Gastric Cancer Prevention Strategies Research Articles

Correlation between Metabolic Syndrome and Gastric Cancer: Results of an Evidence-Based Strategy in Oriental Populations.

Metabolic syndrome (MetS) is a cluster of cardiovascular risk factors, including abdominal obesity, hyperglycemia, hypertension, and dyslipidemia. Gastric cancer (GC) is a common malignancy with significant mortality rates. The relationship between MetS and GC risk remains controversial. This systematic review and meta-analysis aimed to evaluate the correlation between MetS and GC. Case-control studies investigating the association between MetS and GC were obtained from various databases, including China National Knowledge Infrastructure (CNKI), SinoMed, Embase, Web of Science, The Cochrane Library, and PubMed. The search was performed from the inception of each database up until September, 2023. Two researchers independently screened the literature, extracted data, and assessed the quality of the included studies. A meta-analysis of the included literature was conducted using Stata 12.0 software. The study protocol is registered in PROSPERO (CRD42023490410). A total of eight studies involving a combined sample size of forty-four thousand eight hundred and seventy participants were included in the meta-analysis. The findings revealed that the risk of developing GC was not significantly associated with body mass index, triglycerides, hypertension, high fasting glucose, or MetS. However, it was found to be positively correlated with high-density lipoprotein cholesterol (OR = 1.69, 95%CI: 1.35-2.12). This meta-analysis suggests that MetS is not significantly associated with an increased risk of GC. The risk of GC increases with the presence of individual MetS components, such as high-density lipoprotein cholesterol. Therefore, GC prevention strategies should include lifestyle modifications and targeted interventions to manage MetS and its components. CRD42023490410 (PROSPERO).

Early Gastric Cancer: Update on Prevention, Diagnosis and Treatment.

Gastric cancer (GC) is a relevant public health issue as its incidence and mortality rates are growing worldwide. There are recognized carcinogen agents, such as obesity, tobacco, meat, alcohol consumption and some dietary protective factors. Strategies of early diagnosis through population-based surveillance programs have been demonstrated to be effective in lowering the morbidity and mortality related to GC in some countries. Indeed, the detection of early lesions is very important in order to offer minimally invasive treatments. Endoscopic resection is the gold standard for lesions with a low risk of lymph node metastasis, whereas surgical mini-invasive approaches can be considered in early lesions when endoscopy is not curative. This review outlines the role of lifestyle and prevention strategies for GC, in order to reduce the patients' risk factors, implement the surveillance of precancerous conditions and, therefore, improve the diagnosis of early lesions. Furthermore, we summarize the available treatments for early gastric cancer.

Effect of Helicobacter Pylori Eradication on Human Gastric Microbiota: A Systematic Review and Meta-Analysis.

Background Helicobacter pylori (H. pylori) infection is a major risk factor for gastric cancer and eradication of H. pylori is recommended as an effective gastric cancer prevention strategy. The infected individuals show microbial dysbiosis of gastric microbiota. In recent years, agrowing number of studies have focused on gastric microbiota changes following H. pylori eradication. In the present study, we aim to evaluate the influence of successful H. pylori eradication on the short-term and long-term alterations of human gastric microbiota using a method of systematic review and meta-analysis.MethodsWe did a systematic search based on three databases (PubMed, EMBASE, and Web of Science) in November 2021. Additional articles were also identified by reviewing references cited in the included papers. Human studies that reported changes in gastric microbiota following successful H. pylori eradication were enrolled. PROSPERO registration number: CRD42021293796.ResultsIn total, nine studies enrolling 546 participants were included. Regarding quadruple therapy, alpha diversity indexes increased within 1 month after eradication; significant differences in gastric microbial community structure between before and after eradication were also seen within 1 month. The trends of the above-mentioned diversity changes persisted with a follow-up of 6 months. The microbial composition altered significantly after eradication and the relative abundance of H. pylori-related taxa decreased. Accordingly, gastric commonly dominant commensals were enriched. Bioinformatic analyses of microbiota functions showed that bacteria reproduction-related pathways were down-regulated and pathways of gastric acid secretion, etc. were up-regulated. For triple therapy, similar trends of alpha diversity and beta diversity changes were observed in the short-term and long-term follow-up. Also, after eradication, H. pylori was not the gastric dominant bacteria and similar changes in gastric microbial composition were found. For gastric microbial interactions, a decrease in microbial interactions was seen after eradication. Additionally, regarding whether successful H. pylori eradication could restore gastric microbiota to uninfected status, the results remain controversial.ConclusionIn conclusion, successful H. pylori eradication could reverse the gastric microbiota dysbiosis and show beneficial effects on gastric microbiota. Our findings may provide new insight for exploring the role of H. pylori and the whole gastric microbiota in gastric carcinogenesis.

