Diet and chronic atrophic gastritis: a case-control study

Dietary Factors and Gastric Intestinal Metaplasia Risk Among US Veterans

BACKGROUND

Studies on diet and gastric intestinal metaplasia (GIM) risk are lacking in US populations.

AIM

To determine the associations of dietary factors and risk of GIM among a US population with typical American diet.

METHODS

We analyzed data from a cross-sectional study of veterans attending primary care and endoscopy clinics at the Houston VA Medical Center. Patients completed a 110-item Block Food Frequency Questionnaire then underwent upper endoscopy with gastric mapping biopsies. We compared cases defined by GIM on ≥ 1 non-cardia gastric biopsy to controls without GIM. Associations of dietary factors and GIM were estimated using logistic regression models as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Among 423 GIM cases and 1796 controls, cases were older (62.1 vs. 59.9 years) and more likely to be male (97.2% vs. 90.8%) and non-White (58.6% vs. 39.0%). GIM cases had lower fat intake (percent kcal from fat tertile 1: 43.6% vs. 33.4%) and higher carbohydrate intake (percent kcal from carbohydrate T3: 41.8% vs. 33.3%) than controls. Adjusting for age, gender, race, smoking, and Helicobacter pylori, percent kcal from carbohydrates (T3 vs. T1: OR 1.35, 95% CI 1.08-1.67), fruit intake (T3 vs. T1: OR 1.28, 95% CI 1.02-1.61), and fiber intake (T3 vs. T1: OR 1.37, 95% CI 1.04-1.80) were associated with GIM. In subgroup analyses, these associations were primarily seen in non-White patients.

CONCLUSIONS

Few dietary factors, including high carbohydrate intake, are associated with increased risk of GIM in US populations, independent of H. pylori or smoking.

Gastric cancer: epidemiology, biology, and prevention: a mini review

Gastric cancer is one of the most common causes of cancer-related mortality worldwide. The objective of this article is to review the epidemiology and biology of gastric cancer risk. This literature review explores the biological, clinical, and environmental factors that influence the rates of this disease and discuss the different intervention methods that may not only increase the awareness of gastric cancer but also increase screening in efforts to reduce the risk of gastric cancer. Helicobacter pylori infection is the primary risk factor for gastric cancer. Additional risk factors include geographical location, age, sex, smoking, socioeconomic status, dietary intake, and genetics. Primary and secondary prevention strategies such as dietary modifications and screenings are important measures for reducing the risk of gastric cancer. Interventions, such as H. pylori eradication through chemoprevention trials, have shown some potential as a preventative strategy. Although knowledge about gastric cancer risk has greatly increased, future research is warranted on the differentiation of gastric cancer epidemiology by subsite and exploring the interactions between H. pylori infection, genetics, and environmental factors. Better understanding of these relationships can help researchers determine the most effective intervention strategies for reducing the risk of this disease.

Update on the Diagnosis and Management of Gastric Intestinal Metaplasia in the USA

Gastric intestinal metaplasia (GIM) is a premalignant condition that can lead to intestinal-type gastric adenocarcinoma. It is characterized by a change in the gastric mucosa to a small-intestinal phenotype. Infection with Helicobacter pylori is the most common factor associated with GIM. Although GIM is typically a histologic diagnosis, various techniques have been developed to enable the endoscopic identification of GIM. There are presently no widely accepted guidelines on screening and surveillance strategies in patients with GIM in the USA. The aim of this review is to provide an update regarding the problem, diagnosis, and management of GIM in the USA.

Gastric Cancer Screening in Common Variable Immunodeficiency

Individuals with common variable immunodeficiency (CVID) have an increased risk of gastric cancer, and gastrointestinal lymphoma, yet screening for premalignant gastric lesions is rarely offered routinely to these patients. Proposed screening protocols are not widely accepted and are based on gastric cancer risk factors that are not applicable to all CVID patients. Fifty-two CVID patients were recruited for screening gastroscopy irrespective of symptoms or blood results and were compared to 40 controls presenting for gastroscopy for other clinical indications. Overall, 34% of CVID patients had intestinal metaplasia (IM), atrophic gastritis or moderate to severe non-atrophic gastritis, which can increase the risk of gastric cancer, compared to 7.5% of controls (p < 0.01). Focal nodular lymphoid hyperplasia, a precursor lesion for gastrointestinal lymphoma, was seen in eight CVID patients (16%), one of whom was diagnosed with gastrointestinal lymphoma on the same endoscopy. High-risk gastric pathology was associated with increased time since diagnosis of CVID, smoking, Helicobacter pylori, a low-serum pepsinogen I concentration, and diarrhea, but not pepsinogen I/II ratio, iron studies, vitamin B12 levels or upper gastrointestinal symptoms. There was a lower rate of detection of IM when fewer biopsies were taken, and IM and gastric atrophy were rarely predicted by the endoscopist macroscopically, highlighting the need for standardized biopsy protocols. The prevalence of premalignant gastric lesions in patients with CVID highlights the need for routine gastric screening. We propose a novel gastric screening protocol to detect early premalignant lesions and reduce the risk of gastric cancer and gastric lymphoma in these patients.

Sex differences in urea breath test results for the diagnosis of Helicobacter pylori infection: a large cross-sectional study

Background

Helicobacter pylori causes peptic ulcer disease and gastric cancer only in a subset of infected persons. Sex differences were shown in results of urea breath test (UBT), a commonly used test for the diagnosis of H. pylori infection. However, factors that might explain these differences, or affect UBT values, are not fully understood. We examined differences in UBT values between H. pylori-infected men and women while adjusting for background characteristics such as age, body mass index (BMI), and smoking.

Methods

A cross-sectional study was undertaken using coded data from the computerized database of Maccabi Health Services in Israel. Included were adults examined for UBT during 2002–2012 and were found H. pylori positive (UBT > 3.5‰). Multivariable linear mixed models were performed to assess the relationship between sex and UBT quantitative results, while adjusting for background characteristics.

Results

A total of 76,403 patients were included (52% of examined patients during the study period). Adjusted mean UBT value was significantly higher in women 33.8‰ (95% CI 33.4, 34.1) than in men 24.9‰ (95% CI 24.5, 25.3). A significant (P < 0.001) interaction was found between sex and smoking, showing diminished sex-differences in UBT results in smokers. Adjusted mean UBT values increased significantly with age and decreased with BMI, and it was higher in people who lived in low vs high socioeconomic status communities and lower in smokers vs non-smokers.

Conclusions

Systemic differences exist between men and women in quantitative UBT results. Host-related and environmental factors might affect UBT quantitative results. These findings have clinical implications regarding confirmation of the success of H. pylori eradication after treatment in various subgroups.

