Helicobacter pylori-CagA seropositivity and nitrite and ascorbic acid food intake as predictors for Gastric Cancer

A systematic review and dose‒response meta-analysis of the association between nitrate & nitrite intake and gastroesophageal cancer risk

OBJECTIVE

The objective of this systematic review and dose‒response meta-analysis was to assess the associations between the dietary consumption of nitrate and nitrite and the risk of gastric and esophageal cancer.

METHODS

MEDLINE, Scopus, Embase, Web of Science, Proquest, and Google Scholar were searched until April 1, 2024. Articles were selected by two independent researchers on the basis of the inclusion and exclusion criteria. Data regarding the study design, type of exposure and outcomes, intervals of intake of nitrate or nitrite in each layer, OR/RR/HR of the relationship for each layer of intake, total sample size, and number of cases of gastric or esophageal cancer were extracted. The certainty of the evidence was rated via the GRADE method. The pooled odds ratios, risk ratios, and dose‒response analyses were calculated via Stata version 17.0. The best-fit dose‒response model was assessed by the P value for linearity and nonlinearity. Study heterogeneity was assessed via the I2 and Q tests.

RESULTS

We found 2124 nonredundant studies, 234 of which were potentially relevant. Eighteen articles met the inclusion criteria and were included in the review. The results of the meta-analysis revealed a significant positive association between nitrite intake and gastric cancer in both case‒control studies (OR = 1.29, 95 % CI = 1.09-1.52, P value = 0.001, I2 = 1.91 %) and cohort studies (RR = 1.17, 95 % CI = 1.00-1.37, P value = 0.04, I2 = 0.00 %). In addition, case‒control studies revealed a nonsignificant inverse association between nitrate intake and gastric cancer incidence (OR = 0.71, 95 % CI = 0.50-1.01, P value = 0.06, I2 = 74.89 %), and cohort studies (RR = 0.89, 95 % CI = 0.73-1.09, P value = 0.27, I2 = 0.00 %). Case‒control studies also revealed no significant correlation between nitrite intake and esophageal cancer incidence (OR = 1.48, 95 % CI = 0.91 to 2.42, P value = 0.12, I2 = 0.001 %). Nitrites correlated linearly with gastric cancer (linearity P value = 0.001). The most appropriate fit models for the relationship between nitrate and gastric cancer were both piecewise linear and natural polynomial regression (quadratic) models (P values = 0.003 and 0.005, respectively). There was no significant publication bias.

CONCLUSION

According to this meta-analysis, high consumption of nitrites was associated with an increased risk of gastric cancer in case‒control and cohort studies with a linear regression model, and dietary nitrate intake was not associated with the risk of gastric cancer in either case‒control or cohort studies. These findings are inconclusive and require confirmation in future prospective studies with robust methodologies and adjustments for potential confounders.

Association of Dietary Nitrate, Nitrite, and N-Nitroso Compounds Intake and Gastrointestinal Cancers: A Systematic Review and Meta-Analysis

N-nitroso compounds (NOCs) are a class of chemical carcinogens found in various environmental sources such as food, drinking water, cigarette smoke, the work environment, and the indoor air population. We conducted a systematic review and meta-analysis to investigate the links between nitrate, nitrite, and NOCs in food and water and the risk of gastrointestinal (GI) cancers, including esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), and pancreatic cancer (PC). A systematic search of the literature in Scopus, PubMed, Google Scholar, Web of Science, ScienceDirect, and Embase was performed for studies on the association between NOCs in drinking water and food sources and GI cancers. Forest plots of relative risk (RR) were constructed for all the cancer sites and the intake sources. The random-effects model was used to assess the heterogeneity between studies. Forty articles were included after removing duplicate and irrelevant articles. The meta-analysis indicated that the intake of high dose vs. low dose of these compounds was significantly associated with the overall GI cancer risk and nitrite (RR = 1.18, 95% CI = 1.07-1.29), and N-nitrosodimethylamine (NDMA) (RR = 1.32, 95% CI = 1.06-1.65). We found that dietary nitrite intake increased GC (RR = 1.33, 95% CI = 1.02-1.73), and EC (RR = 1.38, 95% CI = 1.01-1.89). Additionally, dietary NDMA intake increased the risk of CRC (RR = 1.36, 95% CI = 1.18-1.58). This meta-analysis provides some evidence that the intake of dietary and water nitrate, nitrite, and NOCs may be associated with GI cancers. In particular, dietary nitrite is linked to GC and EC risks and dietary NDMA intake is associated with CRC.