Current Evidence for a Paradigm Shift in Gastric Cancer Prevention From Endoscopic Screening to Helicobacter pylori Eradication in Korea.

Gastric cancer is prevalent in Korea and ranked as the third most common cancer in 2019, followed by lung and thyroid cancers. The National Cancer Screening Program (NCSP) for gastric cancer has been implemented in adults aged ≥40 since 1999 and involves endoscopic screening every 2 years. The beneficial effects of the current NCSP on early cancer detection, cost-effectiveness, and mortality reduction are evident. However, the screening program results in a large socioeconomic burden and the consumption of medical resources, as it focuses solely on secondary prevention (early detection) rather than primary prevention of cancer. Helicobacter pylori is defined as a group I carcinogen by the International Agency for Research on Cancer. Hence, its eradication has been suggested as an important primary gastric cancer prevention strategy. Well-designed randomized controlled trials involving high-risk groups (post-endoscopic resection of early gastric cancer and family history of gastric cancer) and long-term follow-up studies in the general population have provided high-quality evidence regarding the effects of H. pylori eradication on gastric cancer prevention. In this review, we discussed the evidences for a possible modification of the current gastric cancer secondary prevention strategy by introducing primary prevention through H. pylori eradication. Areas for future research to optimize primary prevention strategies were also suggested.

Factors influencing participation in preventive interventions for gastric cancer: the results from the GISTAR study.

Search-and-treat strategy for Helicobacter pylori and surveillance of patients with precancerous lesions are recommended to decrease the burden of gastric cancer in high-risk areas. We aimed to evaluate the acceptance of the target population to these strategies. We applied a search-and-treat strategy combined with biomarker screening (pepsinogens I and II, gastrin-17) for atrophic gastritis to healthy individuals aged 40-64 years within the GISTAR Pilot study. Different means of invitation were evaluated - direct telephone calls, letters of invitation via the general practitioners. Participants with altered biomarker results were invited to undergo upper gastrointestinal endoscopy. H.pylori positive individuals were offered eradication therapy. Data on the compliance to the treatment and reasons for noncompliance were collected via telephone. Altogether 3453 participants were enrolled. The attendance of women participants was 1.9 times higher although active invitation strategies were mainly targeting men. The yield for the telephone invitations was higher than for mail-delivered invitations (2.1 calls vs. 7.7 letters required to recruit one study subject). Out of 661 individuals reached with the invitation to undergo upper endoscopy, 520 (78.7%) attended the procedure. Out of 1185 study subjects eligible for eradication, 810 (68.4%) accepted it. Of those having received the medication, 765(94.4%) completed it. The reasons for nonparticipation were the overall misconception of the importance of screening, busy schedule and others. While only the minority of the target population participated in the gastric cancer prevention strategy, relatively high compliance was seen among the participants. The acceptance rate and the identified reasons for refusing to participate in our study indicate that there is a need to raise gastric cancer awareness and its existent preventive strategies within the general population for their successful implementation in the community.

Lifetime incidence risk for gastric cancer in the Helicobacter pylori-infected and uninfected population in Japan: A Monte Carlo simulation study.

