Helicobacter pylori infection in Japanese patients with adenocarcinoma of the stomach

Stool Antigen Testing, a Reliable Noninvasive Method of Assessment of Helicobacter pylori Infection Among Patients with Gastro-duodenal Disorders in Cameroon

BACKGROUND

Several techniques such as invasive and noninvasive are used for the diagnosis of H. pylori infection.

AIM

The aim of this study was to compare the results of rapid urease test, stool antigen test and serology in diagnosing H. pylori infection in Cameroon.

METHODS

Hundred patients (66 women and 34 men) were enrolled. Each patient gave a written consent. The study was approved by the local Ethical Committee of Medical Sciences and the institutional review board. From each patient, blood, stool and gastric biopsies samples were collected for H. pylori detection using three methods: stool antigen test, serology and rapid urease test (RUT), taken as gold standard. Statistical analysis was performed using Graph pad Prism 7.

RESULTS

Helicobacter pylori infection was detected in 43%, 45% and 73% of patients based on the RUT, stool antigen test and serology, respectively. The difference was statistically significant between serology and RUT (P = 0.0026), but not between stool antigens test and RUT (P = 0.288). Taken RUT as gold standard, the sensitivity, specificity, positive and negative predictive values of stool antigens test and serology were 65.11, 70.17, 62.22 and 72.72%; 88.37, 40.35, 55.77 and 82.14%, respectively. The accuracy of stool antigen test and serology was 68 and 61%, respectively.

CONCLUSIONS

Our finding showed that stool antigen test can be used as a noninvasive method of assessment of H. pylori infection in our setting. Serological test can be used in screening; however, further diagnostic tests need to be carried out to confirm seropositive cases.

Diagnosis of Helicobacter pylori Using Invasive and Noninvasive Approaches

Helicobacter pylori (H. pylori) as gram-negative and spiral microorganism is responsible for colonization in the gastric microniche for more than 50% of world population. Recent studies have shown a critical role of H. pylori in the development of peptic ulcers, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. Over the past decade, there has been a sharp interest to use noninvasive tests in diagnosis of the H. pylori infection. During the years after discovery by Marshall and Warren, it has been frequently declared that the rapid urease test (RUT) is one of the cheapest and rapid diagnostic approaches used in detecting the infection. Although the specificity and sensitivity are durable for this test, clinical experiences had shown that the ideal results are only achieved only if we take biopsies from both corpus and antrum at the same time. Given the diagnosis of the H. pylori in clinical samples, gastroenterologists are facing a long list of various molecular and nonmolecular tests. We need more in-depth researches and investigations to correctly generalize rapid and accurate molecular tests determining both bacterial identity and antibiotic resistance profile.

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.

Helicobacter Pylori "Test-and-Treat" Strategy for Management of Dyspepsia: A Comprehensive Review

OBJECTIVES:

Deciding on whether the Helicobacter pylori test-and-treat strategy is an appropriate diagnostic–therapeutic approach for patients with dyspepsia invites a series of questions. The aim present article addresses the test-and-treat strategy and attempts to provide practical conclusions for the clinician who diagnoses and treats patients with dyspepsia.

METHODS:

Bibliographical searches were performed in MEDLINE using the keywords Helicobacter pylori, test-and-treat, and dyspepsia. We focused mainly on data from randomized controlled trials (RCTs), systematic reviews, meta-analyses, cost-effectiveness analyses, and decision analyses.

RESULTS:

Several prospective studies and decision analyses support the use of the test-and-treat strategy, although we must be cautious when extrapolating the results from one geographical area to another. Many factors determine whether this strategy is appropriate in each particular area. The test-and-treat strategy will cure most cases of underlying peptic ulcer disease, prevent most potential cases of gastroduodenal disease, and yield symptomatic benefit in a minority of patients with functional dyspepsia. Future studies should be able to stratify dyspeptic patients according to their likelihood of improving after treatment of infection by H. pylori.

CONCLUSIONS:

The test-and-treat strategy will cure most cases of underlying peptic ulcer disease and prevent most potential cases of gastroduodenal disease. In addition, a minority of infected patients with functional dyspepsia will gain symptomatic benefit. Several prospective studies and decision analyses support the use of the test-and-treat strategy. The test-and-treat strategy is being reinforced by the accumulating data that support the increasingly accepted idea that “the only good H. pylori is a dead H. pylori”.

Chemoprevention for gastric cancer

Gastric cancer remains the fourth commonest cancer, and the second commonest cause of cancer death, globally. Chemopreventive strategies to reduce the incidence of gastric cancer are required, particularly as the number of deaths per year is likely to rise for the foreseeable future. There is some evidence that population screening and treatment for Helicobacter pylori in high-risk populations may reduce incidence of gastric cancer. Trials studying the effect of anti-oxidants and selenium are conflicting. A recent meta-analysis demonstrated that aspirin use led to a reduced risk of gastric cancer after 10-20 years of follow-up. There is little convincing evidence that statins have any effect on risk of gastric cancer. More trials on chemoprevention for gastric cancer are therefore urgently required.

Factors contributing to the underestimation of Helicobacter pylori-associated gastric cancer risk in a high-prevalence population

OBJECTIVE

This study aimed to identify sources of underestimation of the association between Helicobacter pylori infection and non-cardia gastric cancer, in a high-risk European population.

