Urinary salt excretion and stomach cancer mortality among four Japanese populations

Inflammation and Gastric Cancer

Gastric cancer remains a major killer globally, although its incidence has declined over the past century. It is the fifth most common cancer and the third most common reason for cancer-related deaths worldwide. Gastric cancer is the outcome of a complex interaction between environmental, host genetic, and microbial factors. There is significant evidence supporting the association between chronic inflammation and the onset of cancer. This association is particularly robust for gastrointestinal cancers in which microbial pathogens are responsible for the chronic inflammation that can be a triggering factor for the onset of those cancers. Helicobacter pylori is the most prominent example since it is the most widespread infection, affecting nearly half of the world’s population. It is well-known to be responsible for inducing chronic gastric inflammation progressing to atrophy, metaplasia, dysplasia, and eventually, gastric cancer. This review provides an overview of the association of the factors playing a role in chronic inflammation; the bacterial characteristics which are responsible for the colonization, persistence in the stomach, and triggering of inflammation; the microbiome involved in the chronic inflammation process; and the host factors that have a role in determining whether gastritis progresses to gastric cancer. Understanding these interconnections may improve our ability to prevent gastric cancer development and enhance our understanding of existing cases.

Geospatial Assessments of DNA Adducts in the Human Stomach: A Model of Field Cancerization

BACKGROUND

Field cancerization is a popular concept regarding where cancer cells arise in a plane, such as the opened-up gastrointestinal mucosa. The geospatial distribution of DNA adducts, some of which are believed to initiate mutation, may be a clue to understanding the landscape of the preferred occurrence of gastric cancer in the human stomach, such that the occurrence is much more frequent in the lesser curvature than in the greater curvature.

METHODS

Seven DNA adducts, C5-methyl-2'-deoxycytidine, 2'-deoxyinosine, C5-hydroxymethyl-2'-deoxycytidine, N6-methyl-2'-deoxyadenosine, 1,N6-etheno-2'-deoxyadenosine, N6-hydroxymethyl-2'-deoxyadenosine, and C8-oxo-2'-deoxyguanosine, from different points and zones of the human stomach were semi quantitatively measured by liquid chromatography/tandem mass spectrometry. The differences in the quantity of these DNA adducts from the lesser and greater curvature, the upper, middle and lower third zones, the anterior and posterior wall of the stomach, and the mucosae distant from and near the tumor were compared to determine whether the location preference of cancer in the stomach could be explained by the distribution of these DNA adducts. Comparisons were conducted considering the tumor locations and operation methods.

CONCLUSIONS

Regarding the DNA adducts investigated, significant differences in quantities and locations in the whole stomach were not noted; thus, these DNA adducts do not explain the preferential occurrence of cancer in particular locations of the human stomach.

Natural Products: Implication in Cancer Prevention and Treatment through Modulating Various Biological Activities

Cancer is one of the most leading causes of death worldwide. It is one of the primary global diseases that cause morbidity and mortality in millions of people. It is usually caused by different carcinogenic agents that damage the genetic material and alter the cell signaling pathways. Carcinogens are classified into two groups as genotoxic and non-genotoxic agents. Genotoxic carcinogens are capable of directly altering the genetic material, while the non-genotoxic carcinogens are capable of producing cancer by some secondary mechanisms not related to direct gene damage. There is undoubtedly the greatest need to utilize some novel natural products as anticancer agents, as these are within reach everywhere. Interventions by some natural products aimed at decreasing the levels and conditions of these risk factors can reduce the frequency of cancer incidences. Cancer is conventionally treated by surgery, radiation therapy and chemotherapy, but such treatments may be fast-acting and causes adverse effects on normal tissues. Alternative and innovative methods of cancer treatment with the least side effects and improved efficiency are being encouraged. In this review, we discuss the different risk factors of cancer development, conventional and innovative strategies of its management and provide a brief review of the most recognized natural products used as anticancer agents globally.

