Association of Helicobacter pylori infection and environmental factors in non-cardia gastric cancer in Japan

Nitrosamine and related food intake and gastric and oesophageal cancer risk: A systematic review of the epidemiological evidence

AIM: To study the association between nitrite and nitrosamine intake and gastric cancer (GC), between meat and processed meat intake, GC and oesophageal cancer (OC), and between preserved fish, vegetable and smoked food intake and GC.

METHODS: In this article we reviewed all the published cohort and case-control studies from 1985-2005, and analyzed the relationship between nitrosamine and nitrite intake and the most important related food intake (meat and processed meat, preserved vegetables and fish, smoked foods and beer drinking) and GC or OC risk. Sixty-one studies, 11 cohorts and 50 case-control studies were included.

RESULTS: Evidence from case-control studies supported an association between nitrite and nitrosamine intake with GC but evidence was insufficient in relation to OC. A high proportion of case-control studies found a positive association with meat intake for both tumours (11 of 16 studies on GC and 11 of 18 studies on OC). A relatively large number of case-control studies showed quite consistent results supporting a positive association between processed meat intake and GC and OC risk (10 of 14 studies on GC and 8 of 9 studies on OC). Almost all the case-control studies found a positive and significant association between preserved fish, vegetable and smoked food intake and GC. The evidence regarding OC was more limited. Overall the evidence from cohort studies was insufficient or more inconsistent than that from case-control studies.

CONCLUSION: The available evidence supports a positive association between nitrite and nitrosamine intake and GC, between meat and processed meat intake and GC and OC, and between preserved fish, vegetable and smoked food intake and GC, but is not conclusive.

Antioxidant Vitamins and Risk of Gastric Cancer: A Case-Control Study in Portugal

We quantified the effect of antioxidant vitamins in gastric cancer risk, taking into account Helicobacter pylori seropositivity and overall fruit and vegetable intake. Incident cases were identified in two large hospitals in Porto, Portugal, and controls were randomly sampled among city dwellers. Food intake was assessed with a previously validated semiquantitative food-frequency questionnaire. A commercially available chromatographic immunoassay was used for the detection of immunoglobulin G antibodies. Complete questionnaire information and serum samples were available for 233 cases and 311 controls. Compared with subjects in the lowest tertile of dietary intake, the odds ratios (ORs) for those in the highest were 0.85 (95% confidence interval, CI = 0.45-1.60) for vitamin C, 1.04 (95% CI = 0.60-1.80) for vitamin E, and 1.33 (95% CI = 0.77-2.30) for provitamin A carotenoids after further adjusting for fruit and vegetable consumption. Fruit and vegetables remained an independent protective factor (OR = 0.45; 95% CI = 0.23-0.89) after further adjustment for the intake of antioxidant vitamins. H. pylori status had no significant interaction with dietary items. Factors other than H. pylori infection and intake of vitamin C and provitamin A carotenoids seem to account for the inverse association between fruit and vegetable consumption and 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.

Fruit and vegetable intake and the risk of stomach and oesophagus adenocarcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC-EURGAST)

It is considered that fruit and vegetable (F&V) protect against oesophagus and gastric cancer (GC). However, 2 recent meta-analyses suggest that the strength of association on GC seems to be weaker for vegetables than for fruit and weaker in cohort than in case-control studies. No evidence exists from cohort studies about adenocarcinoma of oesophagus (ACO). In 521,457 men and women participating in the EPIC cohort in 10 European countries, information of diet and lifestyle was collected at baseline. After an average of 6.5 years of follow-up, a total of 330 GC and 65 ACO, confirmed and classified by a panel of pathologists, was used for the analysis. We examined the relation between F&V intake and GC and ACO. A calibration study in a sub-sample was used to control diet measurement errors. In a sub-sample of cases and a random sample of controls, antibodies against Helicobacter pylori (Hp) were measured and interactions with F&V were examined in a nested case-control study. We observed no association with total vegetable intake or specific groups of vegetables and GC risk, except for the intestinal type, where a negative association is possible regarding total vegetable (calibrated HR 0.66; 95% CI 0.35-1.22 per 100 g increase) and onion and garlic intake (calibrated HR 0.70; 95% CI 0.38-1.29 per 10 g increase). No evidence of association between fresh fruit intake and GC risk was observed. We found a negative but non significant association between citrus fruit intake and the cardia site (calibrated HR 0.77; 95% CI 0.47-1.22 per 100 g increase) while no association was observed with the non-cardia site. Regarding ACO, we found a non significant negative association for vegetable intake and for citrus intake (calibrated HRs 0.72; 95% CI 0.32-1.64 and 0.77; 95% CI 0.46-1.28 per 100 and 50 g increase, respectively). It seems that Hp infection does not modify the effect of F&V intake. Our study supports a possible protective role of vegetable intake in the intestinal type of GC and the ACO. Citrus fruit consumption may have a role in the protection against cardia GC and ACO.