Risks and Predictors of Gastric Adenocarcinoma in Patients with Gastric Intestinal Metaplasia and Dysplasia: A Population-Based Study

OBJECTIVES

Gastric intestinal metaplasia and dysplasia are precursor lesions for adenocarcinoma. The risks of progression to malignancy from these lesions are not well characterized, particularly in the US populations.

METHODS

We identified 4,331 Kaiser Permanente Northern California members who were diagnosed with gastric intestinal metaplasia or dysplasia between 1997 and 2006 and followed them through December 2013. The incident rates of gastric adenocarcinoma, relative risks in comparison with the Kaiser Permanente general population, and predictors of progression to malignancy were investigated.

RESULTS

Among 4,146 individuals with gastric intestinal metaplasia and 141 with low-grade dysplasia with 24,440 person-years follow-up, 17 and 6 cases of gastric adenocarcinoma were diagnosed, respectively, after 1 year from the index endoscopy. The incidence rate of gastric adenocarcinoma was 0.72/1,000 person-years in patients with intestinal metaplasia, with a relative risk of 2.56 (95% confidence interval (CI) 1.49-4.10) compared with the Kaiser Permanente member population, and 7.7/1,000 person-years for low-grade dysplasia, with a relative risk of 25.6 (95% CI, 9.4-55.7). The median time for gastric intestinal metaplasia to progress to adenocarcinoma was 6.1 years, and for low-grade dysplasia, 2.6 years. Hispanic race/ethnicity and history of dysplasia were associated with significantly higher risk of progression to gastric adenocarcinoma.

CONCLUSIONS

Gastric intestinal metaplasia and dysplasia are significant predictors for gastric adenocarcinoma. The low risk for malignancy associated with intestinal metaplasia does not support routine endoscopic surveillance. However, surveillance should be considered in patients at higher risks, including those with suspicious endoscopic features, presence of dysplasia, and Hispanic race/ethnicity.

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.

Association between selected oral pathogens and gastric precancerous lesions

We examined whether colonization of selected oral pathogens is associated with gastric precancerous lesions in a cross-sectional study. A total of 119 participants were included, of which 37 were cases of chronic atrophic gastritis, intestinal metaplasia, or dysplasia. An oral examination was performed to measure periodontal indices. Plaque and saliva samples were tested with real-time quantitative PCR for DNA levels of pathogens related to periodontal disease (Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, Actinobacillus actinomycetemcomitans) and dental caries (Streptococcus mutans and S. sobrinus). There were no consistent associations between DNA levels of selected bacterial species and gastric precancerous lesions, although an elevated but non-significant odds ratio (OR) for gastric precancerous lesions was observed in relation to increasing colonization of A. actinomycetemcomitans (OR = 1.36 for one standard deviation increase, 95% Confidence Interval = 0.87-2.12), P. gingivalis (OR = 1.12, 0.67-1.88) and T. denticola (OR = 1.34, 0.83-2.12) measured in plaque. To assess the influence of specific long-term infection, stratified analyses by levels of periodontal indices were conducted. A. actinomycetemcomitans was significantly associated with gastric precancerous lesions (OR = 2.51, 1.13-5.56) among those with ≥ median of percent tooth sites with PD ≥ 3 mm, compared with no association among those below the median (OR = 0.86, 0.43-1.72). A significantly stronger relationship was observed between the cumulative bacterial burden score of periodontal disease-related pathogens and gastric precancerous lesions among those with higher versus lower levels of periodontal disease indices (p-values for interactions: 0.03-0.06). Among individuals with periodontal disease, high levels of colonization of periodontal pathogens are associated with an increased risk of gastric precancerous lesions.

Vitamin C, gastritis, and gastric disease: a historical review and update

The discovery of Helicobacter pylori as the cause of gastritis and peptic ulcers ushered in the modern era of research into gastritis and into acid-peptic diseases and rekindled interest in the role of ascorbic acid in the pathophysiology and treatment of gastritis and peptic ulcer disease. Here, we review historic and modern studies on ascorbic acid and gastric diseases with an emphasis on H. pylori gastritis and its sequelae. The relationship of ascorbic acid and gastritis and peptic ulcer and its complications was extensively studied during the 1930s through the 1950s. Much of this extensive literature has been effectively "lost." Ascorbic acid deficiency was associated with all forms of gastritis (e.g., autoimmune, chemical, and infectious) due in varying degrees to insufficient intake, increased metabolic requirements, and destruction within the GI tract. Importantly, gastritis-associated abnormalities in gastric ascorbic acid metabolism are reversed by H. pylori-eradication and potentially worsened by proton pump inhibitor therapy. Diets rich in naturally occurring ascorbic acid are associated with protection of the gastric corpus from atrophy and a reduction in the incidence of gastric cancer possibly through the ability of ascorbic acid to reduce oxidative damage to the gastric mucosa by scavenging carcinogenic N-nitroso compounds and free radicals and attenuating the H. pylori-induced inflammatory cascade. Ascorbic acid supplementation was possibly associated with a decreased incidence of bleeding from peptic ulcer disease. Pharmacologic doses of ascorbic acid also may improve the effectiveness of H. pylori-eradication therapy. Occasionally, looking back can help plot the way forward.

Association between oral health and gastric precancerous lesions

Although recent studies have suggested that tooth loss is positively related to the risk of gastric non-cardia cancer, the underlying oral health conditions potentially responsible for the association remain unknown. We investigated whether clinical and behavioral measures of oral health are associated with the risk of gastric precancerous lesions. We conducted a cross-sectional study of 131 patients undergoing upper gastrointestinal endoscopy. Cases were defined as those with gastric precancerous lesions including intestinal metaplasia or chronic atrophic gastritis on the basis of standard biopsy review. A validated structured questionnaire was administered to obtain information on oral health behaviors. A comprehensive clinical oral health examination was performed on a subset of 91 patients to evaluate for periodontal disease and dental caries experience. A total of 41 (31%) cases of gastric precancerous lesions were identified. Compared with non-cases, cases were significantly more likely to not floss their teeth [odds ratio (OR) = 2.89, 95% confidence interval (CI): 1.09-7.64], adjusting for age, sex, race, body mass index, smoking status, educational attainment and Helicobacter pylori status in serum. Among participants who completed the oral examination, cases (n = 28) were more likely to have a higher percentage of sites with gingival bleeding than non-cases [OR = 2.63, 95% CI: 1.37-5.05 for a standard deviation increase in bleeding sites (equivalent to 19.7%)], independent of potential confounders. Our findings demonstrate that specific oral health conditions and behaviors such as gingival bleeding and tooth flossing are associated with gastric precancerous lesions.