Helicobacter pylori (H. pylori) infection is considered the leading cause of gastric cancer. Gastric cancer is currently a common cancer with high incidence and mortality rates, but it is expected that the incidence rate will gradually decrease as the H. pylori infection prevalence decreases in the future. When evaluating the effectiveness of gastric cancer prevention strategies, it is essential to note the differences in long‐term cumulative risks between H. pylori‐infected and uninfected populations, but this has not yet been precisely evaluated. In our study, we aimed to estimate the cumulative incidence risks of developing gastric cancer from birth to 85 years among H. pylori‐infected and uninfected populations by using population‐based cancer registry data and birth year‐specific H. pylori infection prevalence rates. Death from gastric cancer and other causes of death were considered in the estimations of the adjusted cumulative incidence risks stratified by sex and H. pylori infection status. After performing 5000 Monte Carlo simulations with repeated random sampling using observed cancer incidence in selected three prefectures (Fukui, Nagasaki, Yamagata) of prefectural population‐based cancer registry in Japan, the mean adjusted cumulative incidence risk for gastric cancer in the H. pylori‐infected population was 17.0% for males and 7.7% for females and 1.0% for males and 0.5% for females in the uninfected population. These results calculated with Japanese cancer registry data may be useful in considering and evaluating future prevention strategies for gastric cancer in Japan.

Helicobacter pylori Infection in Children and Adolescents.

About one-third of all children worldwide is infected with H. pylori and its prevalence is low in developed and high in developing countries. H. pylori is mainly acquired during childhood and transmission of the bacterium commonly proceeds from person to person, especially among family members. The most frequent transmission route is from the mother to children. Various gastrointestinal and extra-gastrointestinal diseases are reported to be associated with H. pylori in children and adolescents, but the strongest recommendation for testing and treating is introduced only with children and adolescents having peptic ulcer disease. Iron deficiency anemia and chronic immune thrombocytopenic purpura are also considered for testing and treating, but the effectiveness is somewhat controversial. Invasive diagnosis is recommended, whereas none of the available diagnostic tests have 100% accuracy for reliable diagnosis, and therefore at least two or more tests should be performed. Urea breath test is the most reliable among the non-invasive tests. Because the number of antibiotics-resistant H. pylori strains is increasing, it is desirable to conduct a drug susceptibility test before treatment and to select the corresponding regime. H. pylori has been proven to be a major cause of gastric cancer and 'screen-and-treat' strategies are recommended in communities at high risk of gastric cancer. However, the application to children and adolescents is controversial. An effective vaccine is desirable, but not yet available. Screen-and-treat for adolescents has started in a few areas in Japan, where conditions are well established. New prevention strategies for gastric cancer are awaited worldwide.

Accuracy of two plasma antibody tests and faecal antigen test for non-invasive detection of H. pylori in middle-aged Caucasian general population sample

Objective: The aim of the study was to assess the accuracy of two plasma Helicobacter pylori (H. pylori) antibody test-systems and a stool antigen test (SAT) system in a general population sample in Latvia.Materials and methods: Blood and faecal samples were analysed in healthy individuals (40–64 years), referred for upper gastrointestinal endoscopy according to pilot study protocol within a population-based study investigating gastric cancer prevention strategies (GISTAR pilot study). Antibodies to H. pylori were assessed in plasma by latex-agglutination test and enzyme-linked immunosorbent assay (ELISA). H. pylori antigen in faecal samples was detected by a monoclonal enzyme immunoassay-based SAT. Histological assessment of H. pylori based on a modified Giemsa staining method was used as the gold standard. Individuals having received H. pylori eradication within one year prior to enrolment were excluded. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy were calculated. Receiver-operating characteristic curves were designed to estimate the optimal diagnostic cut-off value of tests.Results: The analysis included 779 participants for latex-agglutination test, 1002 for ELISA and 672 individual samples for SAT. The sensitivity, specificity, PPV, NPV and overall accuracy were as follows: latex-agglutination test (86;81;87;80;84%), ELISA (97;72;83;94;86%) and SAT (87;81;87;81;85%), respectively. The optimal diagnostic cut-off value for ELISA test was ≥50.26 g/L.Conclusions: Although the performance of the three tests was comparable to each other, the three test systems showed suboptimal accuracy, with important implications for public health programs based on ‘test-and-treat’ strategy.

