Risk factors of gastric precancerous lesions in a high-risk Colombian population. I. Salt

Salt intake and gastric cancer: a pooled analysis within the Stomach cancer Pooling (StoP) Project

PURPOSE

Previous studies show that consuming foods preserved by salting increases the risk of gastric cancer, while results on the association between total salt or added salt and gastric cancer are less consistent and vary with the exposure considered. This study aimed to quantify the association between dietary salt exposure and gastric cancer, using an individual participant data meta-analysis of studies participating in the Stomach cancer Pooling (StoP) Project.

METHODS

Data from 25 studies (10,283 cases and 24,643 controls) from the StoP Project with information on salt taste preference (tasteless, normal, salty), use of table salt (never, sometimes, always), total sodium intake (tertiles of grams/day), and high-salt and salt-preserved foods intake (tertiles of grams/day) were used. A two-stage approach based on random-effects models was used to pool study-specific adjusted (sex, age, and gastric cancer risk factors) odds ratios (aORs), and the corresponding 95% confidence intervals (95% CI).

RESULTS

Gastric cancer risk was higher for salty taste preference (aOR 1.59, 95% CI 1.25-2.03), always using table salt (aOR 1.33, 95% CI 1.16-1.54), and for the highest tertile of high-salt and salt-preserved foods intake (aOR 1.24, 95% CI 1.01-1.51) vs. the lowest tertile. No significant association was observed for the highest vs. the lowest tertile of total sodium intake (aOR 1.08, 95% CI 0.82-1.43). The results obtained were consistent across anatomic sites, strata of Helicobacter pylori infection, and sociodemographic, lifestyle and study characteristics.

CONCLUSION

Salty taste preference, always using table salt, and a greater high-salt and salt-preserved foods intake increased the risk of gastric cancer, though the association was less robust with total sodium intake.

The Association between Salt and Potential Mediators of the Gastric Precancerous Process

Background: The process by which salt affects the gastric precancerous process has not been adequately studied in humans. Methods: We investigated the effects of salt on gastric inflammation, epithelial damage, the density of Helicobacter pylori infection, and gastric epithelial cell proliferation, all of which may be mediators between salt and gastric precancerous/cancerous lesions. These potential mediators were measured using gastric biopsies as: (a) the density of polymorphonuclear and mononuclear cells (gastric inflammation), (b) mucus depletion (gastric epithelial damage), and (c) the severity of H. pylori infection. Salt intake was measured with spot urine samples (using urinary sodium/creatinine ratios), self-reported frequency of adding salt to food, and as total added salt. Results: The average sodium/creatinine ratio (at baseline and post-treatment at five months) was associated with increased epithelial damage over the 12-year follow-up period among those with a greater severity of chronic inflammation and among those with continued H. pylori infection after treatment at five months. This association was stronger when both severe gastric inflammation and H. pylori infection were present at five months (ß: 1.112, 95% CI: 0.377, 1.848). Conclusion: In humans, salt was associated with an increase in epithelial damage in stomachs with more severe previous H. pylori-induced chronic inflammation.

Association between Dietary Salt Intake and Progression in the Gastric Precancerous Process

Gastric cancer is the third leading cause of cancer mortality worldwide. Studies investigating the effect of salt on gastric cancer have mainly used self-reported measures, which are not as accurate as sodium/creatinine ratios because individuals may not know the amount of salt in their food. Using data from a prospective cohort study, we investigated the effect of salt intake on progression to gastric precancerous lesions. Salt intake was estimated by urinary sodium/creatinine ratios, self-reported frequencies of adding salt to food, and total added table salt. We repeated the analyses among groups with and without Helicobacter pylori infection. We did not observe a positive association between salt intake, measured by urinary sodium/creatinine ratio, and overall progression in the gastric precancerous process (adjusted risk ratio (RR): 0.94; 95% confidence interval (CI) 0.76-1.15). We did observe an association between salt intake and increased risk for progression to dysplasia or gastric cancer overall (adjusted risk ratio (RR): 1.32; 95% confidence interval (CI): 0.96-1.81), especially among those who continued to have H. pylori infection at the five-month follow-up (adjusted RR: 1.53; 95% CI: 1.12-2.09), and among those who had persistent H. pylori infection over 12 years (adjusted RR: 1.49; 95% CI: 1.09-2.05). Salt intake may increase the risk of gastric dysplasia or gastric cancer in individuals with H. pylori infection.

Using Machine Learning to Predict Progression in the Gastric Precancerous Process in a Population from a Developing Country Who Underwent a Gastroscopy for Dyspeptic Symptoms

Background

Gastric cancer is the fourth most common cancer and the third most common cause of cancer deaths worldwide. Morbidity and mortality from gastric cancer may be decreased by identification of those that are at high risk for progression in the gastric precancerous process so that they can be monitored over time for early detection and implementation of preventive strategies.