Alcohol and tobacco use in relation to gastric cancer: a prospective study of men in Shanghai, China

BACKGROUND

Epidemiologic findings of tobacco and alcohol use in relation to gastric cancer are inconsistent. Well-designed prospective studies examining their relationship are sparse.

METHODS

The association between cigarette smoking/alcohol intake and gastric cancer risk was examined in a population-based prospective cohort of 18,244 middle-aged and older men in Shanghai, China, who were enrolled in the study during 1986-1989. After up to 20 years of follow-up, 391 incident gastric cancer cases were identified. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and corresponding 95% confidence intervals (95% CI).

RESULTS

Ever smokers experienced a statistically significant increased risk of gastric cancer (HR, 1.59; 95% CI, 1.27-1.99) compared with nonsmokers after adjustment for alcohol intake and other confounders. Among nondrinkers, smokers experienced 80% increased risk of gastric cancer (HR, 1.81; 95% CI,1.36, 2.41). Conversely, heavy drinkers experienced a statistically significant increase in risk of gastric cancer (HR, 1.46; 95% CI, 1.05-2.04) among all subjects and a statistically nonsignificant 80% increased risk among never smokers. Further adjustment for Helicobacter pylori serology, serum levels of beta-carotene and vitamin C, and urinary level of total isothiocyanates in combination with glutathione S-transferase (GST) M1 and GSTT1 genotypes did not materially change the associations between smoking/alcohol consumption and gastric cancer risk.

CONCLUSIONS

These results suggest that cigarette smoking and alcohol consumption may exert independent effects on the development of gastric cancer in this high-risk population.

IMPACT

Modification of these lifestyle choices may reduce the incidence of gastric cancer.

Epidemiology of premalignant gastric lesions: implications for the development of screening and surveillance strategies

Gastric cancer is one of the most common cancers worldwide; however, gastric cancer incidence varies greatly between different geographic areas. As gastric cancer is usually diagnosed at an advanced stage, the disease causes considerable morbidity and mortality. To detect gastric carcinomas at an early and curable stage, screening and surveillance seem necessary. Premalignant gastric lesions are well known risk factors for the development of intestinal type gastric adenocarcinomas. In a multistep cascade, chronic Helicobacter pylori-induced gastritis progresses through premalignant stages of atrophic gastritis, intestinal metaplasia and dysplasia, to eventually gastric cancer. Therefore, this cascade may provide a basis for early detection and treatment of gastric cancer. Epidemiology of gastric cancer and premalignant gastric lesions should guide the development of screening and surveillance strategies, as distinct approaches are required in countries with low and high gastric cancer incidences.

Sporadic gastric cancer; a complex interaction of genetic and environmental risk factors

Sporadic gastric cancer usually arises against a background of sequential mucosal changes. H. pylori superficial gastritis progresses to atrophy and intestinal metaplasia and then to dysplasia and cancer. A variety of environmental and host genetic factors influence this process and act at different stages in the pathway. Many different combinations of these risk factors may lead to cancer. Interactions also occur between environmental and genetic factors to increase or decrease their ability to influence the precancerous process. Sporadic gastric cancer is thus the consequence of complex combinations and interactions between many environmental and genetic factors.

Dietary habits and stomach cancer in Mizoram, India

BACKGROUND

An extremely high prevalence of stomach cancer was observed in Mizoram (India), where the population consumes uncommon food. The relation of food habits and stomach cancer was examined in this study.

METHODS

A hospital-based case-control study was conducted during 2001-2004 to determine the risk factors among 329 patients with histologically confirmed stomach cancer and 658 matched controls. Food habits were determined by personal interview.

RESULTS

An elevated risk of stomach cancer was observed with frequent consumption of sa-um [odds ratio (OR) 3.4] (sa-um is fermented pork fat, a traditional food) and with frequent consumption of smoked dried salted meat (OR 2.8) and fish (OR 2.5). Soda (alkali), used as a food additive, increased the risk of stomach cancer (OR 2.9). Helicobacter pylori infection was not found to be an independent risk factor for carcinogenesis of stomach cancer in this study. However, when H. pylori infection interacted with consumption of sa-um or smoked dried meat, it showed a significant association.

CONCLUSION

Peculiar food habits in Mizoram might be associated with the high prevalence of stomach cancer in Mizoram along with other factors. H. pylori infection might increase the risk of stomach cancer, or it may play a role as a promoter of stomach cancer in Mizoram.

Age-related changes in oxidative DNA damage and benzo(a)pyrene diolepoxide-I (BPDE-I)-DNA adduct levels in human stomach

This study was conducted in order to obtain information on the association between age and oxidative DNA damage and benzo[a]pyrene diolepoxide-I (BPDE-I)-DNA adduct levels in the stomach tissues of normal subjects (n = 113). Subjects ranged from 17 to 75 yr. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, were measured by high-performance liquid chromatography-electrochemical detector (HPLC-ECD). BPDE-I-DNA adduct levels were quantitatively measured by enzyme-linked immunosorbent assay (ELISA) using the monoclonal antibody 8E11. Increase in 8-OHdG levels was observed in subjects from 31 to 60 yr of age. Higher levels of 8-OHdG were observed in the stomach tissues of those in the 51-60 yr old group. Although Helicobacter. Pylori-positive group subjects had higher 8-OHdG levels than those in the H. pylori-negative group, no age-related changes in 8-OHdG levels were observed in these groups. The levels of BPDE-I-DNA adduct also markedly increased with age. Higher levels of BPDE-I-DNA adduct were observed in subjects aged 61-70 yr, but this difference was not significant from other age groups. These results provide evidence that there is a progressive age-dependent accumulation of oxidative DNA damage and of BPDE-I-DNA adducts in human stomach tissues. It is possible that such damage contributes to the known increased incidence of gastric tumor with aging.

Seroprevalences ofHelicobacter pylori infection and chronic atrophic gastritis in the united Republic of Tanzania and the Dominican Republic

OBJECTIVE

The aim of this survey was to compare the seroprevalences ofHelicobacter Pylori (H. pylori) and chronic atrophic gastritis (CAG) in Tanzania and the Dominican Republic, both of which are tropical countries, and thereafter compare the prevalences in Tanzania and the Dominican Republic with prevalences from our previous studies done in Japan (1991) and China (1996/97).

METHODS

Community-based study in which 573 inhabitants of Tanzania and 1,215 inhabitants of the Dominican Republic answered detailed questionnaires on upper digestive tract diseases, and then underwent screening for gastric cancer by serum pepsinogen and testing for antibody toH. pylori.