Helicobacter pylori Eradication Therapy and Gastric Cancer Prevention

Gastric cancer is the most common cancer in Korea and the fifth most common cancer globally. Helicobacter pylori (H. pylori) infection is considered the main etiologic agent for gastric cancer development. Most regional guidelines for H. pylori treatment recommend treating the organism to prevent gastric cancer in the high-risk group. However, evidence that such a strategy can also be applied to the general population, especially in terms of the preventive effect and safety, has not been adequately presented yet. Although a meta-analysis in the general population suggested effectiveness in decreasing gastric cancer incidence, individual studies should be critically reviewed to evaluate the soundness of the evidence. Recently published, long-term, Korean studies on metachronous gastric cancer prevention ended the controversies from previous short-term studies and confirmed the effectiveness. Currently, further prospective, large, randomized studies are ongoing in the general population and will provide more definitive, high-level evidence on this gastric cancer prevention strategy in the next decade.

Epidemiology of Helicobacter pylori infection in asymptomatic schoolchildren in Bhutan.

Bhutan is a small mountainous country between Tibet and India with relatively homogenous population. According to the World Health Organization, gastric cancer is the most frequent cause of cancer death in Bhutan. This study examined the prevalence of Helicobacter pylori among children in Bhutan with emphasis on water source and living conditions. A cross-sectional sero-epidemiologic study was conducted among schoolchildren who attended public schools in Thimphu, Bhutan. Between 2015 and 2016, blood samples from schoolchildren were collected after obtaining an informed consent from the school management and the children's parents. Demographic information, parents' education, family size living in the same household, and aspects of household environment including type of latrines, boiling drinking water were collected. All serum samples were tested for H.pylori immunoglobulin G (IgG) by commercial ELISA kits. There were 327 children between 4 and 19years of age participated, 44% boys, mean age=13.6±3years. The overall prevalence of H. pylori was 66% with no difference between boys and girls (66 vs 64%, respectively), P=.42. H. pylori prevalence was 75% among both 4-7 and 15-19years and not statically different from that of the 8-10 or 11-14 age groups (59% and 63%, respectively), P=.1. H. pylori prevalence was inversely correlated with the level of mother's education (70% vs 55%) for those without and with a college education, respectively (OR=2.3; 95%CI=0.9-1.7), P=.08. The total number of people living in the same household did not correlate with H. pylori sero-prevalence, but households had less than 3 children had lower prevalence than those with 3 or more children (62% vs 71%, respectively OR=1.7, 95% CI=[1.0-2.6], P=.05). H. pylori infection is prevalent among all age group children in Bhutan. The results suggest that transmission of H. pylori is related to personal care practices that directly correlate with the mothers' education and crowded living condition with children. Our results are important to developing prevention strategies for gastric cancer in Bhutan.

The Clinical Evidence Linking Helicobacter pylori to Gastric Cancer.

Gastric cancer has long been recognized to be accompanied and preceded by chronic gastritis, lasting decades. Arguably, the most important development in our understanding of gastric cancer pathogenesis over the past 50 years has been the realization that, for most cases of gastric cancer, Helicobacter pylori is the cause of the underlying gastritis. Gastritis can promote gastric carcinogenesis, typically via the Correa cascade of atrophic gastritis, intestinal metaplasia, and dysplasia. Nested case-control studies have shown that H pylori infection increases the risk of gastric cancer significantly, both of the intestinal and diffuse subtypes, and that H pylori is responsible for approximately 90% of the world’s burden of noncardia gastric cancer. Based largely on randomized studies in high gastric cancer prevalence regions in East Asia, it appears that primary and tertiary intervention to eradicate H pylori can halve the risk of gastric cancer. Some public health authorities now are starting screening and treatment programs to reduce the burden of gastric cancer in these high-risk areas. However, there is currently much less enthusiasm for initiating similar attempts in the United States. This is partially because gastric cancer is a relatively less frequent cause of cancer in the United States, and in addition there are concerns about theoretical downsides of H pylori eradication, principally because of the consistent inverse relationship noted between H pylori and esophageal adenocarcinoma. Nevertheless, establishing a link between chronic H pylori infection and gastric cancer has led to novel insights into cancer biology, the gastrointestinal microbiome, and on individual and population-based gastric cancer prevention strategies.

Changing epidemiology of Helicobacter pylori in Japan.