Reported Amount of Salt Added to Food Is Associated with Increased All-Cause and Cancer-Related Mortality in Older Men in a Prospective Cohort Study

BACKGROUND

The effect of dietary salt intake on important population outcomes such as mortality is controversial. The aim of this study was to examine the association between the dietary habit of adding salt to food and mortality in older men. Design, participants, setting and measurements: A risk factor questionnaire which contained a question about the dietary habit of adding salt to food was completed by 11742 community recruited older men between 1996 and 1999. The men were followed by means of the Western Australia Data Linkage System until November 30th 2010. Deaths due to cardiovascular diseases and cancers were identified using ICD-10 codes in the ranges I00-I99 and C00-D48, respectively. The association between the frequencies of adding salt to food and mortality was assessed using Kaplan Meier estimates and Cox proportional hazard analysis.

RESULTS

Median follow-up for survivors was 12.5 years (inter-quartile range 8.3-13.2 years). A total of 5399 deaths occurred of which the primary cause registered was cancer and cardiovascular disease in 1962 (36.3%) and 1835 (34.0%) men, respectively. The reported frequency of adding salt to food was strongly positively associated with all-cause (p<0.001), cancer-related (p<0.001) but not cardiovascular-related (p=0.649) mortality. Men reporting adding salt to their food always had a 1.12-fold (95% CI 1.05-1.20, p<0.001) and a 1.20-fold (95% CI 1.07-1.34, p=0.001) increased risk of all-cause and cancer-related mortality, respectively, after adjusting for other risk factors. Men reporting adding salt to their food sometimes had a 1.16-fold (95% CI 1.04-1.29, p=0.007) increased risk of cancer-related mortality after adjusting for other risk factors.

CONCLUSION

A history of adding salt to food is associated with increased cancer-related mortality in older men.

Dietary factors modulate Helicobacter-associated gastric cancer in rodent models

Since its discovery in 1982, the global importance of Helicobacter pylori-induced disease, particularly in developing countries, remains high. The use of rodent models, particularly mice, and the unanticipated usefulness of the gerbil to study H. pylori pathogenesis have been used extensively to study the interactions of the host, the pathogen, and the environmental conditions influencing the outcome of persistent H. pylori infection. Dietary factors in humans are increasingly recognized as being important factors in modulating progression and severity of H. pylori-induced gastric cancer. Studies using rodent models to verify and help explain mechanisms whereby various dietary ingredients impact disease outcome should continue to be extremely productive.

Self-reported taste preference can be a proxy for daily sodium intake in middle-aged Japanese adults

Reducing dietary salt intake remains a challenging issue in the management of chronic disease. Taste preference is suspected to be an important proxy index of daily sodium consumption. This study examined the difference in daily sodium intake according to self-reported taste preference for miso soup as representative of homemade cooking in middle-aged urban Japanese adults. Among 896 candidates randomly selected from examinees of cancer screening provided by the National Cancer Center, Japan, 143 men and women participated in this cross-sectional study. During the period from May 2007 through April 2008, participants provided a food frequency questionnaire, which included information on taste preference and dietary behaviors, a weighed food record over 4 consecutive days, a simultaneous 24-hour urine collection, and a sample of miso soup as it is usually prepared in the home. Mean 24-hour urinary sodium excretion and daily sodium intake were compared according to the self-reported taste preference for miso soup. Taste preference was significantly associated with both 24-hour urinary sodium excretion (trend P<0.01) and daily sodium intake (trend P=0.01), with a corresponding regression coefficient per 1 rank preference increment of 403 mg and 315 mg/day, respectively. The observed association between preference and urinary excretion was attenuated by further adjustment for discretionary salt-related behaviors. These findings suggest that self-reported taste preference for homemade cooking is a defining feature of daily sodium intake through discretionary salt-related dietary behaviors. A reduction in daily sodium consumption per 1 rank light preference was estimated to equate to approximately 1 g salt/day.

Up-regulation of neutrophil activating protein in Helicobacter pylori under high-salt stress: structural and phylogenetic comparison with bacterial iron-binding ferritins