Method

Using machine learning, we developed prediction models for gastric precancerous progression in a population from a developing country with a high rate of gastric cancer who underwent gastroscopies for dyspeptic symptoms. In the data imputed for completeness, we divided the data into a training and a validation test set. Using the training set, we used the random forest method to rank potential predictors based on their predictive importance. Using predictors identified by the random forest method, we conducted best subset linear regressions with the leave-one-out cross-validation approach to select predictors for overall progression and progression to dysplasia or cancer. We validated the models in the test set using leave-one-out cross-validation.

Results

We observed for all models that complete intestinal metaplasia and incomplete intestinal metaplasia were the strongest predictors for further progression in the precancerous process. We also observed that a diagnosis of no gastritis, superficial gastritis, or antral diffuse gastritis at baseline was a predictor of no progression in the gastric precancerous process. The sensitivities and specificities were 86% and 79% for the general model and 100% and 82% for the location-specific model, respectively.

Conclusion

We developed prediction models to identify gastroscopy patients that are more likely to progress in the gastric precancerous process, among whom routine follow-up gastroscopies can be targeted to prevent gastric cancer. Future external validation is needed.

Trends in dietary patterns, alcohol intake, tobacco smoking, and colorectal cancer in Polish population in 1960-2008

The study examined the relationships between long-term trends in food consumption, alcohol intake, tobacco smoking, and colorectal cancer (CRC) incidence. Data on CRC incidence rates were derived from the National Cancer Registry, on food consumption from the national food balance sheets; data on alcohol and tobacco smoking reflected official statistics of the Central Statistical Office. It was shown that CRC incidence rates were increasing between 1960 and 1995, which could have been affected by adverse dietary patterns (growing consumption of edible fats, especially animal fats, sugar, red meat, and declining fibre and folate intake), high alcohol consumption, and frequent tobacco smoking noted until the end of the 1980s. Since 1990, the dietary pattern changed favourably (decrease in consumption of red meat, animal fats, and sugar, higher vitamin D intake, increase in vegetables and fruit quantities consumed, and decline in tobacco smoking). These changes could contribute to the stabilisation of CRC incidence among women seen after 1996 and a reduction in the rate of increase among men.

Diet, microbial virulence, and Helicobacter pylori-induced gastric cancer

Gastric adenocarcinoma is a leading cause of cancer-related death worldwide, and Helicobacter pylori infection is one of the strongest known risk factors for this malignancy. H. pylori strains exhibit a high level of genetic diversity, and the risk of gastric cancer is higher in persons carrying certain strain types (for example, those that contain a cag pathogenicity island or type s1 vacA alleles) than in persons carrying other strain types. Additional risk factors for gastric cancer include specific human genetic polymorphisms and specific dietary preferences (for example, a high-salt diet or a diet deficient in fruits and vegetables). Finally, iron-deficiency anemia is a risk factor for gastric cancer. Recent studies have provided evidence that several dietary risk factors for gastric cancer directly impact H. pylori virulence. In this review article, we discuss mechanisms by which diet can modulate H. pylori virulence and thereby influence gastric cancer risk.

Processed meat consumption and risk of cancer: a multisite case-control study in Uruguay

BACKGROUND

The role of processed meat in the aetiology of several cancers was explored in detail.

METHODS

In the time period 1996-2004, a multisite case-control study was conducted in Montevideo, Uruguay. The study included 6 060 participants (3 528 cases and 2 532 controls) corresponding to cancers of the oral cavity, pharynx, oesophagus, stomach, colon, rectum, larynx, lung, female breast, prostate, urinary bladder, and kidney (renal cell carcinoma only).

RESULTS

The highest odds ratios (ORs) were positively associated with cancers of the colon, rectum, stomach, oesophagus, and lung. With the exception of renal cell carcinoma, the remaining cancer sites were significantly associated with elevated risks for processed meat consumption. Furthermore, mortadella, salami, hot dog, ham, and salted meat were strongly associated with risk of several cancer sites.

CONCLUSION

It could be concluded that processed meat intake could be a powerful multiorgan carcinogen.