Assessment of hydrogeochemical characteristics and quality of groundwater resources in relation to risk of gastric cancer: comparative analysis of high- and low-risk areas in Iran

The chemical quality of groundwater supplies in two high-risk area (HRA) and low-risk area (LRA) for gastric cancer in Iran was assessed through hydrogeochemical analysis and water quality indices. For this aim, Piper and Schoeller diagrams and water quality index (WQI) were applied. In addition, exposure to nitrate via drinking water and its corresponding risk were also assessed using Monte Carlo simulation technique. Data on physicochemical properties of groundwater resources were obtained from Iran Water Resources Management Company. Sampling and analysis of tap water for nitrate concentration were conducted in two cities of Shiraz (as a representative of LRA) and Ardabil (as a representative of HRA). According to Piper diagrams, the dominant hydrogeochemical facies of groundwater supplies in HRA and LRA were Na-HCO3 (43.75%) and Ca-HCO3 (41.77%), respectively. The predominant cations in groundwater resources of HRA were found to be Na+ (68.06%) and Ca2+ (31.94%). For LRA, the typical cations were in decreasing trend: Ca2+ (39.64%) > Mg2+ (18.35%) > Na+ (17.26%). For two areas, HCO3-, SO42- and Cl- were, respectively, the most frequent anions. Two-sample Wilcoxon test showed that there were statistically significant difference between two areas in terms of anions and cations concentrations (p value < 0.05). The mean of total hardness (Ca2+ + Mg2+) concentration of water supplies in LRA (528.1 mg/L) was higher than HRA (263.1 mg/L), whereas the mean of Na+ concentration was found to be lower in LRA (90.6 mg/L) compared with HRA (108.1 mg/L). The sum of nitrate intake and its risk in LRA was higher than HRA. WQI results showed that drinking water quality in HRA and LRA ranged from excellent to poor and most water resources were of a good quality class. Further studies are suggested to investigate the role of drinking water in the etiology of gastric cancer in Iran.

Review of the health effects of berries and their phytochemicals on the digestive and immune systems

Berries are generally considered beneficial to health. This health-promoting potential has mainly been ascribed to berries' phytochemical and vitamin content, and little attention has been paid to the potential benefits of berries for the digestive tract, despite this being the first point of contact. In vivo studies that described the health effects of berries on individual parts of the digestive tract (ie, the mouth, esophagus, stomach, small and large intestine, microbiome, and immune system) were reviewed. Immune effects were included because a large part of the immune system is located in the intestine. Beneficial health effects were mainly observed for whole berry extracts, not individual berry components. These effects ranged from support of the immune system and beneficial microbiota to reduction in the number and size of premalignant and malignant lesions. These results demonstrate the potency of berries and suggest berries can serve as a strong adjuvant to established treatments or therapies for a variety of gastrointestinal and immune-related illnesses.

Environmental etiology of gastric cancer in Iran: a systematic review focusing on drinking water, soil, food, radiation, and geographical conditions

The aim of this systematic review study was to investigate the causal relationship between environmental factors and gastric cancer (GC) in Iran. In a narrow definition, the environment includes water, soil, air, and food. This definition was the main criterion for the inclusion of articles in this study. In addition, exposure to radiation and geographical conditions were considered as less investigated environmental factors in the literatures. International (PubMed, Web of Science, ScienceDirect, Scopus, and Cochran) and national (Scientific Information Database) databases were searched for articles on GC and environmental risk factors in Iran. Twenty-six articles were found to meet the inclusion criteria after title, abstract, and full text review. Risk factors identified for GC include consumption of red meat; high fat, fried, and salted meat; smoked, salted, and fried foods; some dairy products; roasted and fried seeds; strong and hot tea; and un-piped and unchlorinated drinking water, as well as exposure to radiation, loess sediment, soft and grassy soil, soil containing low concentration of molybdenum, and proximity to volcanos. Fresh fruits and vegetable, fresh fish, and honey consumption were recognized as protective agents. Given the risk factors identified, strategies to prevent GC would be educating people to choose a healthy diet and to cook and store food properly, providing access to safe drinking water, taking into account topographical and geographical conditions in choosing a right location to build residential areas, and regulating the use of radiation-emitting devices.