RESULTS

After adjusting to the 'Age-Standardized Rate' (ASR) using the world population in 1995, the seroprevalences ofH. pylori infection in male and female subjects for Tanzania (m=85.3% & f=88.2%) were very high compared to those for the Dominican Republic (m=63.5% & f=62.4%) and Japan (m=62.0% & f=46.8%), and similar to those of China (m=78.0% & f=77.3%). Also, the agestandardized prevalences of CAG in males and females for Tanzania (m-0.237& f=0.458). were higher than those of the Dominican Republic (m=0.168 & f=0.211) and China (m=0.111 & f=0.107) and compared well with those of Japan (m=0.266 & f=0.352).

CONCLUSIONS

Although Tanzania and the Dominican Republic are both developing countries, Tanzania had a very high age-standardized prevalence ofH. pylori and CAG compared to that of the Dominican Republic, which showed a trend similar to that of Japan.

Environmental Factors in Helicobacter pylori-Related Gastric Precancerous Lesions in Venezuela

Although Helicobacter pylori (HP) infection has been acknowledged to play an etiological role in gastric carcinogenesis, its relatively weak association particularly in developing countries suggests critical roles of cofactors. Among a population with an extremely high prevalence of HP infection (≈95%) in Venezuela, we examined the relationship of household characteristics, smoking, alcohol drinking, dietary consumption, and plasma nutrient levels with the prevalence of three different stages of gastric precancerous lesions, chronic atrophic gastritis (AG; n = 337), intestinal metaplasia (IM; n = 551), and dysplasia (n = 157), in comparison with those without any of these lesions (n = 1154). Length of refrigerator use was marginally inversely associated with the prevalence of the precursor lesions studied. The association was most pronounced for AG followed by dysplasia. On the other hand, smoking status was a significant predictor for IM and dysplasia. Those smoking ≥10 cigarettes/day had 1.8-fold risk of IM and 3.6-fold risk of dysplasia compared with never smokers. There were no associations with alcohol consumption. When six food groups known to be associated with stomach cancer risk in Venezuela were tested, the prevalence of these lesions progressively increased with increasing starchy vegetable consumption and decreasing fresh fruit/fruit juice consumption. The association with fruits was more evident for dysplasia and AG and that with starchy vegetables for IM and AG. However, there were no inverse associations with plasma antioxidant vitamins. These findings offer important public health implications in preventing progression of HP-associated gastric precancerous lesions in high-risk populations.

Morphometric evaluation of gastric antral atrophy: improvement after cure of Helicobacter pylori infection

OBJECTIVE

Our purpose was to find out if morphometric techniques can document long term changes in gastric antral atrophy after curing Helicobacter pylori infection with or without dietary supplementation with antioxidant micronutrients.

METHODS

Study subjects were 132 adult volunteers from a Colombian region with high gastric cancer rates. Participants were randomly assigned to ascorbic acid, beta-carotene, and anti-H. pylori treatment, following a factorial design. Gastric biopsies were obtained at baseline and after 72 months of intervention. Atrophy was evaluated by a standard visual analog scale and by morphometry.

RESULTS

Statistically significant changes in antral atrophy were detected with morphometric techniques after intervention in subjects who received anti-H. pylori treatment. A nonsignificant trend was also observed with visual scores. This effect was greater among those who were free of infection at the end of the trial. After accounting for the effect of anti-H. pylori treatment, no significant effect was noted for dietary supplementation with ascorbic acid and/or beta-carotene.

CONCLUSIONS

We conclude that gastric atrophy improves significantly after long term control of H. pylori infection. This effect can be demonstrated both by conventional histological grading and by morphometry.

Anti-inflammatory and tissue-protectant drug effects: results from a randomized placebo-controlled trial of gastritis patients at high risk for gastric cancer

BACKGROUND

The inflammatory process involving Helicobacter pylori-associated gastritis is thought to lead to epithelial damage and contribute to the development of gastric cancer. Evidence exists from animal and in vitro studies suggesting that tetracyclines have both anti-inflammatory and tissue-protectant effects unrelated to their antimicrobial activity. We attempted to modulate components of H. pylori's inflammatory process by: (i) eliminating the infection; (ii) using tetracycline to alter the host's reaction to the infection without reducing the bacterial load; and (iii) using calcium to counteract the effect of excessive dietary salt.

METHODS

We conducted a 16-week placebo-controlled clinical trial with 374 H. pylori-associated gastritis patients randomly assigned to one of five groups: (1) triple therapy consisting of metronidazole, amoxicillin and bismuth subsalicylate for 2 weeks, followed by bismuth alone for 14 weeks; (2) calcium carbonate; (3) triple therapy and calcium carbonate; (4) tetracycline; or (5) placebo.

RESULTS

Subjects in the tetracycline and triple therapy groups, but not the calcium carbonate only group, showed a reduction in inflammation and epithelial damage vs. those in the placebo group, independent of a change in H. pylori density and other factors. Our results also indicate that epithelial damage may be affected by mechanisms independent of H. pylori density or inflammation.

CONCLUSION

The results are consistent with the hypothesis that tetracycline can decrease inflammation independent of a reduction in the bacterial load. More research is needed to investigate mechanisms leading to epithelial damage which are independent of H. pylori density and inflammation.

Effect of lifestyle, smoking, and diet on development of intestinal metaplasia in H. pylori-positive subjects

OBJECTIVES

This study aimed to evaluate the influence of environmental and sociodemographic factors and the effect of smoking, alcohol, and dietary habits on the risk of gastric intestinal metaplasia (IM) in Helicobacter pylori-infected subjects.

METHODS

The investigation was based on 2598 consecutive volunteer blood donors tested for the presence of antibodies against H. pylori from March 1995 to March 1997. Endoscopy with multiple biopsies was offered to all H. pylori-positive, symptomatic subjects. The presence or absence of IM was diagnosed by gastric biopsies. A serologically H. pylori-positive subject with gastric IM was defined as a case, whereas serologically H. pylori-positive subjects without IM were used as controls. All patients answered a detailed questionnaire collecting sociodemographic characteristics and smoking, alcohol drinking, and dietary habits. Odds ratios (ORs) and their 95% CIs were estimated by unconditional logistic regression, including terms for age and sex, to assess the association between the data collected and IM.

RESULTS

Three hundred forty-four subjects with serological H. pylori infection and upper-GI symptoms underwent GI endoscopy, during which biopsies were taken for histological diagnosis. Histology revealed metaplasia in 74 subjects (21.5%). Incomplete IM was found in 37.8% of these cases. No significant associations were found between IM and anthropometric or sociodemographic factors. There was a significant association between age and IM (chi2 for trend, 6.67; p value, 0.009). Current smokers of over 20 cigarettes per day had a 4-fold risk of IM (OR, 4.75, 95% CI, 1.33-16.99). A 2-fold increased risk was found for high butter consumers (OR, 2.17; 95% CI, 1.14-4.11). No significant specific associations were found between the variables studied and complete or incomplete IM.