Helicobacter pylori (H. Pylori) is known as the most important cause of gastric cancer. The prevalence of H. pylori infection varies widely by geographic area, age, and socioeconomic status. In Japan, H. pylori infection has been highly correlated with the incidence rate of gastric cancer, and a reduction in H. pylori infection is therefore crucial for decreasing the incidence of gastric cancer, especially at the population level. Infection occurs during childhood, commonly before 5years of age. In Japan, where gastric cancer has ranked as the most common cancer by incidence and mortality for the last several decades, the prevalence of H. pylori infection has dramatically declined by birth cohort effect, mainly due to improvements in the general hygiene environment in childhood. Older generations born before around 1950 show a high prevalence of around 80-90%, decreasing with age to reach around 10% or less in those born around the 1990s, and less than 2% for children born after the year 2000. This change will have generational effects on gastric cancer prevention strategies, both primary and secondary. The risk-stratified approach to gastric cancer prevention should be considered in Japan and other countries which have similarly experienced rapid economic development.

Geographical distribution of the incidence of gastric cancer in Bhutan.

To estimate the prevalence of gastric cancer (GC) in a cohort of patients diagnosed with GC and to compare it with patients diagnosed with all other types of gastro-intestinal (GI) cancer during the same period. Between 2008 and 2013, five-year period, the medical records of all GI cancer patients who underwent medical care and confirm diagnosis of cancer were reviewed at the National Referral Hospital, Thimphu which is the only hospital in the country where surgical and cancer diagnosis can be made. Demographic information, type of cancer, and the year of diagnosis were collected. There were a total of 767 GI related cancer records reviewed during the study period of which 354 (46%) patients were diagnosed with GC. There were 413 patients with other GI cancer including; esophagus, colon, liver, rectum, pancreas, gall bladder, cholangio-carcinoma and other GI tract cancers. The GC incidence rate is approximately 0.9/10000 per year (367 cases/5 years per 800000 people). The geographic distribution of GC was the lowest in the south region of Bhutan 0.3/10000 per year compared to the central region 1.4/10000 per year, Eastern region 1.2/10000 per year, and the Western region 1.1/10000 per year. Moreover, GC in the South part was significantly lower than the other GI cancer in the same region (8% vs 15%; OR = 1.8, 95%CI: 1.3-3.1, P = 0.05). Among GC patients, 38% were under the age of 60 years, mean age at diagnosis was 62.3 (± 12.1) years with male-to-female ratio 1:0.5. The mean age among patients with all other type GI cancer was 60 years (± 13.2) and male-to-female ratio of 1:0.7. At time of diagnosis of GC, 342 (93%) were at stage 3 and 4 of and by the year 2013; 80 (23%) GC patients died compared to 31% death among patients with the all other GI cancer (P = 0.08). The incidence rate of GC in Bhutan is twice as high in the United States but is likely an underestimate rate because of unreported and undiagnosed cases in the villages. The high incidence of GC in Bhutan could be attributed to the high prevalence of Helicobacter pylori infection that we previously reported. The lowest incidence of GC in Southern part of the country could be due to the difference in the ethnicity as most of its population is of Indian and Nepal origin. Our current study emphasizes on the importance for developing surveillance and prevention strategies for GC in Bhutan.

Role of Helicobacter pylori infection in gastric carcinogenesis: Current knowledge and future directions.

Helicobacter pylori (H. pylori) plays a role in the pathogenesis of gastric cancer. The outcome of the infection depends on environmental factors and bacterial and host characteristics. Gastric carcinogenesis is a multistep process that is reversible in the early phase of mucosal damage, but the exact point of no return has not been identified. Therefore, two main therapeutic strategies could reduce gastric cancer incidence: (1) eradication of the already present infection; and (2) immunization (prior to or during the course of the infection). The success of a gastric cancer prevention strategy depends on timing because the prevention strategy must be introduced before the point of no return in gastric carcinogenesis. Although the exact point of no return has not been identified, infection should be eradicated before severe atrophy of the gastric mucosa develops. Eradication therapy rates remain suboptimal due to increasing H. pylori resistance to antibiotics and patient noncompliance. Vaccination against H. pylori would reduce the cost of eradication therapies and lower gastric cancer incidence. A vaccine against H. pylori is still a research challenge. An effective vaccine should have an adequate route of delivery, appropriate bacterial antigens and effective and safe adjuvants. Future research should focus on the development of rescue eradication therapy protocols until an efficacious vaccine against the bacterium becomes available.