Association Between Nitrite and Nitrate Intake and Risk of Gastric Cancer: A Systematic Review and Meta-Analysis

BACKGROUND Studies have shown inconsistent associations of nitrite and nitrate intake with the risk of gastric cancer or its associated mortality. We performed a meta-analysis of observational studies to evaluate the correlation of nitrite and nitrate intake with the risk of gastric cancer. MATERIAL AND METHODS We searched for studies reporting effect estimates and 95% confidence intervals (CIs) of gastric cancer in PubMed, EMBASE, and the Cochrane Library through November 2018. The summary results of the included studies were pooled using a random-effects model. RESULTS Eighteen case-control and 6 prospective cohort studies recruiting 800 321 participants were included in this study. The summary results indicated that the highest (odds ratio [OR], 1.27; 95%CI, 1.03-1.55; P=0.022) or moderate (OR: 1.12; 95%CI, 1.01-1.26; P=0.037) nitrite intake were associated with a higher risk of gastric cancer. However, we noted that high (OR, 0.81; 95%CI, 0.68-0.97; P=0.021) or moderate (OR, 0.86; 95%CI, 0.75-0.99; P=0.036) nitrate intakes were associated with a reduced risk of gastric cancer. These associations differed when stratified by publication year, study design, country, the percentage of male participants, assessment of exposure, adjusted model, and study quality. CONCLUSIONS High or moderate nitrite intake was associated with higher risk of gastric cancer, whereas high or moderate nitrate intake was correlated with lower risk of gastric cancer.

The epidemiology of Helicobacter pylori infection in Europe and the impact of lifestyle on its natural evolution toward stomach cancer after infection: A systematic review

BACKGROUND

Helicobacter pylori is a recognized cause of stomach cancer, but only a fraction of infected subjects develop cancer. This systematic review 1, summarizes the prevalence of infection with this bacterium in Europe; and 2, reviews the possible impact of particular lifestyles in progression from infection to stomach cancer.

MATERIALS AND METHODS

A systematic literature search was conducted in two databases by two independent investigators. Studies describing prevalence of infection among European healthy adult populations and worldwide studies analyzing the impact of lifestyle factors in association with H. pylori on stomach cancer risk were included.

RESULTS

Variable H. pylori infection prevalence was observed depending on region and study period. The lowest infection prevalences were found in Northern Europe, while the highest were in Eastern and Southern Europe, up to 84% in Portugal and Poland. Studies on smoking, salt, and meat consumption demonstrated increased risks of developing stomach cancer among H. pylori-infected individuals, while studies relating the intake of fruit, vegetables, and vitamins demonstrated decreased risks, but the levels of significance differed importantly between studies. No significant interaction could be found for alcohol consumption or physical activity.

CONCLUSIONS

Recent data showed remaining high H. pylori infection rates in several European regions. This systematic review suggests that a number of correctable lifestyle factors could impact the disease progression toward H. pylori-associated stomach cancer. However, additional research is required to determine the potential role of targeted interventions in reducing stomach cancer development after H. pylori infection.

Association between dietary nitrate and nitrite intake and sitespecific cancer risk: evidence from observational studies

Epidemiological studies have reported inconsistent findings on the association between dietary nitrate and nitrite intake and cancer risk. We performed a meta-analysis of epidemiological studies to summarize available evidence on the association between dietary nitrate and nitrite intake and cancer risk from published prospective and case-control studies. PubMed database was searched to identify eligible publications through April 30^th, 2016. Study-specific relative risks (RRs) with corresponding 95% confidence interval (CI) from individual studies were pooled by using random- or fixed- model, and heterogeneity and publication bias analyses were conducted.

Data from 62 observational studies, 49 studies for nitrates and 51 studies for nitrites, including a total of 60,627 cancer cases were analyzed. Comparing the highest vs. lowest levels, dietary nitrate intake was inversely associated with gastric cancer risk (RR = 0.78; 95%CI = 0.67-0.91) with moderate heterogeneity (I² = 42.3%). In contrast, dietary nitrite intake was positively associated with adult glioma and thyroid cancer risk with pooled RR of 1.21 (95%CI = 1.03-1.42) and 1.52 (95%CI = 1.12-2.05), respectively. No significant associations were found between dietary nitrate/nitrite and cancers of the breast, bladder, colorectal, esophagus, renal cell, non-Hodgkin lymphoma, ovarian, and pancreas. The present meta-analysis provided modest evidence that positive associations of dietary nitrate and negative associations of dietary nitrite with certain cancers.