CONCLUSIONS

This study found that smoking and high butter consumption may increase the risk of having gastric IM in H. pylori-positive subjects.

Duodenogastric reflux is associated with antral metaplastic gastritis

BACKGROUND

It has long been suspected that duodenogastric reflux plays a role in the pathogenesis of intestinal metaplasia (IM), although recent studies have demonstrated a close association between Helicobacter pylori infection and gastroduodenal diseases, including IM. The objective of this study was to investigate the relation among IM and duodenogastric reflux, H pylori infection, and smoking.

METHODS

Subjects with "marked" characteristics of IM, all with extensive prepyloric distribution at endoscopy that was confirmed histologically, were studied as an IM group (27 men, 26 women; mean age, 64 years). A control group was comprised by subjects without characteristics of IM (29 men, 28 women; mean age, 63 years). Fasting pH, total bile acid concentration, and ammonia concentration were measured in the gastric juice of all participants. Histologic examination endoscopic biopsy specimens were evaluated histologically. H pylori infection was determined by serum antibody and urease testing, and by histology. Serum gastrin and pepsinogen concentrations, and gastric emptying time were measured. Dietary, drinking, and smoking habits were recorded. Comparisons were made between groups and analyzed statistically.

RESULTS

The pH and total bile acid concentrations were significantly higher in the IM group than the control group (p < 0.01). No significant difference in H pylori infection was found between the IM and control group. Smoking was associated with IM (odds ratio [OR], 15.74; 95% CI, 3.96 to 62.50).

CONCLUSIONS

A high pH and total bile acid concentration and smoking were associated with "marked" IM, suggesting that these factors may play a role in the development of IM.

Relationship between serologically diagnosed chronic atrophic gastritis, Helicobacter pylori, and environmental factors in Japanese men

BACKGROUND

Whereas chronic atrophic gastritis is known to be an intermediate stage in gastric carcinogenesis, information is sparse about factors associated with this precancerous lesion except for Helicobacter pylori.

METHODS

In a cross-sectional study of 566 men aged 50-55 years in the Japan Self-Defense Forces, we examined the relation of H. pylori infection, smoking, alcohol use, and dietary factors to the prevalence of chronic atrophic gastritis as determined by serum pepsinogen I and pepsinogen II (I/II ratio < 3.0. and pepsinogen I < 70 ng/ml). Chronic atrophic gastritis was classified as severe when the pepsinogen I/II ratio was < 2.0, and as moderate otherwise.

RESULTS

The overall prevalence of chronic atrophic gastritis was 35.7% (202 of 566). The seropositivity of H. pylori was associated with a 10-fold increase in the risk of chronic atrophic gastritis, and the association was much stronger for moderate atrophic gastritis. Neither cigarette smoking nor alcohol consumption was related to the overall risk of chronic atrophic gastritis. Consumption of vegetables and fruits was each unrelated to chronic atrophic gastritis whether examined as a whole or separately for moderate and severe atrophic gastritis. Green tea was related to decreased risk of severe atrophic gastritis, although not statistically significant, whereas garlic consumption showed no protective association.

CONCLUSIONS

The findings corroborate that H. pylori infection has an important role in the development of chronic atrophic gastritis in middle-aged Japanese men. Green tea consumption may be protective against the advance of atrophic gastritis. Vegetables, fruits, or garlic had no protective effect against the development of atrophic gastritis in the study.

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.

Benzo[a]pyrene diol-epoxide-I-DNA and oxidative DNA adducts associated with gastric adenocarcinoma

BPDE-I-DNA and oxidative DNA adducts (8-OHdG) were investigated in stomach tissues (tumor and tumor-adjacent) of patients (N = 211) with gastric adenocarcinoma and in normal stomach tissues (N = 113). In each stomach specimen, the levels of BPDE-I-DNA adducts were quantitatively measured by enzyme linked immunosorbent assay (ELISA) and oxidative DNA damage was measured by HPLC-ECD. Higher levels of total BPDE-I-DNA adduct were observed in tumor (4.20 +/- 0.59 fmol/microg DNA) and tumor-adjacent (3.68 +/- 0.62 fmol/microg DNA) tissues than in normal stomach tissues (2.80 +/- 0.53 fmol/microg DNA) but were not significant. In males, BPDE-I-DNA adduct was significantly higher in tumor tissues (4.25 +/- 0.42 fmol/microg DNA) than in normal tissues (2.83 +/- 0.59 fmol/microg DNA) (P < 0.05). In smokers, BPDE-I-DNA adduct was slightly higher in tumor tissues (4.92 +/- 0.82 fmol/microg DNA) than in tumor-adjacent tissues (3.99 +/- 0.92 fmol/microg DNA). Gastric cancer patients had significantly higher levels of 8-OHdG in their tumor-adjacent (7.54 +/- 0.43 residues/10(5) dG) and tumor tissues (6.29 +/- 0.39 residues/10(5) dG) than in normal tissues (2.86 +/- 0.11 residues/10(5) dG) (P < 0.001). Smokers showed higher levels of 8-OHdG in both tumor (6.44 +/- 0.62 residues/10(5) dG) and tumor-adjacent (8.12 +/- 0.68 residues/10(5) dG) tissues than in non-smokers (5.80 +/- 0.47 and 7.11 +/- 0.57 residues/10(5) dG, respectively). 8-OHdG levels were significantly increased in positive tissues with Helicobacter pylori (H. pylori) infection compared with negative tissues (P < 0.01). Also, the frequency of H. pylori infection was higher in tumor-adjacent tissues (73%) than in tumor (42%) or normal tissues (44%). These results demonstrate that there are higher levels of 8-OHdG and BPDE-I-DNA adducts in tumor and tumor-adjacent tissues than in normal tissues and that these higher levels might be related to gastric tumorigenesis, although benzo[a]pyrene could be a minor contributing component in the environment.

Failure to confirm association of vac A gene mosaicism with duodenal ulcer disease

BACKGROUND

Mosaicism of the Helicobacter pylori vac A gene comprises two families of allelic variations of the signal sequence region (s1, s2) and of the mid-region (m1, m2). Initial studies suggested that peptic ulcer disease correlated with the s1 subtype of vac A. We compared the prevalence of various vac A genotypes of H. pylori isolates obtained from duodenal ulcer (DU) patients and subjects with simple gastritis. Those isolates with s1 type were further examined to determine whether the specific vac A s1 (s1a versus s1b) genotype enabled prediction of gastroduodenal disease.