Helicobacter pylori.

This review focuses on new treatment options for eradicating Helicobacter pylori that have emerged as a result of decreased efficacy of standard triple therapy due to increasing antibiotic resistance. We also report on new data regarding primary and secondary gastric cancer prevention strategies and the potential role of H. pylori as a risk factor for extragastric malignancies. Treatment options have shifted from triple to various quadruple modifications. The length of therapy duration has, in general, been extended from 7 to 10 and 14 days. Nonbismuth-based quadruple therapies prescribed as sequential, concomitant, and hybrid have shown superiority as compared to standard triple therapy in the eradication of clarithromycin-resistant H. pylori. Bismuth-based quadruple therapy appears almost totally independent of antibiotic resistance and maintains high eradication rates. Levofloxacin is an adequate substitute for clarithromycin and is recommended in second-line regimens. However, it should be used prudently as H. pylori has developed resistance to levofloxacin in many regions of the world. Strategies for primary gastric cancer prevention by H. pylori eradication are effective, whereas H. pylori eradication for secondary gastric cancer prevention is uncertain. Very recent data implicate H. pylori as a risk factor for extragastric malignancies. H. pylori therapy should be tailored according to local antibiotic resistance patterns. In many regions of the world, H. pylori is becoming increasingly resistant to clarithromycin, metronidazole, and levofloxacin. Gastric cancer prevention by H. pylori eradication is most effective, if implemented early in the course of infection. New data are provided which indicate H. pylori as risk factor for extragastric malignancies.

Prevention strategies for gastric cancer: a global perspective.

Despite the substantial burden of gastric cancer worldwide, population strategies for primary prevention have not been introduced in any country. Recognizing the causal role of Helicobacter pylori infection, there is increasing interest in population-based programs to eradicate the infection to prevent gastric cancer. Nonetheless, the paucity of available evidence on feasibility and effectiveness has prevented implementation of this approach. There are very few secondary prevention programs based on screening with endoscopy or radiography, notably in the Republic of Korea and Japan, two of the countries with the highest incidence rates of gastric cancer. In Korea, where the organized screening program is in place, survival rate of gastric cancer is as high as 67%. More research is needed to quantify the specific contribution of the screening program to observed declines in mortality rates. Gastric cancer screening is unlikely to be feasible in many Low-Middle Income Countries where the gastric cancer burden is high. Prevention strategies are still under development and the optimal approach may differ depending on local conditions and societal values. The present review gives an overview of the etiology and burden of the disease, and possible prevention strategies for countries and regions confronted with a significant burden of disease.

Epidemiology of Helicobacter pylori in Bhutan: The Role of Environment and Geographic Location

Bhutan is small mountainous country bordering India and China and consists of four geographic regions, west, east, central, and south. The epidemiology of Helicobacter pylori infection and risk factors associated with in Bhutan are not previously studied. The World Health Organization reported the incidence of stomach cancer to be very high in Bhutan. We conducted a cross-sectional study to determine the seroepidemiologic pattern of H.pylori among Bhutanese from the four regions with emphasis on water source and household sanitation. Between June and November 2012, blood samples from patients with complaints of dyspepsia were collected after obtaining an informed consent. Demographic information, occupation, family size living in the same household, consumption of betel nut, and aspects of household environment including type of latrines, source of drinking water were collected. All serum samples were tested for H.pylori immunoglobulin G (IgG) by enzyme-linked immunosorbent assay (ELISA) using MAGIWELL ELISA kit from United Biotech, USA. Two hundred and forty-four patients between 17 and 75years of age participated in the study, of them, 102 were men, and the mean age was 38 (±14.2) years. The overall prevalence of H.pylori among patients was 86% with no difference between men and women (90 vs 83%, respectively, p=.12). The prevalence was almost identical among all age groups: 81% at 17-20, 84% at 20-29, 93% at 30-39, 82% at 40-49, 87% at 50-59, and 82% at ≥60years (p=.51). H.pylori prevalence was lower in the southern region of Bhutan (78%) compared with the central region (97%) (OR=8.6; 95% CI=1.1-55; p=.02), eastern region (91%) (OR=2.7; 95% CI=1.1-7.2, p=.004) or the western region (83%) (OR=1.4, 95% CI=0.8-3.1, p=.07). The prevalence of H.pylori was significantly lower among household with less than 4 persons living in the same household. Source of drinking water, type of occupation, type of latrines, or consumption of betel nut showed no association with H.pylori prevalence. Logistic regression analysis revealed that residing region was the only significant variable. The high prevalence of antibodies to H.pylori among patients and in all groups could contribute to the high incident rate of gastric cancer in Bhutan. Crowded living condition and the residing region contribute to the variation of the prevalence of the infection. The lowest prevalence in southern part of the country could be due to the difference in the ethnicity as most of its population is of Indian and Nepal origin. Further data regarding H.pylori in Bhutan are critical to developing surveillance and prevention strategies for gastric cancer.