Seroprevalence of Helicobacter pylori in dyspeptic patients and its relationship with HIV infection, ABO blood groups and life style in a university hospital, Northwest Ethiopia

AIM

To determine the prevalence of Helicobacter pylori (H pylori) among dyspeptic patients and to assess the relationship between H pylori infection, blood group, HIV infection and life style of the patients.

METHODS

In a hospital-based cross-sectional study, patients attending Outpatient Department of University of Gondar Hospital were enrolled. Socio-demographic information was collected using questionnaires. Serum was analyzed for anti-H pylori IgG antibodies using a commercial kit. HIV serostatus was determined by enzyme-linked immunosorbent assay (ELISA). Blood grouping was performed by slide agglutination tests.

RESULTS

A total of 215 dyspeptic patients were included in the study. One hundred and sixteen patients (54%) were females and 99 (46%) were males. Anti-H pylori IgG antibodies were detected in sera of 184 (85.6%) patients. The prevalence was significantly higher in patients aged 50 years and above. Twenty point five percent of the patients were found to be seropositive for HIV. No significant association was found between sex, ABO blood groups, consumption of spicy diets, socio-economic status and seropositivity for H pylori. However, alcohol consumption was significantly associated with H pylori serology.

CONCLUSION

The prevalence of H pylori infection is associated with a history of alcohol intake and older age. The effect of different diet, alcohol and socioeconomic status as risk factors for H pylori infection needs further study.

Causal role of Helicobacter pylori infection in gastric cancer

Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori (H pylori) is regarded as playing a specific role in the development of atrophic gastritis, which represents the most recognized pathway in multistep intestinal-type gastric carcinogenesis. Recent studies suggest that a combination of host genetic factors, bacterial virulence factors, and environmental and lifestyle factors determine the severity of gastric damage and the eventual clinical outcome of H pylori infection. The seminal discovery of H pylori as the leading cause of gastric cancer should lead to effective eradication strategies. Prevention of gastric cancer requires better screening strategies to identify candidates for eradication.

Of microbe and man: determinants ofHelicobacter pylori-related diseases

The human gastric pathogen Helicobacterpylori infects the human gastric mucus layer of approximately half of the world's population. Colonization with this bacterium results in superficial gastritis without clinical symptoms, but can progress into gastric or duodenal ulcers, gastric malignancies and mucosa-associated lymphoid tissue-lymphomas. Disease outcome is affected by a complex interplay between host, environmental and bacterial factors. Irrespective of disease outcome, the majority of H. pylori infected individuals remain colonized for life. Changing conditions in the human gastric mucosa may alter gene expression and/or result in the outgrowth of more fit H. pylori variants. As such, H. pylori is a highly flexible organism that is optimally adapted to its host. the heterogeneity in H. pylori populations make predictions on H. pylori-related pathogenesis difficult. In this review, we discuss host, environmental and bacterial factors that are important in disease progression. Moreover, H. pylori adaptive mechanisms, which allow its life-long survival and growth in the gastric mucosa are considered.

Helicobacter pylori but not high salt induces gastric intraepithelial neoplasia in B6129 mice