Clarithromycin resistance and prevalence of Helicobacter pylori virulent genotypes in patients from Southern México with chronic gastritis

In developing countries, clarithromycin resistance and frequency of re-infection are factors that contribute to high prevalence of Helicobacter pylori infection. The aim of this research was determine the prevalence of clarithromycin resistance and its relation with A2142G, A2142C and A2143G mutations in the domain V of the 23S rRNA gene of H. pylori isolates in patients from Southern Mexico with chronic gastritis. Another purpose of this work was to study the prevalence of virulent genotypes and distribution of resistant strains according to the vacA/cagA/babA2 H. pylori genotypes. One hundred forty-four patients with chronic gastritis were studied. Forty-five H. pylori strains were isolated and clarithromycin susceptibility was determined by the disk-diffusion method. The 82.2% of the strains had the combination of alleles vacA s1 m1 and the cagA gene was detected in 77.8% and 40% of the strains were babA2 positive. The vacA s1 m1 genotype was detected more frequently in cagA(+) strains, vacA s1m1/cagA(+)/babA2(-) genotype was more frequent than vacA s1m1/cagA(+)/babA2(+), 37.8% and 33.3%, respectively. Eight strains were clarithromycin resistant, in three of these, point mutations were identified, but only in one strain the A2143G mutation associated with clarithromycin resistance was found. Other point mutations (A1821G, G1826A, T1830C, A2089G, T1600C, C1601T, C1602T, T1610C, A1611C and T1633G) that have not been associated with clarithromycin resistance were identified. The highest proportion of resistant strains was vacA s1m1/cagA(+) (62.5%). In patients from southern Mexico with chronic gastritis, the prevalence of clarithromycin resistance is within internationally accepted range (17.8%) and allows continued use of triple therapy for H. pylori eradication. However, it is necessary to monitor the evolution of clarithromycin resistance in this area. The largest proportion of resistant H. pylori strains is not harboring the A2142G, A2142C and A2143G mutations in the 23S rRNA gene (87.5%). The vacA s1m1/cagA(+) genotype was the most prevalent and among clarithromycin-resistant strains, this was the predominant.

Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies-19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA)-were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI), 0.69-0.93) for dietary nitrates intake, 1.31 (95% CI, 1.13-1.52) for nitrites, and 1.34 (95% CI, 1.02-1.76) for NDMA (p for heterogeneity was 0.015, 0.013 and <0.001, respectively). The study type was found as the main source of heterogeneity for nitrates and nitrites. The heterogeneity for NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings.

The EPIYA-ABCC motif pattern in CagA of Helicobacter pylori is associated with peptic ulcer and gastric cancer in Mexican population

BACKGROUND

Helicobacter pylori chronic infection is associated with chronic gastritis, peptic ulcer, and gastric cancer. Cytotoxin-associated gene A (cagA)-positive H. pylori strains increase the risk of gastric pathology. The carcinogenic potential of CagA is linked to its polymorphic EPIYA motif variants. The goals of this study were to investigate the frequency of cagA-positive Helicobacter pylori in Mexican patients with gastric pathologies and to assess the association of cagA EPIYA motif patterns with peptic ulcer and gastric cancer.

METHODS

A total of 499 patients were studied; of these, 402 had chronic gastritis, 77 had peptic ulcer, and 20 had gastric cancer. H. pylori DNA, cagA, and the EPIYA motifs were detected in total DNA from gastric biopsies by PCR. The type and number of EPIYA segments were determined by the electrophoretic patterns. To confirm the PCR results, 20 amplicons of the cagA 3' variable region were sequenced, and analyzed in silico, and the amino acid sequence was predicted with MEGA software, version 5. The odds ratio (OR) was calculated to determine the associations between the EPIYA motif type and gastric pathology and between the number of EPIYA-C segments and peptic ulcers and gastric cancer.