METHODS

Non-cardia gastric cancer patients (n = 420) recruited in two major hospitals in North of Portugal and population controls (n = 1,389) were evaluated. Whole-cell IgG antibodies against H. pylori were quantified by ELISA and Western Blot testing was conducted in a subsample (272 cases and 186 controls) allowing for the detection of current infection marker and CagA. Sex- and age-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were computed.

RESULTS

When assessing infection by ELISA, the OR for its association with gastric cancer decreases and reverts as IgG titers increased, from 1.96 (95% CI: 1.09-3.54) for borderline positive results (16.0-21.9 RU/ml) to 0.52 (95% CI: 0.36-0.74) for the highest IgG levels (> or = 102.0 RU/ml). The same pattern was observed across strata of age and blood collection timing with stronger associations among younger subjects and those providing blood samples earlier after diagnosis. The presence of CagA (Western Blot) was associated with an increased risk of gastric cancer (OR = 11.32; 95% CI: 5.64-22.73).

CONCLUSION

The use of methods with low sensitivity to detect past infection leads to a substantial underestimation of gastric cancer risk in high-prevalence settings.

Diet, H pylori infection and gastric cancer: evidence and controversies

Despite decreasing incidence and mortality rates, gastric cancer (GC) still remains the fourth most common cancer and the second most common cause of cancer-related deaths worldwide. Due to the limited treatment options, at present, prevention is likely to be the only effective means of controlling this disease. The success of a prevention strategy depends upon the understanding of etiological and pathogenic mechanisms underlying gastric carcinogenesis. The etiology of GC is multi-factorial, however, in the recent years, mounting evidence suggests that environmental factors play a key role. The most important environmental factors implicated in the pathogenesis of GC are diet and H pylori infection. Thus, modifications in lifestyle and dietary habit associated with eradication of H pylori infection could hypothetically represent the most promising potential targets for GC prevention. In this review we will address the evidence and the controversies on the role of these agents in non-cardia GC by focusing on retrospective and prospective observational studies and interventional trials.

Serological assays for identification of human gastric colonization by Helicobacter pylori strains expressing VacA m1 or m2

The Helicobacter pylori vacA gene encodes a secreted protein (VacA) that alters the function of gastric epithelial cells and T lymphocytes. H. pylori strains containing particular vacA alleles are associated with differential risk of disease. Because the VacA midregion may exist as one of two major types, m1 or m2, serologic responses may potentially be used to differentiate between patients colonized with vacA m1- or vacA m2-positive H. pylori strains. In this study, we examined the utility of specific antigens from the m regions of VacA as allele-specific diagnostic antigens. We report that serological responses to P44M1, an H. pylori m1-specific antigen, are observed predominantly in patients colonized with m1-positive strains, whereas responses to VacA m2 antigens, P48M2 and P55M2, are observed in patients colonized with either m1- or m2-positive strains. In an Asian-American population, serologic responses to VacA m region-specific antigens were not able to predict the risk of development of gastric cancer.

Familial clustering in subgroups of gastric cancer stratified by histology, age group and location

AIM

To assess the risk of gastric cancer in a Japanese patient population with the disease by stratification with histology, age, tumour location and the association with family history of gastric or non-gastric tumours.

METHODS

A retrospective analysis of 1400 consecutive patients with gastric cancer and 13,467 age- and gender-matched controls from a pre-recorded database using conditional logistic regression models.

RESULTS

Young patients (< or = 43 years of age) with gastric cancer of intestinal type had a strong association with family history of gastric cancer in first degree-relatives (OR=12.5). Moreover, when a history of gastric cancer was observed in both parents, there was an increased risk of gastric cancer intestinal type (OR=7.8), more commonly in the proximal and mid-stomach. In contrast, there was an increased risk of diffuse-type cancer when both parents suffered non-gastric cancers (OR=2.1).

CONCLUSION

These data suggest that the degree of familial clustering differ in gastric cancer subgroups stratified by histology, age, and stomach location in this Japanese population.

The association between the interleukin-1 polymorphisms and gastric cancer risk depends on the family history of gastric carcinoma in the study population

OBJECTIVES

The association between interleukin-1 polymorphisms, H. pylori and increased gastric cancer risk remains controversial.

AIMS

To compare the prevalence of these polymorphisms in individuals with two mutually exclusive diseases connected with infection, gastric cancer, and duodenal ulcer.

METHODS

121 gastric cancer and 119 duodenal ulcer patients. Genomic DNA was typed for polymorphisms at position -511, -31 in the interleukin-1beta gene (IL-1 beta) using primer extension and mass-spectrometry. Analysis of the variable number of tandem repeats in intron 2, in its receptor antagonist gene (IL-1RN) was performed by PCR and agarose gel electrophoresis.