Helicobacter pylori is responsible for most human stomach cancers. Gastric cancer also is overrepresented in populations consuming high-salt diets. Attempts to test the hypothesis that high salt promotes H. pylori carcinogenesis have been hindered by the lack of a wild-type mouse model. Based on pilot observations of unexpectedly early gastric adenocarcinoma in C57BL/6 x 129S6/SvEv (B6129) mice infected with Helicobacter felis, we conducted a study to characterize H. pylori infection in these mice and to determine whether high salt promotes tumorigenesis. Male and female mice were gavaged with H. pylori Sydney strain-1 or vehicle only and divided into four groups based on infection status and maintenance on a basal (0.25%) or high (7.5%) salt diet. In uninfected mice, the high-salt diet enhanced proliferation and marginally increased parietal cell mucous metaplasia with oxyntic atrophy. Lesions in H. pylori infected mice without regard to diet or gender were of equivalent severity and characterized by progressive gastritis, oxyntic atrophy, hyperplasia, intestinal metaplasia, and dysplasia. Infected mice on the high-salt diet exhibited a shift in antimicrobial humoral immunity from a Th1 to a Th2 pattern, accompanied by significantly higher colonization and a qualitative increase in infiltrating eosinophils. No mice developed anti-parietal cell antibodies suggestive of autoimmune gastritis. At 15 months of age infected mice in both dietary cohorts exhibited high-grade dysplasia consistent with gastric intraepithelial neoplasia. In summary, we report for the first time H. pylori-induced gastric intraepithelial neoplasia in a wild-type mouse model and show no additive effect of high-salt ingestion on tumor progression.

Dietary habits and stomach cancer risk in the JACC Study

BACKGROUND: Despite a declining incidence, stomach cancer is still a dominant cancer in Japan. The association between dietary habits and stomach cancer risk was investigated in a large prospective study in Japan.

METHODS: Data were obtained using a self-administered questionnaire from 1988 through 1990. Food frequency questionnaire was used to evaluate the consumption of 33 selected food items. Proportional hazard model was used to determine the hazard ratios (HRs) and their 95% confidence intervals (CIs) of stomach cancer for different levels of the dietary intakes.

RESULTS: A western style breakfast showed an inverse association with stomach cancer risk in males (HR=0.49, 95% CI: 0.35-0.70). Women who consumed liver three to four times per week and more than once per day had a significant increased risk, respectively (HR=2.02, 95% CI: 1.12-3.63, HR=3.16, 95% CI: 1.16-8.62 ). A clear dose-response relationship between the intake of liver and stomach cancer risk was observed. We found no association between stomach cancer mortality and the consumption of fruit such as mandarin orange, and vegetables such as carrots and spinach in both men and women. The consumption of high salt foods such as miso soup and pickles was also not significantly associated with the mortality of stomach cancer in both sexes.

CONCLUSION: This prospective study suggested that a western-style breakfast is associated with a lower risk of stomach cancer, although some differences in the association were seen between men and women.

A genetic variant in the gene encoding the stress70 protein chaperone family member STCH is associated with gastric cancer in the Japanese population

Association analysis, based on linkage disequilibrium between specific alleles in the candidate loci and nearby genetic markers, has been proposed to identify genes conferring susceptibility to multifactorial diseases. Using the affected sib-pair method, we previously mapped four candidate chromosomal regions, 1p32, 2q33-q35, 11p13-p14, and 21q21, for gastric cancer by linkage analysis. To identify genes involved in the disease, we performed a gene-based association analysis of 66 genes, located on 21p11-21q22, using 126 single nucleotide polymorphisms (SNPs) as genetic markers in 373 patients with 250 controls. We found a significant association of five SNPs in the stress70 protein chaperon family member STCH gene with gastric cancer, especially with the non-cardia localization subgroup (P=0.0005-0.02, odds ratio=1.44-1.72). Comparisons of haplotype frequency showed significant association between TTGGC haplotype and gastric cancer (P=0.0001, odds ratio=1.59). These results suggest that, in the Japanese population, STCH might be a new candidate for conferring susceptibility to this disease.

Body mass, tobacco and alcohol and risk of esophageal, gastric cardia, and gastric non-cardia adenocarcinoma among men and women in a nested case-control study

OBJECTIVES

To prospectively assess the influence of body mass index (BMI), tobacco, and alcohol on the occurrence of esophageal, gastric cardia, and non-cardia gastric adenocarcinoma, and to detect any sex differences that could explain the male predominance of these tumors.

METHODS

A case-control study nested in the General Practitioner Research Database in the United Kingdom, 1994--2001. Odds ratios (ORs) were calculated with 95% confidence intervals (CI), including multivariate analysis.

RESULTS

During follow-up of 4,340,207 person-years, we identified 287 esophageal adenocarcinomas, 195 gastric cardia adenocarcinomas, 327 gastric non-cardia adenocarcinomas, and 10,000 controls. A positive association was found between overweight (BMI > 25 kg/m(2)) and esophageal adenocarcinoma (OR 1.67, 95% CI 1.22--2.30), and gastric cardia adenocarcinoma (OR 1.46, 95% CI 0.98--2.18), but not non-cardia gastric adenocarcinoma. The association between BMI and esophageal and gastric cardia adenocarcinoma were dose-dependent and seemingly independent of reflux. No strong sex differences were identified. Smokers, particularly females, were at increased risk of all studied adenocarcinomas, while no association with alcohol was found.