METHODS

H. pylori isolates were obtained from 38 patients with endoscopically documented DU and 39 individuals with asymptomatic H. pylori gastritis from Houston, Texas. The vac A genotype of each isolate was determined by polymerase chain reaction (PCR) amplification of genomic DNA for specific regions of the vac A gene. Those isolates with s1 vac A subtype were further examined to determine whether they had s1a or s1b mosaicism.

RESULTS

There was no difference in frequency of the s1 genotype of isolates obtained from patients with duodenal ulcer or asymptomatic H. pylori gastritis in this sample (84% versus 79%, respectively; P = 0.77). The s1/m1 vac A genotype was detected in isolates from 16 duodenal ulcer patients versus 15 with H. pylori gastritis (P = 0.82). Detailed analysis of the s1 region failed to show a correlation of either s1a or s1b with duodenal ulcer. Both s1a and s1b genotypes were detected in 24 strains, and both m1 and m2 mid-gene PCR amplicons were seen in 16 strains.

CONCLUSIONS

We were unable to use H. pylori vac A genotyping to predict type of gastroduodenal disease in our patient sample. This failure to confirm an association of vac A genotype and duodenal ulcer disease differs from samples from other regions. This most likely represents an example of differences in H. pylori strains infecting host populations in different geographic regions. This study confirms the importance of establishing statistical associations with isolates from widely separate geographic regions before concluding that disease-related associations exist.

What are the host factors that place an individual at risk for Helicobacter pylori-associated disease?

Helicobacter pylori infection is associated with duodenal and gastric ulcer disease, gastric cancer, and gastric mucosa-associated lymphoid tissue lymphoma. Although more than half the world's population harbors H. pylori, only a proportion will develop clinically significant disease. The specific clinical outcome of an individual can be examined as the modulation of host factors by H. pylori infection. Host acid-secretory status and sensitivity to gastrin can be modulated by H. pylori infection. Once H. pylori has established itself in the stomach, virtually everyone develops gastritis, and variations in gastritis patterns have been associated with different gastric acid responses to H. pylori infection. The patterns of gastritis are important because they seem to determine disease outcome. Blood group antigens have been implicated in studies of ulcer disease. Receptors to Lewis antigens in gastric mucosa indicate that host mucosal factors influence H. pylori attachment. Conversely, H. pylori strains express Lewis antigen-like molecules, suggesting an autoimmune component for some H. pylori-associated diseases. HLA genotypes may influence the host response to H. pylori infection, and those of H. pylori-infected individuals have been correlated with histological features. The clinical outcome of H. pylori infection is most likely a result of complex interactions among host, bacterial, and environmental factors. The mechanisms by which these diverse factors influence the pathogenesis of different clinical outcomes remain under investigation.

Tobacco smoking and gastric cancer: review and meta-analysis

Although declining, gastric cancer (GC) is estimated to be second in frequency worldwide. Major causes appear to be environmental rather than genetic. A relationship has been suggested between tobacco smoking and GC. A number of epidemiological studies have been performed dealing with this question. All the cohort studies showed a significantly increased risk of GC of the order of 1.5-2.5 for cigarette smokers. Evidence from case-control studies is less consistent. We have carried out a meta-analysis on the 40 studies providing a quantitative estimate of the association between GC risk and tobacco smoking. Results suggest a risk of stomach cancer among smokers of the order of 1.5-1.6 as compared to non-smokers. The summary relative risk was higher in men (1.59) than in women (1.11). Several studies examined the dose-response relationship which existed in 4 cohort studies and 6 case-control studies. We estimated the number of GC cases attributable to tobacco smoking occurring worldwide: in total, over 80,000 cases of GC (11% of all estimated cases) may be attributed to tobacco smoking each year. This figure is larger than that estimated for other cancers for which association with tobacco smoking is clearly established, such as pancreatic and renal cancers.

Ascorbic acid and gastrointestinal cancer

A literature review was made to critically evaluate the ability of ascorbic acid to modulate the incidence of gastrointestinal cancer. A comparison of preclinical, clinical, and epidemiological studies indicated that evidence for ascorbic acid as an inhibitor of carcinogenesis is stronger with regard to gastric cancer and weaker with regard to esophageal and colon/rectal cancer. Insufficient evidence currently exists regarding the oral cavity and the use of ascorbic acid in precancerous conditions such as polyposis and leukoplakia.

Geographical pathology of Helicobacter pylori infection: is there more than one gastritis?

Helicobacter pylori is the aetiological agent of chronic gastritis and a major causative factor in duodenal and gastric peptic ulcer disease; a strong association also exists with gastric cancer and primary gastric lymphoma. The prevalence of infection in adults ranges from less than 15% in developed countries to virtually 100% in less developed areas. If H. pylori infection alone was responsible for the development of gastritis, peptic ulcer disease, gastric carcinoma and primary gastric lymphoma, one would expect the frequency of all these conditions to parallel closely the prevalence of H. pylori infection. This is clearly not the case: therefore, genetic, environmental and cultural factors must act in concert with H. pylori to induce different outcomes of the infection. This paper outlines the geographic approach to the study of disease and discusses the possible application of this methodology to the inquiry into the relationship between H. pylori, atrophic gastritis and gastric cancer. Preliminary results of a study showing great variation in the prevalence of intestinal metaplasia in duodenal ulcer patients from different geographic origin are presented and briefly discussed.

Determinants of plasma pepsinogen levels in a population at high risk for stomach cancer in Venezuela

Determinants of plasma pepsinogens (PG) levels were studied in 1365 participants in a chemoprevention trial for gastric pre-cancerous lesions being conducted in Venezuela. Gastric biopsies, plasma samples and information on smoking and dietary habits were obtained at baseline examination. Both PG-I and PG-II levels increased progressively with the level of Helicobacter pylori infection in gastric biopsies, resulting in no clear trend in the I/II ratio. Instead, there was a progressive decrease in the I/II ratio with increasing degrees of infiltration of polynuclear cells and monocytes, atrophy, intestinal metaplasia and the stage of pre-cancerous lesions. The mean I/II ratios for atrophic gastritis or more advanced lesions were less than 4.0. When subjects with the I/II ratio 4 or higher were used as controls, severe reduction in the I/II ratio (< 2.0) was inversely associated with tobacco consumption. This may be due to a pharmacological effect of nicotine. The severe reduction of I/II ratio was also inversely associated with fresh fruit consumption. In addition, a decreased I/II ratio was positively associated with rice/pasta and arepas (tortilla made from corn) consumption and inversely associated with plantain consumption. Possible effects of vitamins and starchy food on the development of atrophic gastritis need to be studied further.