RESULTS

All subjects were successfully genotyped for the three gene loci. IL-1 beta-511 was found to be in reverse linkage disequilibrium with IL-1 beta-31. The differences between gastric cancer and duodenal ulcer patients concerned only heterozygous variant of IL-1beta and were related to family history of gastric cancer, tumor stage, histology, site. Thus, CT carriers were found to have a higher risk of sporadic [OR 2.21 (95% CI, 1.22-3.99)], early [OR 2.81 (95% CI, 1.14-6.93)], diffuse [OR 2.48, (95% CI 1.21-5.09)] or non-cardia gastric cancer [OR 1.88 (95% CI 1.06-3.33)]. Furthermore, CT genotype was significantly more prevalent in gastric cancer patients with negative than in those with a positive family history (p = 0.039).

CONCLUSIONS

The association between the interleukin-1 polymorphisms and gastric cancer risk depends on the family history of gastric carcinoma in the study population. This phenomenon may be in part responsible for differences in results of interleukin-1 studies performed on populations with low and high gastric cancer prevalence.

Outcome following treatment for Helicobacter pylori in patients with recurrent aphthous stomatitis

OBJECTIVE

The aim of the current study was to investigate any association of Helicobacter Pylori (HP) in recurrent aphthous stomatitis (RAS) and the effect of eradication of the microorganism in the clinical course of the disease.

STUDY DESIGN

Forty-eight patients with RAS were included in the study. Twenty-six were women and 22 men, of average age 41.3 +/- 2.44. Thirty-four out of these 48 patients were HP positive and the rest 14 who were negative were used as a control group. The diagnosis of HP infection was based on the detection of specific immunoglobulin G (IgG), and immunoglubulin A (IgA) antibodies using the enzyme-linked immunoabsorbent assay technique in the serum and the saliva of the patients. In all HP carriers an eradication therapy was administered. After a 2-month period the patients were checked for HP status, using 13C-UBT. The follow up period was 6-12 months following the eradication therapy.

RESULTS

At entry patients with HP infection suffered from more severe symptoms compared with HP negative patients (P < 0.05). After the administration of HP eradication therapy, patients who had become negative showed a remarkable improvement (62.5%) with reference to recurrence of RAS as well as to symptom intensity. In 29.2% of patients symptoms had disappeared and in 33.3% of patients there was a decrease in both the frequency of recurrence and the intensity of symptoms. After the eradication treatment, the periods between recurrence of RAS in patients who had become negative were statistically significantly longer compared with those before treatment (P < 0.001). Another important observation was that patients who became negative after eradication therapy were of comparable clinical status with those who were HP negative from the beginning of the study (P > 0.05).

CONCLUSIONS

These findings support the concept of a potential association between RAS and HP.

Dietary factors and stomach cancer mortality

The present study examined the relationship between stomach cancer and the low intake of fresh fruit and vegetables and/or a high intake of pickled, preserved or salted foods and frequent use of cooking oil. During 139,390 person-year of follow-up of over 13,000 subjects, 116 died from stomach cancer. Using a Cox proportional hazards-regression analysis of relative risk (RR, 95% CI) controlling for age, sex, smoking and other dietary factors, a significant decline was found with a high consumption of green and yellow vegetables (RR=0.4, 95% CI=0.2-0.9). Reductions of between 40 and 50% were also observed with a high consumption of fresh foods (fruit, cuttle fish, tofu, and potatoes), but these associations were not statistically significant. The risk was significantly increased by the high consumption of processed meat (RR=2.7, 95% CI=1.0-7.4) and by the frequent use of cooking oil (RR=4.0, 95% CI=1.3-11.8). The high consumption of pickled food and traditional soups also increased risk, but not significantly. The findings suggest that a diet high in salt and low in vitamins may be associated with an increase in stomach cancer.

Genotyping of Helicobacter pylori in paraffin-embedded gastric biopsy specimens: relation to histological parameters and effects on therapy

OBJECTIVES

Colonization with Helicobacterpylori can lead to GI disease. Bacterial genotypes and host factors, such as acid production, can influence the progress of disease. We investigated H. pylori genotypes and histological parameters in the same paraffin-embedded gastric biopsy specimens.

METHODS

Paraffin-embedded antrum and corpus biopsy samples from 75 gastroesophageal reflux disease patients were histologically examined and tested for H. pylori vacA (s and m regions), cagA, and iceA genotypes. Patients were investigated at baseline (58 H. pylori positive and 17 H. pylori negative) and after treatment with omeprazole with or without additional antibiotic therapy.

RESULTS

Genotyping at baseline was complete in 52 (90%) of the 58 H. pylori positive patients. Multiple genotypes were detected in eight (14%) of these. Genotypes were highly consistent between antrum and corpus biopsy specimens at baseline and in follow-up samples. Genotypes from paraffin sections matched those from corresponding cultured strains in 10 selected cases. In the antrum, the degree of inflammation was associated with vacA s1 and cagA+ genotypes, and the degree of neutrophil activity was associated with the cagA+ genotype. In the corpus, the degree of inflammation was significantly associated with vacA s1, cagA+, and iceA1 genotypes and the degree of atrophy was associated with vacA s1, m1, and cagA+ genotypes, whereas the degree of neutrophil activity was associated with vacA s1 and cagA+ genotypes. vacA s2 and cagA-strains appeared more resistant to antibiotic therapy, irrespective of resistance to clarithromycin.

CONCLUSIONS

Our findings confirm the relevance of the H. pylori genotypes for the severity of gastric disease and the efficacy of antibiotic therapy.