CONCLUSIONS

Overweight increases risk of esophageal and gastric cardia adenocarcinoma, while tobacco smoking increases risk of esophageal, gastric cardia, and non-cardia gastric adenocarcinoma. The male predominance is not explained by sex differences in risk factor profiles of the studied exposures.

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The cag pathogenicity island of Helicobacter pylori is disrupted in the majority of patient isolates from different human populations

The cag pathogenicity island (cag-PAI) is one of the major virulence determinants of Helicobacter pylori. The chromosomal integrity of this island or the lack thereof is speculated to play an important role in the progress of the gastroduodenal pathology caused by H. pylori. We determined the integrity of the cag-PAI by using specific flanking and internally anchored PCR primers to know the biogeographical distribution of strains carrying fully integral cag-PAI with proinflammatory behavior in vivo. Genotypes based on eight selected loci were studied in 335 isolates obtained from eight different geographic regions. The cag-PAI appeared to be disrupted in the majority of patient isolates throughout the world. Conservation of cag-PAI was highest in Japanese isolates (57.1%). However, only 18.6% of the Peruvian and 12% of the Indian isolates carried an intact cag-PAI. The integrity of cag-PAI in European and African strains was minimal. All 10 strains from Costa Rica had rearrangements. Overall, a majority of the strains of East Asian ancestry were found to have intact cag-PAI compared to strains of other descent. We also found that the cagE and cagT genes were less often rearranged (18%) than the cagA gene (27%). We attempted to relate cag-PAI rearrangement patterns to disease outcome. Deletion frequencies of cagA, cagE, and cagT genes were higher in benign cases than in isolates from severe ulcers and gastric cancer. Conversely, the cagA promoter and the left end of the cag-PAI were frequently rearranged or deleted in isolates linked to severe pathology. Analysis of the cag-PAI genotypes with a different biogeoclimatic history will contribute to our understanding of the pathogen-host interaction in health and disease.

Botanical medicine and cancer: a review of the safety and efficacy

It is currently estimated that > 50% of all patients diagnosed with cancer explore complementary and alternative medicine - especially herbal medicine. We conducted a comprehensive review to assess the safety and efficacy of herbal medicines commonly used by patients in an attempt to: prevent cancer; treat cancer; and treat adverse effects associated with conventional cancer treatments. Current evidence suggests that Asian ginseng, garlic, green tea, tomatoes and soy intake as part of the diet may be useful in preventing various cancers; additional research is needed in order to determine the efficacy of essiac, evening primrose oil, mistletoe, reishi, shiitake and turmeric as cancer treatments; and ginger may be effective in treating chemotherapy-induced nausea and vomiting.

hOGG1 Ser326Cys polymorphism, interaction with environmental exposures, and gastric cancer risk in Japanese populations

Oxidative DNA damage caused by reactive oxygen species (ROS) generated by Helicobacter pylori (H. pylori ) infection or smoking may be a cause of gastric cancer development. 8-Hydroxydeoxyguanine (8-OHdG) formation is one of the most common types of oxidative DNA damage, while human oxoguanine glycosylase 1 (hOGG1) is responsible for repairing 8-OHdG lesions. Among several hOGG1 gene polymorphisms, the Ser-->Cys polymorphism at position 326 is related to biological function. To investigate the association between Ser326Cys hOGG1 polymorphism and gastric cancer in relation to the potential risk factors of gastric cancer and antioxidant dietary or nutrient intakes, we conducted a case-control study with 142 histologically-confirmed gastric cancer cases and 271 age, sex-matched healthy controls in Japanese populations. Overall, neither the hOGG1 Ser/Cys nor the Cys/Cys genotype was associated with risk of gastric cancer, compared with the Ser/Ser genotype. A significant interaction was observed between hOGG1 Ser/Cys or Cys/Cys genotype and atrophic gastritis (P for interaction=0.03). No significant interaction was found between hOGG1 genotype and antioxidant dietary or nutrient intakes. The results of the present study suggest that patients with atrophic gastritis in conjunction with the hOGG1 Cys allele might have a higher susceptibility to gastric cancer.