Association between Habitual Dietary Salt Intake and Risk of Gastric Cancer: A Systematic Review of Observational Studies

Purpose. Systematic reviews of case-control and prospective studies showed a positive association between habitual salt intake and gastric cancer. Given new studies published thereafter, we carried out a meta-analysis to assess the association between dietary salt intake and gastric cancer. Methods. Case-control studies and cohort studies published between January 1992 and January 2012 on PubMed and Embase were searched. We quantified associations between salt intake and gastric cancer with meta-analysis. Results. Eleven studies (7 case controls and 4 cohorts) finally were included in the meta-analysis (total population: n = 2076498; events: n = 12039). The combined odds ratio showed significantly positive association between high salt intake and gastric cancer compared with low salt intake (OR = 2.05, 95% CI [1.60, 2.62]; P < 0.00001). In subgroup meta-analysis, findings were slightly different when analyses were restricted to salty food intake (OR = 2.41, 95% CI [2.08, 2.78]; P < 0.00001) as well as in Asia (OR = 1.27 95% CI [1.22, 1.32]; P < 0.00001). There was no evidence that sample size, exposure assessment substantially influenced the estimate of effects. Conclusions. The systemic review supports the hypothesis that dietary salt intake is positively associated with the risk of gastric cancer.

A novel model might predict the risk of chronic atrophic gastritis: a multicenter prospective study in China

OBJECTIVE

To find a new way to predict the risk of chronic atrophic gastritis (CAG).

MATERIAL AND METHODS

All the participants received endoscopy and histological examination as well as a standard questionnaire. Multivariate analysis was performed by logistic regression to build the CAG risk model. The accuracy was evaluated by 1418 subjects recruited from six medical centers. 63 subjects received another endoscopy after 1-year follow-up and divided into three groups according to the comparison of the histological results (improved, no change and worse).

RESULTS

The model showed relatively good discrimination, with an AUROC of 0.888 (95% CI 0.852-0.925). A final probability cut-off score of 0.73 was used to predict the presence (>0.73) or absence of CAG (≤0.73). Sensitivity, specificity, PPV and NPV were 82.8%, 74.7%, 91.8% and 56%, respectively. The predicted results of 1418 subjects compared with the histological results were quite similar. There was a significant difference of the scores between three groups who were followed-up for 1 year (F = 3.248, p = 0.046). In multiple comparisons, a significant difference existed between Group A (the histological results had improved after 1-year follow-up) and Group C (the results were worse) (p = 0.019).

CONCLUSIONS

This is the first demonstration of the use of a mathematical model for CAG risk screening. Endoscopy should be recommended to those who are positive according to the model, to detect CAG early and conserve medical resources. In those who have a high-risk score, closer follow-up is needed.

Salt intake and gastric cancer risk according to Helicobacter pylori infection, smoking, tumour site and histological type

BACKGROUND

Although salt intake is considered a probable risk factor for gastric cancer, relevant studies have provided heterogeneous results, and the magnitude of the association has not been accurately quantified.

METHODS

To quantify gastric cancer risk in relation to dietary salt exposure according to Helicobacter pylori infection status and virulence, smoking, tumour site, and histological type, we evaluated 422 gastric cancer cases and 649 community controls. Salt exposure was estimated in the year before the onset of symptoms through: sodium intake (estimated by a food frequency questionnaire (FFQ)); main food items/groups contributing to dietary sodium intake; visual analogical scale for salt intake preference; use of table salt; and duration of refrigerator ownership.

RESULTS

Comparing subjects with the highest with those with the lowest salt exposure (3rd vs 1st third), sodium intake (OR=2.01, 95% CI: 1.16-3.46), consumption of food items with high contribution to sodium intake (OR=2.54, 95% CI: 1.56-4.14) and salt intake evaluated by visual analogical scale (OR=1.83, 95% CI: 1.28-2.63) were associated with an increased gastric cancer risk. Subjects owning a refrigerator for >50 years had a lower risk for gastric cancer (OR=0.28, 95% CI: 0.14-0.57). These associations were observed regardless of H. pylori infection status and virulence, smoking, tumour site or histological type.

CONCLUSION

Our results support the view that salt intake is an important dietary risk factor for gastric cancer, and confirms the evidence of no differences in risk according to H. pylori infection and virulence, smoking, tumour site and histological type.

Salt intake and type of intestinal metaplasia in Helicobacter pylori-infected Portuguese men

The relation between salt intake and intestinal metaplasia (IM) types and the potential interaction with H. pylori virulence are poorly understood and may contribute to further understand gastric carcinogenesis. We quantified the association between dietary salt exposure and complete, incomplete, and mixed IM, taking into account the potential effect modification according to the virulence of H. pylori infecting strains. H. pylori-infected male volunteers (n = 233) underwent an upper digestive endoscopy and completed questionnaires comprising different measures of salt exposure (main food items/groups contributing to dietary salt intake, estimated dietary sodium intake, visual analogical scale for salt intake, preference for salty/salted foods). A histological diagnosis was assigned based on the most severe lesion observed. H. pylori virulence was assessed by characterizing vacA and cagA genes. Odds ratios were estimated through age- and education-adjusted logistic regression models. The risk of IM was not significantly increased in H. pylori infected subjects with higher levels of salt consumption. The lack of association was consistent across measures of salt exposure, categories of H. pylori virulence, and types of IM. In conclusion, in this H. pylori positive population, salt intake did not increase the risk of any IM type, regardless of the virulence of the infecting strains.