Helicobacter muricola sp. nov., a novel Helicobacter species isolated from the ceca and feces of Korean wild mouse (Mus musculus molossinus)

A slowly growing microaerophilic Helicobacter strain was isolated from the ceca and fecal pellets of Korean wild mice (Mus musculus molossinus). This bacterial strain possessed a pair of nonsheathed bipolar flagella, was positive for urease, catalase and oxidase, and reduced nitrate to nitrite. It proved susceptible to nalidixic acid and resistant to cephalodine, and did not hydrolyze hippurate. On the basis of phenotypic characteristics and 16S rRNA gene sequence analysis, the isolate represents a new species of the genus Helicobacter, for which the name Helicobacter muricola sp. nov. is proposed; the type strain of the new species is w-06T.

Is Helicobacter pylori infection in childhood a risk factor for gastric cancer?

Helicobacter pylori infection is associated with chronic gastritis and peptic ulcer disease. Furthermore, the World Health Organization has classified this organism as a carcinogen for gastric cancer. H pylori infection is mainly acquired in childhood. Children with H pylori infection are asymptomatic except for a very small number that develop peptic ulcer disease. However, if H pylori gastritis is associated with gastric cancer, do pediatricians need to screen children for this infection and treat those who are infected? In an attempt to determine the significance of the association between H pylori and gastric cancer, we have reviewed all of the English language literature on this topic. H pylori infection seems to be associated with an increased risk of developing gastric cancer. However, only a small number of infected individuals (~1%) will develop gastric cancer. Furthermore, there are potential cofactors other than H pylori that could be equally important. The effect of the eradication of H pylori alone on the development of gastric cancer is unknown. Based on our knowledge to date, we suggest that it is not indicated to treat all children with H pylori infection because of the risk of developing gastric cancer or to institute a screening and treatment program.

Gastritis and gastric cancer. Asia

In Japan, high prevalences of H. pylori infection and AG are found, which seem to be causes for the high incidence of gastric cancer. H. pylori infection is not a sole cause of gastric cancer, however. Environmental factors, including a diet high in salt, also might be involved. For accurate diagnosis of H. pylori infection and AG, it is important to determine the locations from which the biopsy specimens are taken. Comparison of the severity of AG between different countries should be made using the same biopsy sampling system and grading criteria. Bayerdöerffer et al showed antral predominance of H. pylori colonization, but Genta et al reported more even distribution in the stomach. The authors' patients with NAG and those with antral and mild AG had similar scores of density at the six biopsy sites, whereas those with more extensive AG had the highest score at the middle body on the greater curvature. If only one biopsy specimen should be taken for the diagnosis of H. pylori infection in patients with extensive AG, the middle body of the greater curvature (site 6) would be the most suitable site. Western researchers reported that the grade of chronic and acute inflammation was significantly lower in the body than in the antrum. The authors' findings of patients with NAG were similar to those of Western researchers, but those with atrophy were not. Grades of inflammation and activity in the antrum decrease with the extension of AG. In the authors' patients, the earliest finding of the development of atrophy was found at site 1, and this was the most predominant site of atrophy in patients with extensive AG. Extension of AG into the body was determined by the finding of a biopsy specimen taken at site 3. The earliest finding of the development of intestinal metaplasia was found mostly at the middle body of the lesser curvature and next at the incisura angularis. In patients with extensive intestinal metaplasia, the scores of intestinal metaplasia at site 1 and site 3 were as high as the score at site 2. Site 6 was the last place for the invasion from the extension of AG. If biopsy specimens are taken from site 1, site 3, and site 6, they are enough for the assessment of the extent of AG and intestinal metaplasia. The Updated Sydney System recommended five biopsy sites including the incisura angularis, and its usefulness was coincidentally supported in Japan with a high prevalence of AG seen in results.

Helicobacter mesocricetorum sp. nov., A novel Helicobacter isolated from the feces of Syrian hamsters

A spiral-shaped bacterium with bipolar, single, nonsheathed flagella was isolated from the feces of Syrian hamsters. The bacterium grew as a thin spreading film at 37 degrees C under microaerobic conditions, did not hydrolyze urea, was positive for catalase and alkaline phosphatase, reduced nitrate to nitrite, did not hydrolyze hippurate, and was sensitive to nalidixic acid but resistant to cephalothin. Sequence analysis of the 16S rRNA gene and biochemical and phenotypic criteria indicate that the novel bacterium is a helicobacter. The novel bacterium is most closely related to the recently described mouse enteric helicobacter, Helicobacter rodentium. This is the first urease-negative Helicobacter species with nonsheathed flagella isolated from feces of asymptomatic Syrian hamsters. We propose to name this novel helicobacter Helicobacter mesocricetorum. The type strain is MU 97-1514 (GenBank accession number AF072471).

Association of Helicobacter pylori infection with gastric carcinoma: a meta-analysis

OBJECTIVE

As conflicting studies have recently been published, we aimed to determine if Helicobacter pylori (H. pylori) infection is associated with gastric adenocarcinoma.

METHODS

This was a meta-analysis of observational epidemiological studies.

