent in East Asian areas with high GC incidences than the West. Geographic heterogeneity of associated diseases is due to differences in Hp prevalence and virulence as well as modulating host and environmental factors. The following may contribute to the higher burden of CAG in the East: ABD type of CagA with vacA s1 and babA2 alleles of Hp, host Lewis(b) expression in sej/sej nonsecretors, H. heilmannii, low parietal cell mass, high sodium and nitrate intake, preferences in vegetable and fruit consumption, cigarette smoking, air pollution, alcohol. Conversely, green tea, nonfermented soy products and rice may confer protective effects. Hp is on the decline, but also in a world cleared from this bacterium, differences in host genetics will continue to modify gastric disease outcome together with maintained customs as part of cultural diversity.