Genetic predisposition to Helicobacter pylori-induced gastric precancerous conditions

Gastric cancer is the most common malignancy of the gastrointestinal tract in East Asian populations and the second most frequent cause of cancer-related mortality in the world. While previous studies have investigated the genetic factors involved in gastric carcinogenesis, there still exist relatively few studies that have investigated the genetic traits associated with the risk of gastric precancerous conditions. In this paper we will review the biology and genetic polymorphisms involved in the genesis of gastric precancerous conditions reported to date and discuss the future prospects of this field of study. The associations of gastric precancerous conditions with polymorphisms in the cytotoxin-associated gene A-related genes (e.g. PTPN11 G/A at intron 3, rs2301756), those in the genes involved in host immunity against Helicobacter pylori (H. pylori) infection (e.g. TLR4 +3725G/C, rs11536889) or polymorphisms of the genes essential for the development/ differentiation of the gastric epithelial cells (e.g. RUNX3 T/A polymorphism at intron 3, rs760805) have been reported to date. Genetic epidemiological studies of the associations between H. pylori-induced gastric precancerous conditions and other gene polymorphisms in these pathways as well as polymorphisms of the genes involved in other pathways like oxidative DNA damage repair pathways would provide useful evidence for the individualized prevention of these H. pylori-induced gastric precancerous conditions.

Salt intake and risk of gastric intestinal metaplasia: systematic review and meta-analysis

The understanding of the association between salt intake and precancerous lesions may contribute to clarify the causal relation with gastric cancer. We systematically reviewed 17 articles addressing the association between dietary salt exposure and gastric intestinal metaplasia and conducted meta-analyses for quantitative synthesis (random effects model). Salt exposure was estimated assessing salted/salty food consumption, preference for salted/salty foods, use of table salt, or sodium urinary excretion. Heterogeneity was also large regarding food items evaluated, consumption categories, and data analysis. The combined odds ratio (OR) was 1.68 (95% confidence interval (CI) = 0.98-2.90; I(2) = 55.4%) for the association between salted/salty meat and intestinal metaplasia (4 studies) and the OR was 1.53 (95% CI = 0.72-3.24; I(2) = 76.8%) for salt preference. There was a positive, nonstatistically significant association between intestinal metaplasia and urinary sodium excretion. The heterogeneity of methodological options and results preclude quantitative synthesis or its proper interpretation, even if the available evidence may suggest a positive association between salt and intestinal metaplasia.

Helicobacter pylori in health and disease

Helicobacter pylori is highly adapted for colonization of the human stomach and is present in about half of the human population. When present, H pylori is usually the numerically dominant gastric microorganism. H pylori typically does not cause any adverse effects, but it is associated with an increased risk of noncardia gastric adenocarcinoma, gastric lymphoma, and peptic ulcer. Disorders such as esophageal diseases and childhood-onset asthma were recently reported to occur more frequently in individuals who lack H pylori than in H pylori-positive persons. In this review, we discuss biologic factors that allow H pylori to colonize the human stomach, mechanisms by which H pylori increases the risk of peptic ulcer disease and noncardia gastric adenocarcinoma, and potential benefits that H pylori might confer to humans.

Natural history of Helicobacter pylori infection

This report describes the modalities of chronic gastritis induced by Helicobacter pylori infection in different populations. The full gamut of lesions representing the precancerous cascade is very prevalent in populations of low socioeconomic background experiencing very high gastric cancer risk, as seen in the Latin American Andes Mountains. In populations of high socioeconomic standards and high cancer risk, such as Japan and Korea, the precancerous cascade predominates and "early" cancers are also diagnosed frequently. Some reports describe frequent corpus atrophy, not prominent in the former group. The so-called African enigma is seen in populations of low socioeconomic standards, usually living at low altitudes, with high prevalence of infection but low frequency of cancer and precancerous lesions. In populations in transition from high to low cancer risk, duodenal ulcer and antral non-atrophic gastritis are frequently seen. In affluent societies at low risk of cancer, such as Western Europe, Australia and North America, mild non-atrophic gastritis associated with low virulence Helicobacter pylori genotypes predominate. The varied phenotypes of gastritis may reflect secular changes in the ecology of our species.