RESULTS

A total of 42 studies met the selection criteria and were categorized by the type of study design: eight cohort and 34 case-control studies. The pooled odds ratio for H. pylori in relation to gastric carcinoma was 2.04 (95% CI: 1.69-2.45). Both patient age (OR 0.77, 95% CI: 0.68-0.89) and intestinal type cancers (OR 1.14, 95% CI: 1.05-1.25) were independent effect modifiers. Analysis of other effect modifiers showed no relationship with female gender (OR 0.76, 95% CI: 0.64-0.89), stage of cancer (advanced %) (OR 1.12, 95% CI: 0.88-1.43), anatomical location (cardia %) (OR 1.54, 95% CI: 0.32-7.39) or cohort (nested case-control) studies (OR 1.72, 95% CI: 0.32-9.17). There was significant heterogeneity among the studies (tau2 = 149; p < 0.001). The quality of the studies varied considerably, with the majority of excellent studies producing positive results and the very poor to moderate studies producing mixed results.

CONCLUSIONS

H. pylori infection is associated with a 2-fold increased risk of developing gastric adenocarcinoma.

Helicobacter pylori infection and gastric cancer: systematic review of the epidemiological studies

BACKGROUND

The published epidemiological studies of chronic Helicobacter pylori infection and gastric cancer yield conflicting results, so there is uncertainty as to whether any material association exists and, if so, how strong it is.

AIM

To review these studies quantitatively.

METHODS

A systematic review of sero-epidemiological studies published before 1998 of H. pylori and gastric cancer, as identified by computer-assisted literature searches of relevant journals, reference lists and discussions with authors. All relevant studies identified were included, subdivided by study design. The following was abstracted from published reports: adjusted odds ratio (or, in prospective studies, the risk ratio) and confidence interval, study design, type of controls, mean age, mean duration of follow-up, assay methods, location of study, and degree of adjustment for confounders.

RESULTS

The 34 retrospective studies included in total 3300 gastric cancers, but their controls were of uncertain validity. The 10 'nested' case-control comparisons in prospective studies included in total only 800 gastric cancers, and combined analysis of them yielded a risk ratio of 2.5 (95% CI: 1.9-3.4; 2P < 0.00001) for gastric cancer in people seropositive for H. pylori antibodies.

CONCLUSIONS

The prospective studies suggest that gastric cancer is 2 or 3 times as common in those chronically infected by H. pylori, but to help investigate causality, further observational studies are still needed, as are large-scale randomized trials of whether antibacterial regimens reduce the eventual incidence of gastric cancer.

Differential Helicobacter pylori infection rates in two contrasting gastric cancer risk regions of South China. China Gastric Cancer Study Group

BACKGROUND

Carriers of Helicobacter pylori are believed to have a three- to six-fold increased risk of developing gastric cancer. We have recently conducted a simultaneous cross-sectional population study on the prevalence of H. pylori infection in a cohort of asymptomatic adult volunteers in two contrasting gastric cancer risk regions of South China, Hong Kong and Changle of Fujian. Their mean annual gastric cancer mortality has been approximately 7.5 and 75/100 000 population, respectively, since the beginning of the last decade. The aim of this study was to evaluate if H. pylori prevalence bears any relationship to gastric cancer mortality rates in these two southern regions of China.

METHODS

Sera were obtained from 397 volunteers in Hong Kong. They were tested for anti-H.pylori immunoglobulin (Ig) G antibody by using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Volunteers of Changle (1456) had upper endoscopy examination and were also tested for anti-H. pylori IgG antibody by the same ELISA method.

RESULTS

The overall H. pylori infection prevalence was significantly higher in Changle (80.4%) than in Hong Kong (58.4%; P< 0.01). The high prevalence is associated with more atrophic gastritis. The overall risk of gastric cancer in people of Changle is approximately five-fold that of Hong Kong (adjusted odds ratio 4.9, 95% CI 2.5-9.8).

CONCLUSIONS

It is concluded that the prevalence of H. pylori infection rates bear a direct relationship to gastric cancer mortality rates in these two southern regions of China. Thus, H. pylori most likely plays a significant aetiopathogenetic role in gastric carcinogenesis in subjects living in Changle.

Production of monoclonal antibodies neutralizing vacuolation of cultured cells by Helicobacter pylori cytotoxin

We have succeeded in producing monoclonal antibodies which neutralize the vacuolation of rabbit kidney cells by a cytotoxin produced by Helicobacter pylori. Vacuolating activity of several H. pylori strains correlated with ELISA values using these monoclonal antibodies and culture supernatants of the strains. These results indicate that the molecules recognized by the monoclonal antibodies might be the vacuolating toxin produced by H. pylori. In addition, the sera from patients with gastritis and gastric cancer reacted strongly with the antigens captured by the monoclonal antibodies from the supernatant containing H. pylori vacuolating toxin.