RESULTS

H. pylori DNA was found in 287 (57.5%) of the 499 patients, and 214 (74%) of these patients were cagA-positive. The frequency of cagA-positive H. pylori was 74.6% (164/220) in chronic gastritis patients, 73.6% (39/53) in peptic ulcer patients, and 78.6% (11/14) in gastric cancer patients. The EPIYA-ABC pattern was more frequently observed in chronic gastritis patients (79.3%, 130/164), while the EPIYA-ABCC sequence was more frequently observed in peptic ulcer (64.1%, 25/39) and gastric cancer patients (54.5%, 6/11). However, the risks of peptic ulcer (OR = 7.0, 95% CI = 3.3-15.1; p < 0.001) and gastric cancer (OR = 5.9, 95% CI = 1.5-22.1) were significantly increased in individuals who harbored the EPIYA-ABCC cagA gene pattern.

CONCLUSIONS

cagA-positive H. pylori is highly prevalent in southern Mexico, and all CagA variants were of the western type. The cagA alleles that code for EPIYA-ABCC motif patterns are associated with peptic ulcers and gastric cancer.

Association between dietary antioxidant vitamins intake/blood level and risk of gastric cancer

We aimed to systematically evaluate the association between dietary intake/blood levels of antioxidant vitamins (vitamin C, vitamin E, β-carotene, and α-carotene) and gastric cancer risk. Systematic literature searches were conducted until April 2013 in Pubmed and Embase to identify relevant studies. Either a fixed- or a random-effects model was adopted to estimate overall odds ratios (ORs). Dose-response, meta-regression, subgroup, and publication bias analyses were applied. Forty articles were finally included in the present study. Higher dietary intake of vitamin C, vitamin E, β-carotene, and α-carotene was inversely associated with gastric cancer risk (for vitamin C, pooled OR=0.58, 95% CI 0.51-0.65; for vitamin E, pooled OR=0.65, 95% CI 0.57-0.74; for β-carotene, pooled OR=0.59, 95% CI 0.49-0.70; for α-carotene, pooled OR=0.69, 95% CI 0.52-0.93). Subgroup analyses suggested the effects of these antioxidant vitamins were different in gastric cancer subtypes. As indicated by dose-response analysis, a 100 mg/day increment of vitamin C intake conferred an OR of 0.78 (95% CI 0.67-0.90); a 15 mg/day increment of vitamin E intake conferred an OR of 0.79 (95% CI 0.66-0.94); and a 5 mg/day increment in β-carotene intake conferred an OR of 0.80 (95% CI 0.60-1.04). No significant association was observed between blood vitamin C, α-tocopherol, γ- tocopherol, β-carotene and α-carotene levels and gastric cancer risk. In conclusion, dietary intake of vitamin C, vitamin E, β-carotene and α-carotene was inversely associated with gastric cancer risk while no such association was observed for blood levels of these antioxidant vitamins, thus the results should be interpreted cautiously.

Dimovski A. Natural antioxidants in cancer prevention

It is well known that oxidative stress is an inevitable event in aerobic life. When our cells use oxygen to create energy, a variety of reactive oxygen (ROS) and nitrogen species (RNS) are generated. These species could attack DNA directly and form mutagenic lesions afterwards. According to the oxidative stress hypothesis of aging, the oxidative damage to critical molecules accumulates over the life period and could ultimately impair the body’s function. Moreover, severe oxidative stress causes mutations of tumor suppressor genes, known as one of the initial events in carcinogenesis. Furthermore, it could also play a crucial role in the promotion of the multi-step carcinogenesis. On the other hand, the human body possesses a number of mechanisms that counteract oxidative stress by producing antioxidants in situ, or externally supplied them through foods and/or supplements. Indeed, a considerable amount of laboratory evidence from chemical, cell culture, and animal studies indicates that antioxidants may slow down or possibly prevent the cancer development. Yet, the information from recent cohort, case-control and/or ecological studies is less clear. Therefore, the objectives of this review are to compile a compendium of studies, and to identify effective and promising natural antioxidant interventions.

Pathogenicity island cag, vacA and IS605 genotypes in Mexican strains of Helicobacter pylori associated with peptic ulcers

Background

Helicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric cancer. Two major virulence factors of H. pylori have been described: the pathogenicity island cag (cag PAI) and the vacuolating cytotoxin gene (vacA). Virtually all strains have a copy of vacA, but its genotype varies. The cag PAI is a region of 32 genes in which the insertion of IS605 elements in its middle region has been associated with partial or total deletions of it that have generated strains with varying virulence. Accordingly, the aim of this work was to determine the cag PAI integrity, vacA genotype and IS605 status in groups of isolates from Mexican patients with non-peptic ulcers (NPU), non-bleeding peptic ulcers (NBPU), and bleeding peptic ulcers (BPU).