Genetic factors involved in the development of Helicobacter pylori-related gastric cancer

Developmental process to gastric cancer by Helicobacter pylori infection consists of three steps: (1) H. pylori infection; (2) gastric atrophy development; and (3) carcinogenesis. In each step, genetic traits may influence the process, interacting with lifestyle. In the step of H. pylori infection, two lines of genetic polymorphisms were assumed: one influencing gastric acid inhibition interacting with smoking, and the other concerning innate immune response attenuation. The former includes functional polymorphisms of IL-1B (C-31T or tightly linked T-511C), and TNF-A (T-1031C and C-857T), and the latter possibly includes NQO1 C609T. In the step to gastric atrophy, polymorphisms pertaining to the signal transduction from cytotoxin-associated gene A (PTPN11 A/G at intron 3) and to T-cell responses (IL-2 T-330G and IL-13 C-1111T) were hypothesized. There are a limited number of epidemiological genotype studies on the final step of literal carcinogenesis, potentially interacting with smoking, a low vegetable and fruit intake, and salty foods, the well-documented risk factors. In past case-control studies on the associations between genotype and gastric cancer risk, the cases consisted of H. pylori-related and unrelated gastric cancer patients and the controls consisted of individuals including the uninfected (H. pylori unexposed and exposed) and the infected with and without gastric atrophy. Accordingly, it was not clear whether the observed risk was for H. pylori-related or -unrelated gastric cancer, nor which step was involved in the observed associations even when nearly all cases were H. pylori-related. In order to elucidate the genetic traits of H. pylori-related gastric cancer, stepwise evaluation will be required.

The serum pepsinogen test as a predictor of gastric cancer: the Hisayama study

The authors examined whether a serum pepsinogen test (SPT) based on the combination of the serum pepsinogen I level and pepsinogen I/II ratio is a good predictor of gastric cancer occurrence in a general Japanese population. A total of 2,446 subjects aged > or =40 years were classified into negative, positive, and strong-positive SPT groups and were followed prospectively for 14 years (1988-2002). Compared with that for the negative SPT group (26 men, 10 women), gastric cancer incidence increased significantly for both men (n = 17; age-adjusted hazard ratio = 4.56, 95% confidence interval: 2.42, 8.60) and women (n = 6; age-adjusted hazard ratio = 5.84, 95% confidence interval: 2.00, 17.11) in the strong-positive SPT group. It was also significantly higher in the positive SPT group for men (n = 23; age-adjusted hazard ratio = 3.91, 95% confidence interval: 2.23, 6.86). These associations did not attenuate even after adjustment for other comprehensive risk factors. Stratified analysis revealed significant associations between the SPT and development of intestinal-type gastric cancer as well as of cancer in both Helicobacter pylori-negative and -positive subjects. These findings suggest that the SPT can serve as a predictor of intestinal-type gastric cancer, irrespective of H. pylori infection.

Food/nutrient intake and risk of atrophic gastritis among the Helicobacter pylori-infected population of northeastern Japan

Although Helicobacter pylori (H. pylori ) infection is considered a key risk factor for atrophic gastritis, along with other environmental factors, it is still unclear which factor is involved in the development of atrophic gastritis among H. pylori-infected subjects. In the present cross-sectional study, therefore, we analyzed various dietary factors in relation to the presence of atrophic gastritis among H. pylori-infected subjects who participated in a health check-up program in a town in northeastern Japan. One thousand and seventy-one subjects (362 males and 709 females) who provided both self-administered validated food frequency questionnaires and blood samples were the basis for the study, and all of them were serologically positive for H. pylori immunoglobulin G (IgG) antibody. Among them, 663 (223 males and 440 females) were diagnosed as having atrophic gastritis on the basis of serum pepsinogen levels. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated based on tertile categories of subjects without atrophic gastritis, using logistic regression analysis. Among females, high consumptions of rice (OR = 1.6, 95% CI: 1.1-2.3), cod roe (OR = 1.5, 95% CI: 1.0-2.2) and cuttlefish (OR = 1.5, 95% CI: 1.0-2.3) were associated with a moderately increased risk of atrophic gastritis after adjustment for age (P for trend = 0.02 for these items). Among males, high consumptions of rice and miso soup showed a tendency toward an increased risk (P for trend = 0.12 and 0.13, respectively). Vegetables and fruits showed no association among either males or females. From these results, it is suggested that the dietary habits of consumers of traditional Japanese foods may play a role in the development of atrophic gastritis after H. pylori infection.

Histological patterns of gastritis in H. pylori-infected individuals with a family history of gastric cancer

OBJECTIVE

Different types of chronic gastritis, including antral predominant, corpus predominant, and multifocal pangastritis, are associated with Helicobacter pylori infection. Specific patterns of H. pylori gastritis that might characterize individuals with family histories of noncardia gastric cancer (GC) were investigated.