Epidemiology of gastric cancer in relation to diet and Helicobacter pylori infection

Gastric cancer is the second most common fatal malignancy in the world. In China, gastric cancer is now the second most common malignancy, while in Hong Kong, the mortality rate ranked fourth among all cancers in 1995. Dietary factors in gastric carcinogenesis came mostly from case-control studies. N-Nitroso compounds from dietary sources such as preserved, smoked and salted foods were found to be associated with gastric cancer. ß-Carotene, selenium and α-tocopherol have been shown in an intervention study to be favourable in the reduction of stomach cancer mortality. Fruits and vegetables showed the most consistent results of inverse association with gastric cancer. Dietary salt intake in preserved or salted foods is also shown to be associated with gastric cancer. Tea drinking, especially green tea, has a protective effect against gastric cancer as shown in some studies. Prospective case-control studies of the association between Helicobacter pylori infection and the subsequent development of gastric cancer showed that the odds ratio ranged from 2.8 to 6.0. However, results of similar case-control studies in countries with a high frequency of gastric cancer are controversial. Infection with H. pylori leads to changes in the vitamin C content of gastric juice, reactive oxygen metabolites, epithelial cell proliferation and apoptosis. Recently, CagA-positive strains were found to be associated with gastric cancer and also duodenal ulcers. The exact role of H. pylori in gastric carcinogenesis is still under investigation. Large-scale intervention studies are underway to examine dietary supplementation, H. pylori infection and gastric cancer. Helicobacter pylori eradication for gastric cancer prevention is being conducted in China and other parts of the world. In high-risk areas, for example in China, a combination approach including H. pylori eradication and dietary supplementation may be necessary.

Meta-analysis of the relationship between Helicobacter pylori seropositivity and gastric cancer

BACKGROUND & AIMS

Reports in the literature regarding the relationship of Helicobacter pylori infection to gastric cancer are conflicting. The aim of this study was to identify the source of heterogeneity between studies.

METHODS

Meta-analysis of cohort or case-control studies with age- and/or sex-matched controls, providing raw data on H. pylori infection detected by serology, was used.

RESULTS

A fully recursive literature search identified 19 qualified studies with 2491 patients and 3959 controls. Test for homogeneity found a significant difference in odds ratio between patients with early and advanced gastric cancer (6.35 vs. 2.13; P = 0.01), patients with cardiac and noncardiac gastric cancer (1.23 vs. 3.08; P = 0.003), and population- and hospital-based controls (2.11 vs. 1.49; P < 0.001). The summary odds ratio for gastric cancer in H. pylori-infected patients is 1.92 (95% confidence interval [CI], 1.32-2.78), 2.24 (95% CI, 1.15-4.4), and 1.81 (95% CI, 1.16-2.84) for all studies, cohort, and case-control studies, respectively. H. pylori-infected younger patients have a higher relative risk for gastric cancer than older patients with odds ratios decreasing from 9.29 at age < or = 29 years to 1.05 at age > or = 70 years. H. pylori infection is equally associated with the intestinal or diffuse type of gastric cancer.

CONCLUSIONS

H. pylori infection is a risk factor for gastric cancer. The heterogeneity of reported results is caused by differences in the selection of controls, patient age, and the site and stage of gastric cancer.

Helicobacter pylori and gastric cancer in Croatia

The seroprevalence of Helicobacter pylori infection was studied in a population from two areas of Croatia with significantly different average gastric cancer (GC) cumulative incidence and mortality rates. In a random sample of 456 blood sera from both areas, which was tested with the ELISA Helicobacter pylori-antibody test, 48.8% of people in the north and 53.3% in the south of the country were found to be infected. The difference between the two areas in the seroprevalence of the infection was not statistically significant, nor did their populations differ in age, sex, educational background, smoking habit or wine consumption. Our results do not point to any association between the prevalence of Helicobacter pylori infection and the level of cumulative incidence and GC mortality levels.

Histological diagnosis of Helicobacter pylori gastritis is predictive of a high risk of gastric carcinoma

Chronic Helicobacter pylori infection has been identified as a major risk factor for the subsequent development of gastric carcinoma On the basis of seroepidemiological studies the relative risk for infected persons was estimated to range between 3 and 6. Our study attempted to determine the relative risk of gastric carcinoma in H. pylori-infected individuals based on the histological evaluation of gastritis in gastric carcinoma patients in the light of a declining prevalence of H. pylori infection in Western countries. We histologically determined the H. pylori infection rate in 215 patients with early gastric carcinoma (tumor stage pT1), and compared it with that of 215 asymptomatic persons matched by age and sex who were tested by the 13C urea breath test. On the basis of these data an odds ratio of 16.7 (CI 9.6-29.1) was calculated for the relative risk of developing gastric carcinoma in H. pylori-infected people. The histological diagnosis of gastritis permits a separate risk assessment for patients with autoimmune gastritis, and by excluding these patients from the analysis we calculated an odds ratio for H. pylori-infected persons of 150 (CI 36.4-622.9). The endoscopic-histological diagnosis of H. pylori infection is associated with an increased risk of the subsequent development of gastric carcinoma of approximately 150-fold compared with H. pylori-negative patients who do not have chronic atrophic corpus gastritis of the autoimmune type (type A gastritis).

Association between Helicobacter pylori and gastric carcinoma in the city of Malmö, Sweden. A prospective study

BACKGROUND

We have investigated the association between Helicobacter pylori and gastric carcinoma through a nested case-control study in a single city.

METHODS

From a cohort of 32,906 residents recruited from 1974 through 1992, 56 cases of gastric adenocarcinoma and 224 matched controls were selected. The mean interval between serum collection and diagnosis was 5.7 years. Frozen serum or plasma samples were analysed for IgG antibodies against H. pylori with an enzyme-linked immunosorbent assay.