Cancer and occupational exposure to inorganic lead compounds: a meta-analysis of published data

OBJECTIVES

To review and summarise the epidemiological evidence on the carcinogenicity of occupational exposure to inorganic lead.

METHODS

Case-control and cohort studies were reviewed and combined for meta-analysis. Fixed and random effect methods were used to estimate the summary effects.

RESULTS

The combined results show a significant excess risk of overall cancer, stomach cancer, lung cancer, and bladder cancer, with relative risk ratios (RRs) and 95% confidence intervals (95% CIs) in the meta-analysis of 1.11 (1.05-1.17), 1.33 (1.18-1.49), 1.29 (1.10-1.50), and 1.41 (1.16-1.71) respectively. The RR (95% CI) for kidney cancer was also high, but did not reach significance (1.19 (0.96-1.48)). A separate analysis of studies of heavily exposed workers provided slightly increased RRs for cancers of the stomach (1.50) and lung (1.42).

CONCLUSIONS

The findings from the workers with heavy exposure to lead provided some evidence to support the hypothesis of an association between stomach and lung cancer and exposure to lead. The main limitation of the present analysis is that the excess risks do not take account of potential confounders, because little information was available for other occupational exposures, smoking, and dietary habits. To some extent, the risk of lung cancer might be explained by confounders such as tobacco smoking and exposure to other occupational carcinogens. The excess risk of stomach cancer may also be explained, at least in part, by non-occupational factors. For bladder and kidney cancers, the excess risks are only suggestive of a true effect because of possible publication bias.

Nitrate, nitrite and N-nitroso compounds

A risk assessment has been made on nitrate, nitrite and N-nitroso compounds encountered in the human diet. Vegetables constitute a major source of nitrate providing over 85% of the average daily human dietary intake. Nitrite and N-nitroso compounds present in the diet contribute relatively small amounts to the body burden and the major source of these biologically reactive compounds is derived from the bacterial and mammalian metabolism of ingested nitrate. Additionally, endogenous synthesis provides an important source contributing to the body burden of nitrate. Data from animal toxicological studies, human effects and epidemiological surveys have been reviewed and evaluated. It is concluded that there is no firm scientific evidence at present to recommend drastic reductions beyond the average levels of nitrate encountered in vegetables grown in keeping with good agricultural practice. Recommendations have also been made for further animal and human studies to be carried out to elucidate the potential risks to man from ingested nitrate.

Helicobacter pylori: the missing link in perspective

Helicobacter pylori, an organism responsible for a common human infection, may act as a cofactor to produce gastrointestinal disease in a significant minority. The exact mechanisms of transmission are still unclear, but likely involve direct person-to-person spread and fecal-oral or waterborne/environmental transmission. Infection is a necessary condition for the development of duodenal ulcers and chronic nonspecific gastritis. It also likely contributes to the development of gastric ulcers, and the intestinal-type gastric carcinoma, but further studies are needed to confirm these hypotheses. Multiple effective treatment regimens currently exists. We recommend using bismuth, metronidazole, and tetracycline as the initial regimen of choice. Unfortunately, the relative importance of bacterial virulence factors is still unclear when compared with host susceptibility factors, and much knowledge needs to be gained about pathogenesis before vaccine development can proceed.

Epidemiology of precancerous gastric lesions

Research over the past several decades has revealed that the major subtype of gastric cancer (intestinal gastric cancer) is an end result of a multistage transformation of the gastric mucosa over many years and that this process is mainly determined by environmental factors. Epidemiologic studies on precancerous gastric lesions, including a large population-based study of the natural history and aetiology of precancerous gastric lesions conducted in Shandong, China, are reviewed.

Subtypes of intestinal metaplasia and Helicobacter pylori

To determine whether there is a relationship between the presence of H pylori and the various subtypes of intestinal metaplasia in the gastric antrum, 2274 antral gastroscopic biopsies from 533 patients were examined. H pylori was found in 289 patients. Intestinal metaplasia in general was found in 135 patients. Type I intestinal metaplasia was found in 133 patients (98.5%), type II in 106 patients (78.5%) and type III in 21 patients (15.6%). Ninety eight of these 135 patients (72.6%) were H pylori positive and 37 patients (27.4%) were H pylori negative. No statistically significant difference was found in the prevalence of type I and II intestinal metaplasia between the intestinal metaplasia positive and H pylori positive and intestinal metaplasia negative and H pylori negative patients. Type III intestinal metaplasia was found less often in the intestinal metaplasia positive and H pylori positive patients (11.2%) as compared with intestinal metaplasia positive and H pylori negative patients (27%) (p less than 0.05). In contrast with type I and II intestinal metaplasia type III intestinal metaplasia was found more often in moderate/severe intestinal metaplasia than in mild intestinal metaplasia (p less than 0.02). Within the group of patients with moderate/severe intestinal metaplasia, type III was found less often in the H pylori positive patients (p less than 0.05). We suggest that the gastric milieu for H pylori is less appropriate in type III intestinal metaplasia positive patients. As type III intestinal metaplasia might be regarded as a marker of possibly increased gastric cancer risk, the lower prevalence of H pylori in these type III intestinal metaplasia positive patients might be the result of severe changes in mucosal architecture.

Intestinal metaplasia and Helicobacter pylori: an endoscopic bioptic study of the gastric antrum

To study the relationship between intestinal metaplasia and Helicobacter pylori infection, 2274 gastroscopic antral biopsies taken from 533 patients were examined. Overall, intestinal metaplasia was found in 135 patients (25.3%) and H pylori in 289 patients (54.2%). The prevalence of intestinal metaplasia and H pylori was age related, being more common in patients greater than or equal to 50 years compared with patients less than 50 years (intestinal metaplasia, p less than 0.001 and H pylori, p less than 0.05). Intestinal metaplasia was found more often in H pylori positive patients compared with H pylori negative patients (33.9% v 15.2%, p less than 0.001). The mean age of intestinal metaplasia positive patients who were also H pylori positive was 64 (13.3) years, whereas the mean age of intestinal metaplasia positive patients who were H pylori negative was 72 (14.7) years (p less than 0.005). The extent of intestinal metaplasia was not statistically different in the latter two groups. Although our data do not prove a causal relationship between H pylori infection and the histogenesis of intestinal metaplasia it is suggested that H pylori infection is an important factor in the development of intestinal metaplasia, which is generally recognised as a precursor lesion of intestinal type gastric carcinoma.