Methods

The cag PAI integrity was performed by detection of eleven targeted genes along this locus using dot blot hybridization and PCR assays. The vacA allelic, cag PAI genotype 1 and IS605 status were determined by PCR analysis.

Results

Groups of 16-17 isolates (n = 50) from two patients with NPU, NBPU, and BPU, respectively, were studied. 90% (45/50) of the isolates harbored a complete cag PAI. Three BPU isolates lacked the cag PAI, and two of the NBPU had an incomplete cag PAI: the first isolate was negative for three of its genes, including deletion of the cagA gene, whereas the second did not have the cagM gene. Most of the strains (76%) had the vacA s1b/m1 genotype; meanwhile the IS605 was not present within the cag PAI of any strain but was detected elsewhere in the genome of 8% (4/50).

Conclusion

The patients had highly virulent strains since the most of them possessed a complete cag PAI and had a vacA s1b/m1 genotype. All the isolates presented the cag PAI without any IS605 insertion (genotype 1). Combined vacA genotypes showed that 1 NPU, 2 NBPU, and 1 BPU patients (66.6%) had a mixed infection; coexistence of H. pylori strains with different cag PAI status was observed in 1 NBPU and 2 BPU (50%) of the patients, but only two of these patients (NBPU and BPU) had different vacA genotypes.

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

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

Fruit and vegetable consumption and gastric cancer by location and histological type: case-control and meta-analysis

The available information favours a greater impact of environmental exposures on intestinal type gastric cancer, and risk factors for the cardia and distal stomach cancers also appear to be different. We aimed to estimate the association between fruit and vegetable intake and gastric cancer, by location and histological type. We performed a population-based case-control study and a meta-analysis of studies addressing this issue. Incident cases (n=305) were identified in two large teaching hospitals (Porto, Portugal), and controls were randomly sampled among city dwellers (n=1129). Published studies were searched through PubMed, and effects were combined with random effects meta-analysis. In our case-control study, the odds ratio (OR) for the comparison of the highest vs. lowest tertile of fruit consumption was 0.47 [95% confidence interval (CI): 0.21-1.05] for cardia, 0.53 (95% CI: 0.35-0.80) for non-cardia cancer, 0.36 (95% CI: 0.20-0.62) for intestinal, and 1.00 (95% CI: 0.53-1.90) for the diffuse histological type. For vegetables, the corresponding OR was 0.59 (95% CI: 0.26-1.35), 0.85 (95% CI: 0.58-1.26), 0.95 (95% CI: 0.57-1.57), and 0.60 (95% CI: 0.32-1.14). In meta-analysis, considering fruit consumption (highest vs. lowest category), the combined OR was 0.58 (95% CI: 0.38-0.89) for cardia, 0.61 (95% CI: 0.44-0.84) for non-cardia, 0.49 (95% CI: 0.33-0.72) for intestinal type, and 0.82 (95% CI: 0.57-1.20) for diffuse type. Vegetables also decreased the risk of cardia (OR=0.63, 95% CI: 0.50-0.79), non-cardia (OR=0.75, 95% CI: 0.59-0.95), intestinal (OR=0.61, 95% CI: 0.44-0.86), and diffuse type (OR=0.67, 95% CI: 0.44-1.01). Fruit or vegetable intake was associated with a decreased risk of gastric cancer regardless of the anatomical location and the histological type, although dietary intake had a more clear-cut protective effect on intestinal type cancers.

Helicobacter pylori and CagA seropositivity and its association with gastric and oesophageal carcinoma

OBJECTIVE

Helicobacter pylori infection is an established risk factor for non-cardia gastric adenocarcinoma. Infection with H. pylori strains harbouring the cagA pathology island may augment this association. H. pylori infection may at the same time reduce the risk for oesophageal carcinoma. However, prospective data on the association between CagA seropositivity and gastric or oesophageal carcinomas are limited. The purpose of this study was to investigate whether CagA seropositivity among H. pylori seropositive subjects is associated with gastric or oesophageal carcinomas.

MATERIAL AND METHODS

A nested case-control study was performed in the Malmö Preventive Medicine cohort consisting of 32,906 middle-aged subjects. Tumour cases were identified by the Swedish National Cancer Registry. The Western blot method Helicoblot 2.1 was used to detect H. pylori and CagA seropositivity.