RESULTS

The overall seropositivity prevalence in gastric cancer cases was 82%, compared with 49% in controls, giving an odds ratio (OR) of 5.0 (95% confidence interval (CI), 2.2-11.5). Partial gastrectomy because of peptic ulcer 5 to 36 year before diagnosis of gastric cancer could be a confounding factor. With exclusion of 10 such cases, H. pylori seropositivity among cases was 78%, as compared with 50% in matched controls (OR, 3.9; 95% CI, 1.7-9.2). Tumours of the cardia were not associated with H. pylori (OR, 0.92; 95% CI, 0.23-3.7), which is in contrast to tumours of the fundus, corpus, and antrum, which were significantly associated (OR, 11.1; 95% CI, 2.4-71.8). This difference in location was significant (P < 0.01).

CONCLUSION

There is a significant association between prior infection with H. pylori and later development of gastric carcinoma, and the association is related to noncardia gastric cancer.

What remaining questions regarding Helicobacter pylori and associated diseases should be addressed by future research? View from the Far East

Based on the findings of several epidemiological studies, it is believed that Helicobacter pylori infection is closely associated with gastric cancer. Because some abnormalities, such as severe inflammation in the gastric mucosa, impaired secretion of vitamin C, and increased gastric cell proliferation, improve after cure of the infection, anti-H. pylori therapy may reduce the incidence of gastric cancer. In Japan, the odds ratios for the development of atrophic gastritis and gastric cancer in H. pylori-positive patients are not as high as those reported in Europe and the United States. These findings suggest that factors other than H. pylori may exert a considerable influence on the development of atrophic gastritis and gastric cancer in Japan. It is not known whether atrophy and intestinal metaplasia, possible precursors of gastric cancer, are reversible. H. pylori infection is associated with a "gastritis, intestinal metaplasia, and gastric cancer sequence," but it remains obscure whether the infection is directly associated with the development of gastric cancer. We do not know which age group of patients should be given anti-H. pylori therapy for the prevention of gastric cancer. To elucidate whether the eradication of H. pylori can prevent gastric cancer, a Japanese intervention trial is now in progress.

Helicobacter pylori infection and gastric cancer. A nested case-control study in a rural area of Japan

We conducted a seroepidemiological nested case-control study to determine the association of gastric cancer with Helicobacter pylori infection and atrophic gastritis. A cohort of 2858 participants in an annual multiphasic health check-up were followed for eight years. Data for 45 gastric cancer cases and 225 sex-, age-, and address-matched control subjects were analyzed. Helicobacter pylori infection was determined by IgG antibodies, and atrophic gastritis was diagnosed by both serum pepsinogen I level (< or = 70 ng/ml) and the pepsinogen I/II ratio (< or = 3.0). Univariate analysis showed that Helicobacter pylori and atrophic gastritis were significantly associated with gastric cancer. In a multivariate analysis, atrophic gastritis was associated with significantly increased risk of cancer (odds ratio, 3.38; 95% confidence interval, 1.54-7.42); however, Helicobacter pylori was not associated with cancer (odds ratio, 1.84; 95% confidence interval, 0.59-5.72). These results suggest that Helicobacter pylori infection alone is not directly associated with gastric carcinogenesis but has an indirect relation to gastric cancer through the development of atrophic gastritis.

Relation between histologic subtypes and location of gastric cancer and Helicobacter pylori

BACKGROUND

Epidemiologic studies have consistently shown an association between Helicobacter pylori infection and gastric cancer, and it is now widely accepted that this organism plays a role in the pathogenesis of this tumor. Nevertheless, there are discrepant results on its relationship with the histologic type and location of gastric cancer within the stomach. The aim of this study was to determine the seroprevalence of H. pylori in a group of gastric cancer patients and the association between H. pylori and specific histologic types of gastric cancer and tumor location within the stomach.

METHODS

Systemic IgG antibodies against H. pylori were assayed using an enzyme-linked immunosorbent assay technique in 48 patients (male to female ratio, 31:17; age range, 39-88 years; mean, 69 years) with histologically confirmed gastric cancer and 50 controls (male to female ratio, 33:17; age range, 40-77 years, mean, 64 years).

RESULTS

Thirty-one cases of gastric cancer were of the intestinal type, and 12 of the diffuse type; the remaining 5 were unclassified. Thirteen gastric cancers were located in the distal stomach (antrum/pylorus), 12 in the body, and 5 in the proximal stomach (cardia/fundus); the remaining 17 were unclassified because the tumor extended towards more than one location. The overall seroprevalence of H. pylori in patients with gastric cancer and controls was 85.4% and 66%, respectively (P < 0.05). The seroprevalence increased with increasing age in cancer patients, but the difference was not significant. H. pylori seroprevalence among patients with the intestinal type of gastric cancer was higher than in those with the diffuse type (P < 0.05). The prevalence of H. pylori infection was higher among patients with the cancer located distally than in those with the cancer located proximally (P < 0.05).