METHODS

Histopathological changes associated with H. pylori gastritis were assessed in 111 individuals with family histories of GC and in 77 without from a region with high prevalence of H. pylori infection and GC. Gastric biopsies were taken from 12 sites (antrum, five; corpus, six; and cardia, one).

RESULTS

Individuals (age < 36 yr) with family histories of GC developed pangastritis and had higher H. pylori bacterial scores (p < 0.05) in the gastric corpus, whereas those without family histories of GC typically had antral predominant gastritis. The correlation between density of polymorphonuclear leukocytes and density of H. pylori at each biopsy site was statistically significant (p < 0.01). Pangastritis was associated with a higher density of lymphoid aggregates and follicles (p < 0.05) in the corpus of younger individuals (age < 36) and in the antrum of older individuals (age > or = 48) with positive family histories of GC.

CONCLUSIONS

Pangastritis and high lymphoid follicle density associated with H. pylori infection were found in patients with family histories of GC. Because a family history of gastric carcinoma is associated with increased risk of gastric cancer development, characterization of histological patterns of gastritis may be applicable to gastric cancer screening and surveillance, especially in relatively young at-risk populations.

Phospholipase C delta2 expression characterizes the neoplastic transformation of the human gastric mucosa

The expression, cellular distribution, and activity of PIP(2)-specific phospholipase C (PLC) in healthy human gastric-mucosa cells have been recently studied in our laboratories and a direct evidence for an almost exclusive expression of PLC beta isoforms, with the exception of PLC beta4, has been provided. These results addressed our attention to possible modification of PLC expression and activity during neoplastic transformation of the human gastric mucosa. In the present article we present results indicating that PLC delta2 is markedly expressed in type II intestinal metaplasia and in the adenocarcinoma whereas traces of other PLC isoforms were sometime detected. Interestingly, we found that type I intestinal metaplasia was in the majority of the cases PLC delta2-negative, but when expressed, this type of metaplasia generally considered as benignant, always evolved toward neoplastic transformation. These results therefore readdress the question of surveillance of the patients with type I intestinal metaplasia and suggest that PLC delta2 expression might be a possible marker of gastric malignant transformation.

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.

Inability to noninvasively diagnose gastric intestinal metaplasia in Hispanics or reverse the lesion with Helicobacter pylori eradication

BACKGROUND

Helicobacter pylori infection has been linked with the development of gastric adenocarcinoma and its precursor lesion, intestinal metaplasia (IM). The presence of gastric IM is not associated with symptoms, which makes identification of individuals with this lesion difficult. It is not clear whether eradication of H. pylori infection leads to reversal of gastric IM or the potential decrease in the risk of cancer in these patients.

GOALS

The purpose of this pilot study was to define the prevalence of gastric IM in a population at high risk for gastric cancer (Southwestern Hispanics), examine the ability of noninvasive testing to identify individuals with the lesion, and determine whether eradication of H. pylori infection reverses gastric IM in this population.

STUDY

Subjects from the Tucson metropolitan area were recruited, and baseline data, including the presence of upper gastrointestinal (UGI) symptoms, urinary sodium, and serum pepsinogen levels, were obtained. Upper endoscopy was performed and six gastric biopsies from specific anatomic sites were obtained, followed by methylene blue staining with targeted biopsies from blue-stained mucosa. Biopsies were evaluated for the presence of H. pylori infection and gastric IM. A subset of patients with gastric IM were treated to eradicate H. pylori infection. Follow-up exams with methylene blue staining, including biopsies for histology and rapid urease testing, were performed for up to 48 months.

RESULTS

There were 84 subjects with a mean age of 53.0 years; 24 (29%) had gastric IM and 65 (77%) had H. pylori. There was no significant association between gastric IM and age, gender, UGI symptoms, H. pylori, or urine sodium. There was an association identified between gastric IM and a decreased pepsinogen I:II ratio (p = 0.03). Of the 11 individuals with gastric IM treated for H. pylori infection, 9 had successful therapy and underwent at least 2 follow-up examinations. The mean length of follow-up was 3.3 years. Eight of the nine (89%) had gastric IM identified histologically at the final endoscopic exam.

CONCLUSIONS

H. pylori infection and gastric IM are frequent findings in Southwestern Hispanics, a high-risk population for gastric cancer. Noninvasive testing is not clinically useful in distinguishing individuals within this group who harbor gastric IM. Although eradication of H. pylori infection may lead to a decrease in the amount of gastric IM in some individuals, the lesion may be detected in the majority of individuals after more than 3 years of follow-up. These data suggest that therapy for H. pylori may not eliminate the risk of gastric cancer once IM has developed.