Current evidence of effects of Helicobacter pylori eradication on prevention of gastric cancer.

Gastric cancer is the second most common cause of cancer death worldwide and is usually detected at a late stage, except in Korea and Japan where early screening is in effect. Results from animal and epidemiological studies suggest that Helicobacter pylori infection, and subsequent gastritis, promote development of gastric cancer in the infected mucosa. Relatively effective treatment regimens are available to treat H. pylori infection, and in general, mass eradication of the organism is not currently recommended as a gastric cancer prevention strategy. However, regional guidelines vary regarding the indications and recommendations for H. pylori treatment for gastric cancer prevention. In this review, we discuss the results from intervention studies, provide insight regarding current guideline recommendations, and discuss future study directions.

Autoimmune gastritis: histology phenotype and OLGA staging

Among Western populations, the declining incidence of Helicobacter pylori infection coincides with a growing clinical impact of autoimmune gastritis. To describe the histological phenotype of autoimmune gastritis, also to test the prognostic impact of OLGA staging in the autoimmune setting. A single-institutional series (spanning the years 2003-2011) of 562 consecutive patients (M:F ratio: 1:3.7; mean age = 57.6 ± 14.4 years) with serologically confirmed autoimmune gastritis underwent histology review and OLGA staging. Helicobacter pylori infection was ascertained histologically in 44/562 cases (7.8%). Forty six biopsy sets (8.2%) featured OLGA stages III-IV; they included all four cases of incidental epithelial neoplasia (three intraepithelial and one invasive; three of these four cases had concomitant H. pylori infection). There were 230 (40.9%) and 139 (24.7%) cases, respectively, of linear and micro-nodular enterochromaffin-like cell hyperplasia; 19 (3.4%) type I carcinoids were detected. The series included 116 patients who underwent repeated endoscopy/biopsy sampling (mean time elapsing between the two procedures = 54 months; range 24-108). Paired histology showed a significant (P = 0.009) trend towards a stage progression [the stage increased in 25/116 cases (22%); it remained unchanged in 87/116 cases (75%)]. In autoimmune gastritis, the cancer risk is restricted to high-risk gastritis stages (III-IV), and is associated mainly with concomitant H. pylori infection. OLGA staging consistently depicts the time-dependent organic progression of the autoimmune disease and provides key information for secondary gastric cancer prevention strategies.

Epidemiology of Helicobacter pylori Infection and Public Health Implications

This review summarizes studies on the epidemiology and public health implications of Helicobacter pylori published in peer-reviewed journals from April 2010 through March 2011. Prevalence rates vary widely between different geographical regions and ethnic groups. An interesting study from the USA identified the degree of African ancestry as an independent predictor of H. pylori infection. Two studies have demonstrated early childhood as the period of transmission of infection and identified an infected sibling as an important risk factor. An oral-oral route of spread has been substantiated with several studies showing the presence of H. pylori in the oral cavity. Studies have shown the presence of H. pylori in drinking water and the role of poor living conditions and sanitation in H. pylori infection, supporting an oral-fecal route of spread. Screening for H. pylori as a gastric cancer pre-screening strategy has been described in Japan, and the importance of H. pylori eradication as a gastric cancer-prevention strategy has now been further emphasized in Japanese guidelines. Two studies have shown a decrease in the burden of dyspepsia and peptic ulcer disease with H. pylori eradication.