CONCLUSIONS

H. pylori seroprevalence was higher in gastric cancer patients than in controls. The prevalence of H. pylori infection in intestinal-type gastric cancer was clearly higher than in the diffuse type and in the control group. An association was found between H. pylori infection and tumors located distally (antrum/pylorus).

Helicobacter pylori infection in young patients with gastric carcinoma

BACKGROUND

Helicobacter pylori infection has been linked with chronic atrophic gastritis and gastric cancer. This case-control study was performed to investigate a possible relationship between H. pylori infection and gastric cancer in young age groups.

METHODS

Gastrectomy and/or biopsy samples were collected from 50 consecutive patients 45 years old or younger treated between 1980 and 1994 for noncardiac gastric cancer. The control group consisted of age- and sex-matched dyspeptic patients. The presence of H. pylori infection was assessed by modified Giemsa staining and immunostaining, using antibody against H. pylori.

RESULTS

H. pylori was found in 36 (72%; 95% confidence interval 60-84%) cancer patients and in 22 (43%; 30-58%) control patients (p = 0.0023, chi-square test). The odds ratio was 3.27 (1.42-7.52). Nonatrophic (superficial) gastritis was present in 30 (60%) cancer patients and in 19 (38%) (p = 0.028, chi-square test) control cases.

CONCLUSIONS

The results of the present study support the hypothesis that H. pylori is a risk factor for gastric cancer also in young age groups and in patients with a diffuse type of gastric cancer.

Helicobacter pylori and gastric carcinogenesis

BACKGROUND

Helicobacter pylori causes chronic persistent gastritis in virtually all infected subjects, leading to development of atrophic gastritis, intestinal metaplasia and eventually dysplasia and gastric cancer in a number of infected subjects. Based on the available evidence, an IARC monograph committee classified H. pylori as a class I carcinogen to humans. Prospective studies suggest that infection increases the risk for atrophic gastritis and gastric cancer at least 8-fold. In the presence of infection, the risk for atrophy and cancer seems higher if a subject becomes infected in early childhood, if infection occurs with a cagA positive strain, and if acid output is decreased.

CONCLUSION

H.pylori is a gastric carcinogen. The clinical implications and possible strategies for cancer prevention have to be delineated in the near future.

Helicobacter pylori as a risk factor for cancer

In 1985, gastric cancer was the second most common cause of cancer death in the world. The rapid decline in gastric cancer rates over the last few decades has been attributed to a decline in the prevalence of environmental risk factors for gastric cancer and/or an increase in the prevalence of protective factors. One such risk factor could be the bacterium Helicobacter pylori. Epidemiological studies have shown that areas with high gastric cancer rates often have a correspondingly high prevalence of H. pylori and prospective studies have shown that subjects with serological evidence of H. pylori infection were significantly more likely to go on to develop gastric cancer than those who did not. Helicobacter pylori itself does not appear to be either genotoxic or mutagenic. Infection is, however, associated with increased cell turnover, a chronic immune response accompanied by increased levels of reactive oxygen metabolites and a reduction in gastric levels of ascorbic acid, all conditions that could favour the development of cancer. Nonetheless, the majority of those who are infected with H. pylori do not go on to develop gastric cancer and other factors, such as the strain of the infecting organism or consumption of dietary antioxidants including vitamin C, could also affect the risk of cancer. Finally, it has been estimated that more than one third, and possibly as many as 90% of gastric cancers might be attributable to infection with H. pylori. Prevention and treatment of infection are, therefore, possible approaches to reducing gastric cancer rates. It is, however, unclear what, if any, effect eradication of the infection would have on an individual's risk of gastric cancer and, to date, anti-Helicobacter therapy has only been shown to be of potential benefit in the treatment of low grade gastric MALT lymphomas.

Helicobacter pylori infection, serum pepsinogen level and gastric cancer: a case-control study in Japan

We conducted a case-control study to evaluate the effect of Helicobacter pylori (HP) infection on the risk of gastric cancer in Tokyo, Japan. The sera at the time of diagnosis from 282 gastric cancer cases and 767 sex- and age-matched cancer-free controls were tested for the presence of anti-HP IgG antibody (HM-CAP ELISA kit) and serum pepsinogen (PG) level (PG I and PG II Riabead). No significant association was observed in all sets [matched odds ratio (OR) = 1.04, 95% confidence interval: 0.73-1.49]. In subgroup analyses, however, an association was suggested in females [OR = 1.57], a younger population (< 50 years) [OR = 1.86], early cancer [OR = 1.53] and small cancer (< 40 mm) [OR = 1.55]. Furthermore, we observed a tendency for odds ratios to decrease with an increase in age or cancer growth (depth of tumor invasion and tumor size). Considering that the spontaneous disappearance of HP due to extended mucosal atrophy may lead to these decreasing odds ratios, we applied the conditional logistic model adjusted for the PG I/II ratio as a measure of atrophic gastritis. This analysis showed a positive association with HP infection in all sets [OR = 1.69; 1.01-2.81], distal cancer [OR = 1.88; 1.07-3.31] and intestinal-type cancer [OR = 3.76; 1.39-10.18]. We concluded that the risk of cancer associated with HP infection may be underestimated in studies with cross-sectional exposure because of spontaneous disappearance of HP due to extended mucosal atrophy.