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.

Gastric dysplasia: the Padova international classification

A worldwide-accepted histologic, classification of the gastric carcinomatous and precancerous lesions is a prerequisite for a consistent recording of epidemiologic data and for both developing and evaluating primary and secondary preventive efforts. Different nomenclatures have been proposed for gastric precancerous lesions in eastern countries and in Japan. This article presents a classification of gastric precancerous lesions resulting from an international consensus conference involving pathologists of different countries. Five main diagnostic categories are identified. To allow comparisons with the nomenclature proposed by the Japanese Research Society for Gastric Cancer, each category was also assigned a numeric identification: 1 = normal, 2 = indefinite for dysplasia, 3 = noninvasive neoplasia, 4 = suspicious for invasive cancer, and 5 = cancer. The interobserver reproducibility of the histologic classification was tested in a series of 46 cases. By collapsing benign alterations (categories 1+2) versus noninvasive neoplasia (category 3) versus suspicious for invasive cancer and fully appearing carcinomatous lesions (categories 4+5), the general agreement value was 77.7%, whereas kappa coefficient was 0.63. By examining gastric precancerous lesions from diverse populations, the authors agreed that the gastric precancerous process is universal and the differences in nomenclatures are merely semantics. The international Padova classification of the gastric precancerous lesions is submitted to the attention of the international scientific community, which is invited to test and to improve on it.

Gastric cancer distal to the cardia--prevention or cure?

Adenocarcinoma of the stomach distal to the cardia remains one of the most common cancers in the world. The interest in the aetiology of this disease has been rekindled because of recent epidemiological and molecular studies linking this cancer to H. pylori and certain dietary factors. The authors provide an updated review of the aetiology of gastric cancer. This review seeks to summarize the disease, to propose pathways of carcinogenesis and to suggest ways in which the "traditional" risk factors may be interpreted on the basis of evolving knowledge.

Evaluation of the aetiological role of dietary salt exposure in gastric and other cancers in humans

The findings in laboratory and epidemiological studies relevant to the assessment of salt for carcinogenic potential are reviewed. Associations between the high consumption of certain highly salted foodstuffs, particularly in some oriental countries, and increased risk of cancer of the stomach do not incriminate salt per se. Some highly spiced foods contain potent genotoxic carcinogens, irrespective of whether they also contain salt. There is evidence in laboratory animals that high concentrations of salt may increase the incidence of gastric cancer caused by such carcinogens. This may well be attributable to a marked and sustained regenerative response in the gastric mucosa of laboratory animals chronically exposed to the cytotoxicity of hyperosmolar concentrations of salt, such a mitogenic response favouring the progression towards neoplasia. However, there is no laboratory evidence whatsoever to indicate that salt per se is a carcinogen for any site in the body; neither is there any reliable epidemiological evidence to indicate that dietary salt affects the incidence of gastric or other cancers. A particular problem in the interpretation of epidemiological studies is that the consumption of diets containing highly salted, spicy foods is often associated with low intakes of fruit and green vegetables, which contain cancer-protective antioxidants. In Western countries the incidence of cancer of the stomach has been falling for some 50 years. The consensus view is that this fall is attributable to improved food hygiene and increasingly available facilities for refrigeration. There are no grounds for supposing that the fall is attributable to a decreasing intake of salt. A high dietary salt intake does not necessarily entail exposure to salt in concentrations high enough to damage the gastric mucosa. The typical Western diet would not be expected to provide such high salt concentrations. It is concluded that there are no grounds for believing that a reduction in the average daily salt intake in the Western diet would have any effect on the risk of developing any form of cancer.

Proliferative activity of gastric epithelium in progressive stages of Helicobacter pylori infection

Helicobacter pylori (HP) infection is the main etiopathogenetic agent responsible for inflammatory and ulcerative changes in gastroduodenal mucosa and the basis for both intestinal and diffuse types of gastric carcinoma. In this latter case, intestinal metaplasia is the intermediary between gastritis and cancer. In this study we describe the proliferative activity of gastric epithelium in the progressive stages of HP infection. The expression of proliferating cell nuclear antigen (PCNA), which has proven to be a reliable method for this evaluation, was used as a marker. The study was performed on endoscopic biopsies of the gastric antrum of 40 patients, who were divided into five groups, eight in each group: normal histology and endoscopy, HP-; histological HP+ gastritis with normal endoscopy; histological HP+ gastritis with endoscopic evidence of chronic erosions; complete and incomplete intestinal metaplasia in a HP+ stomach. PCNA was detected by immunohistochemistry and expressed as labeling index, ie, percentage of positive nuclei either in the whole or upper third of foveolae. Our data show a progressive increase of epithelial proliferation in the successive stages of HP infection ranging from gastritis alone to the development of incomplete intestinal metaplasia, a well-known precancerous condition. The proliferative pattern tended to expand towards the upper foveolar third, which in normal conditions does not represent a site of epithelial renewal. These alterations may be related to the development of neoplastic transformations of gastric epithelium. It is well known that genetic mutations are facilitated in proliferating cells. Therefore, our results indicate that the high epithelial turnover, expressed by PCNA LI, may be an indicator of increased risk of neoplastic changes in long-standing untreated HP+ chronic gastritis.