RESULTS

Non-cardia gastric adenocarcinoma was associated with H. pylori seropositivity, odds ratio 17.8 (95% CI: 4.2-74.8; 67 cases). The odds ratio for CagA seropositivity among H. pylori seropositive subjects was 9.7 (95% CI: 1.5-infinity). No significant associations were found between cardia gastric adenocarcinoma and H. pylori or CagA seropositivity among H. pylori seropositive subjects; odds ratios were 1.5 (95% CI: 0.51-4.8) and 2.7 (95% CI: 0.38-infinity), respectively (24 cases). Oesophageal adenocarcinoma and oesophageal squamous cell carcinoma were not significantly associated with H. pylori seropositivity or with CagA seropositivity among H. pylori seropositive subjects; the odds ratios associated with oesophageal adenocarcinoma were 0.46 (95% CI: 0.07-2.6) and 0.38 (95% CI: 0.02-24), respectively. Corresponding odds ratios for oesophageal squamous cell carcinoma were 0.44 (95% CI: 0.15-1.2; 37 cases) and 2.0 (95% CI: 0.24-infinity), respectively.

CONCLUSIONS

CagA seropositivity among H. pylori seropositive subjects is a risk factor for non-cardia gastric adenocarcinoma.

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.

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.

Gastric cancer risk in a Mexican population: role of Helicobacter pylori CagA positive infection and polymorphisms in interleukin-1 and -10 genes

Several polymorphisms of the IL1B and IL10 gene promoters have been reported to be associated with gastric cancer risk in Caucasians. However, studies in other populations have shown differing results. We aimed to test for associations between polymorphisms in IL1B (-31 and +3954), IL10-592 and IL1RN variable number of tandem repeats (VNTR) and risk of gastric cancer in a Mexican population. DNA was extracted from sera of 183 gastric adenocarcinoma patients and 377 controls. The IL1B-31, IL1B+3954 and IL10-592 biallelic polymorphisms were discriminated using 5' Nuclease (TaqMan) assays and Pyrosequencing. The IL1RN penta-allelic VNTR polymorphism was genotyped using PCR followed by GeneScan analysis. A significant interaction was found between IL1B-31 and CagA status for the risk of intestinal-type gastric cancer (p = 0.023). Among CagA positive subjects, those with IL1B-31CC genotype had an increased risk of intestinal-type gastric cancer (OR 3.19, 95%CI = 1.05-9.68), compared to carriers of IL1B-31TT genotype. In contrast, among CagA negative subjects, no significant association of IL1B-31CC genotype with gastric cancer was observed. The IL10-592CC genotype was associated with more than doubling of the risk of the intestinal-type gastric cancer (OR, 2.20, 95%CI = 1.04-4.65). A nonsignificantly increased risk for intestinal-type gastric cancer was found in IL1RN*2 carriers (OR 1.49, 95%CI = 0.89-2.50). None of these polymorphisms was significantly related to the risk of diffuse-type gastric cancer. No significant association was found between risk of gastric cancer and the IL1B+3954 polymorphism. Individuals carrying 2 or more of the risk-associated alleles (IL1B-31C, IL1RN *2 and IL10-592C) were at increased risk for intestinal-type gastric cancer, compared to those with 0 or 1 risk-associated allele. The risk from multiple risk-associated alleles was especially high in subjects infected with CagA positive H. pylori. Our results support the identification of the IL1B-31 promoter polymorphism as a useful marker for risk of intestinal type gastric cancer in persons with CagA positive H. pylori infections.

Gastric cancer: who is at risk?

Gastric cancer is a multifactorial disease. Helicobacter pylori infection, host genetic factors and dietetic factors play an important role in the development of gastric cancer. Individuals with a positive family history of gastric cancer and/or pro-inflammatory polymorphisms of the interleukin-1 and tumor necrosis factor A genes infected by H. pylori virulent strains (cagA-, vacA s1-, vacA m1- and babA2-positive) have the highest risk of gastric cancer development. Diets rich in salted and smoked food and poor in fresh fruit and vegetables favor gastric carcinogenesis. Genetic combined with bacterial and host genotyping may allow for the identification of patients at high risk of gastric cancer who can benefit from preventive eradication therapy.