Epidemiological research in stomach cancer: progress over the last ten years

In this paper the progress of epidemiological research in stomach cancer during 1980-1990 is reviewed in respect to regional variation, etiology, and formation of carcinogens. The evaluation of 4 cohort and 16 case-control studies revealed a consistently inverse relationship of stomach cancer risk with raw vegetables, fruit, and wholemeal bread consumption and with vitamin C and carotene intake. Milk, cooked vegetables and vitamins A and E were not consistently found to be related to stomach cancer risk. Positive associations of increasing consumption with stomach cancer risk were occasionally found for processed or particularly prepared meat and fish, and for nitrite. Dietary nitrate intake did not appear to be related to stomach cancer risk in these studies. This latter observation is also supported by metabolic studies in high- and low-risk areas for stomach cancer. Consistently among studies, increased risk for stomach cancer was also found for later availability of refrigeration facilities in the household, non-centralized water supply (especially well water), and high salt intake. Prospective studies agreed in an increased risk for stomach cancer for cigarette smoking, but not for alcohol drinking, whereas case-control studies showed divergent results on these factors. Recent metabolic studies in high- and low-risk areas for stomach cancer or in groups with precursor lesions, with the N-nitrosoproline test as a marker for endogenous nitrosation, revealed inconsistent results. Higher nitrite concentration and increased pH in stomach juice were found to be associated with precursor conditions for stomach cancer. It is still not clear whether intake of preformed carcinogens or endogenous formation in the stomach with or without the inclusion of nitrite is the most important source of tumor-initiating or -promoting substances. Preservation or preparation of meat and fish may play an important role in this process, and vitamin C may be an inhibiting substance.

Clinical trials as etiologic research tools in Helicobacter-associated gastritis

The role of clinical trials as tools to elucidate the etiology of chronic gastritis is discussed. Three areas are briefly explored. The first one concerns the classification of chronic gastritis, a constellation of interconnected nosologic entities. The second refers to the histopathologic factors of chronic gastritis; preliminary results show that clearance of Helicobacter pylori decreases the inflammatory infiltrate and suggest that H. pylori alters cell ploidy. The third area refers to the multifactorial etiology of chronic gastritis and the role that clinical trials could play in its elucidation.

Impact of diet and smoking on risk of developing intestinal metaplasia of the stomach

A cohort of Hawaii Japanese men was assembled for epidemiologic studies of heart disease and cancer. Diet and tobacco consumption data were obtained from 1965 to 1968 and from 1971 to 1975. Biopsies from sites at maximal, intermediate, and minimal risk of intestinal metaplasia were performed on 350 men. Metaplasia was found in 234 men. Gastric cancer was found in 9/234 with metaplasia (3.8%) and 1/116 men without metaplasia (0.89%). Nitrite-rich salty foods (e.g., cured meats) were directly related to metaplasia at both examinations. Vitamin C intake did not appear to have prevented the development of intestinal metaplasia. Smoking was directly related to the presence of metaplasia, but the association was weaker than was observed for cured meats. The strong association between nitrite-rich salty foods and metaplasia appears to be uniform from one study to another, as is the lack of a consistent relation between metaplasia and either smoking or vitamin C consumption. Heavy smokers were more likely to have metaplasia than were nonsmokers, but these associations were weaker than were those with cured meats.

Diet in the epidemiology of gastric cancer

We examined the nutritional epidemiology of gastric cancer in 293 cases and neighborhood-, age-, and sex-matched controls in communities throughout the counties of Niagara, Monroe, and Erie in western New York. The interview was highly detailed, requiring two and one-half hours to complete; it attempted to provide an estimate of total calories ingested as well as of macro- and micronutrients and behaviors that could affect alimentary exposures, such as the use of refrigeration. We found that risk was enhanced by sodium, fat, and retinol. Substantial reductions in risk were associated with ingestion of carotene, especially raw vegetables (including celery, cucumbers, carrots, green peppers, tomatoes, and onions), as well as with increased use of low-temperature food storage. Both refrigeration and carotene could inhibit oxidation products that could act as carcinogens in the stomach.

Risk factors of gastric precancerous lesions in a high-risk Colombian population. II. Nitrate and nitrite

Gastric nitrite content was studied in relation to precancerous lesions of the stomach in a case-control study conducted in a high-risk Colombian population. The proportion of detectable nitrite in gastric juice and the mean pH were significantly higher among those with precancerous lesions (chronic atrophic gastritis, intestinal metaplasia, and dysplasia) than among the controls (normal and superficial gastritis); the proportion and mean pH increased with the progression of histological changes from normal to dysplasia. Nitrite was not detectable in gastric juice with a pH less than 5.0. A positive association was found between the proportion of detectable nitrite and the risk of gastric precancerous lesions. Odds ratios of 4.39 for intestinal metaplasia and 24.72 for dysplasia remained significant after controlling for confounders. This finding suggests that nitrite may be a precursor of a mutagen that targets gastric epithelial cells.

Ascorbic acid in the human stomach

Ascorbic acid, the reduced form of vitamin C, may protect against gastric cancer. Accordingly, this study assessed the variability of ascorbic acid and vitamin C in the gastric juice of 77 patients with dyspepsia. There was a vitamin C concentration gradient from gastric juice down to plasma in subjects with normal gastric mucosa, but not in those with chronic gastritis. Patients with chronic gastritis had significantly lower gastric concentrations of vitamin C and ascorbic acid, and ascorbic acid concentrations were especially low in subjects with hypochlorhydria. The presence of the concentration gradient suggests that a mechanism for the secretion of vitamin C into the stomach exists. This is compromised by chronic gastritis. The very low ascorbic acid concentrations in hypochlorhydria may be a consequence of oxidation by bacterial nitrite. Those patients who by the Correa model are at greatest risk for gastric cancer have the lowest gastric levels of ascorbic acid.

Diet, nutritional status, and cancer risk in American blacks

About 35% (10-70%) of all cancers may be associated with nutritional causes (1). However, while natural or added substances in foods may be carcinogenic, nutritional deficiencies or excesses may promote carcinogenesis. We compared data from blacks and whites using dietary and nutritional status surveys in the United States to determine whether the poorer dietary patterns and nutritional status of American blacks may be associated with their higher incidence and mortality from certain cancers (compared with whites). Our review indicates that blacks eat more nitrate and animal foods and not enough fiber in relation to protein, fat, and carbohydrate. Blacks also have poorer nutritional status with respect to getting enough thiamine, riboflavin, vitamins A and C, and iron, to being obese (females), and to being underweight (males). This is in agreement with hypotheses regarding the interactions between diet and cancer (associations found in whites) and dose-response relationships reported for some cancers for which blacks have a higher incidence and mortality than whites. More large-scale prospective case-control and cohort studies are needed in both blacks and whites to elucidate the contribution of specific dietary and nutritional factors to the risk of specific cancers in these population groups. However, such studies must be preceded by methodological research to obtain more valid measures of dietary and nutritional status.