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.

Gastric carcinogenesis in rats given hypertonic salt at different times before a single dose of N-methyl-N'-nitro-N-nitrosoguanidine

A 1-ml dose of 4.5 M NaCl was given intragastrically to male Wistar rats at 10 min, 1 h, 4 h, 12 h, 24 h or 48 h before a single intragastric dose of 250 mg/kg N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). After 52 weeks the incidence of forestomach squamous cell carcinoma was 21% in control animals receiving MNNG alone. The cancer incidence in the forestomach varied with the time elapsed between application of NaCl and MNNG, and was significantly increased in animals pretreated with NaCl 4 h (43%), 12 h (54%) and 24 h (41%) before MNNG. These results show that salt has a cocarcinogenic effect on initiation of forestomach carcinogenesis in rats, and that this effect depends on the time interval between pretreatment with NaCl and application of MNNG. Gastric adenocarcinomas occurred more frequently in the antrum (78%) than in the corpus (22%). The incidence of gastric adenocarcinoma in animals pretreated with salt before application of MNNG (11%-22%) was not significantly influenced by the time elapsed between pretreatment with salt and application of MNNG, and did not differ from animals receiving MNNG alone (18%). The lack of a cocarcinogenic effect of NaCl on glandular gastric carcinogenesis might be due to the use of dimethyl/sulfoxide as solvent for MNNG.

Diet, Helicobacter pylori infection, food preservation and gastric cancer risk: are there new roles for preventative factors?

Risks for gastric cancer in relation to diet and other environmental factors are receiving renewed attention. New developments include the emerging relationship between Helicobacter pylori infection and an increased risk for gastric cancer, and positive results of chemoprevention trials in decreasing gastric cancer risk with the use of beta-carotene and vitamin E supplements. Factors that may enhance risk include consumption of nitrites, nitrates, alcohol, and highly salted, pickled, fermented, or smoked foods. Other environmental factors which may promote cancer are H. pylori infection, inappropriate food storage, metal and cement dust exposure, and cigarette smoking. High intakes of fruits and vegetables or of antioxidants, such as beta-carotene, vitamin E, and vitamin C may decrease risk.

A cohort study of stomach cancer in a high-risk American population

Demographic, smoking and dietary information was obtained from a cohort of 17,633 white American men, largely of Scandinavian and German descent, who responded to a mailed questionnaire in 1966. After 20 years of follow-up, 50% to 90% increases in mortality from stomach cancer (75 deaths) were found among foreign-born, their children, and among residents of the North Central states. An association was seen with low educational attainment and laboring or semiskilled occupations, primarily among immigrants and their children. Risk was evaluated in subjects who regularly smoked cigarettes (RR = 2.6, 95% CI = 1.1 to 5.8). A significant dose-response trend was observed, with subjects who smoked 30 or more cigarettes per day having more than a five-fold increased risk compared with those who never smoked. Elevated risks were also found for pipe smoking and smokeless tobacco use, but not for alcohol consumption. Analysis of dietary consumption of nine food groups revealed no significant associations with stomach cancer. However, total carbohydrate intake and a few individual food items (salted fish, bacon, cooked cereal, milk, and apples) were associated with increased risk. The findings of this prospective study of a high-risk population add to the limited evidence relating tobacco consumption to stomach cancer risk and suggest clues to ethnic, geographic, and dietary risk factors.

Urinary salt excretion and stomach cancer mortality among four Japanese populations

A relationship between salt intake and the occurrence of stomach cancer has been suggested by both epidemiologic and experimental data. To test this hypothesis, urinary excretion of salt in 24 hours and dietary intake of salt were measured in four male populations with different levels of stomach cancer mortality. Age-adjusted mortality rate of stomach cancer showed a high correlation (r2 = 0.995) with the average amount of salt excretion in 24-hour urine. This strong correlation, however, was not shown (r2 = 0.265) with dietary salt intake calculated from the standard food-composition table. The results confirmed the important role of salt in the development of stomach cancer in Japan, and raised the problem of evaluating the level of salt intake by using the uniform composition table.

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.

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.