It is generally accepted that most gastrointestinal diseases are probably caused by the bacterial pathogen Helicobacter pylori (H. pylori). In this study we have focused on the comparison of protein expression profiles of H. pylori grown under normal and high-salt conditions by a proteomics approach. We have identified about 190 proteins whose expression levels changed after growth at high salt concentration. Among these proteins, neutrophil-activating protein (NapA) was found to be consistently up-regulated under osmotic stress brought by high salts. We have investigated the effect of high salt on secondary and tertiary structures of NapA by circular dichroism spectroscopy followed by analytical ultracentrifugation to monitor the change of quaternary structure of recombinant NapA with increasing salt concentration. The loss of iron-binding activity of NapA coupled with noticeable energetic variation in protein association of NapA as revealed by isothermal titration calorimetry was found under high salt condition. The phylogenetic tree analysis based on sequence comparison of 16 protein sequences encompassing NapA proteins and ferritin of H. pylori and other prokaryotic organisms pointed to the fact that all H. pylori NapA proteins of human origin are more homologous to NapA of Helicobacter genus than to other bacterial NapA. Based on computer modeling, NapA proteins from H. pylori of human isolates are found more similar to ferritin from H. pylori than to NapA from other species of bacteria. Taken together, these results suggested that divergent evolution of NapA and ferritin possessing dissimilar and diverse sequences follows a path distinct from that of convergent evolution of NapA and ferritin with similar dual functionality of iron-binding and ferroxidase activities.

Ecological study for refrigerator use, salt, vegetable, and fruit intakes, and gastric cancer

We used an ecological approach to determine the correlation between vegetable, fruit and salt intakes, refrigerator use, and gastric cancer mortality in Korean population. Information on fruit and vegetable intakes per capita from the National Health and Nutrition Survey, death certificate data from the National Statistical office, refrigerator per household data from Korean Statistical Information Service, and salt/sodium intake data from a cross-sectional survey were utilized. Correlation coefficients were calculated between vegetable and fruit intakes, refrigerator per household, and gastric cancer mortality and between salt and sodium intakes, and gastric cancer mortality and incidence in the four areas. With 5, 10, and 15 years lag time, refrigerator usage and fruit intake were negatively associated with gastric cancer mortality (p < 0.01), but vegetable intake was not associated with gastric cancer mortality. When estimates of salt/sodium intake evaluated by 24-h urine collection in four areas of Korea were compared to the gastric cancer mortality and incidence in these regions, positive correlation was shown between salt/sodium intake, and gastric cancer incidence and mortality. Negative associations between refrigerator use, fruit intake, and gastric cancer mortality and positive associations between salt/sodium intake and gastric cancer mortality and incidence were suggested.

Fermented and non-fermented soy food consumption and gastric cancer in Japanese and Korean populations: a meta-analysis of observational studies

Soy food is known to contribute greatly to a reduction in the risk of gastric cancer (GC). However, both Japanese and Korean populations have high incidence rates of GC despite the consumption of a wide variety of soy foods. One primary reason is that they consume fermented rather than non-fermented soy foods. In order to assess the varying effects of fermented and non-fermented soy intake on GC risk in these populations, we conducted a meta-analysis of published reports. Twenty studies assessing the effect of the consumption of fermented soy food on GC risk were included, and 17 studies assessing the effect of the consumption of non-fermented soy food on GC risk were included. We found that a high intake of fermented soy foods was significantly associated with an increased risk of GC (odds ratio [OR] = 1.22, 95% confidence interval [CI] = 1.02-1.44, I(2) = 71.48), whereas an increased intake of non-fermented soy foods was significantly associated with a decreased risk of GC (overall summary OR = 0.64, 95% CI = 0.54-0.77, I(2) = 64.27). These findings show that a high level of consumption of non-fermented soy foods, rather than fermented soy foods, is important in reducing GC risk.

Fresh and pickled vegetable consumption and gastric cancer in Japanese and Korean populations: a meta-analysis of observational studies

It is widely known that vegetable consumption contributes to reducing the risk of gastric cancer (GC). However, the incidence rates of GC remain high in both Japanese and Korean populations, even though they have a high consumption of total vegetables. This may be due to the fact that Japanese and Koreans mainly consume processed vegetables, such as cooked, salted, or pickled vegetables, rather than fresh vegetables. To determine whether the intakes of fresh and pickled vegetables have different effects on the risk of GC in Japanese and Korean populations, we carried out a meta-analysis of published epidemiological reports. Eight studies on the consumption of fresh vegetables and 14 studies on the consumption of pickled vegetables related to GC risk were included in this meta-analysis. Four studies exploring differences in GC risk in men and women were considered separately. We observed that a high intake of fresh vegetables was significantly associated with a decreased risk of GC (overall summary OR = 0.62, 95% CI = 0.46-0.85) but that a high intake of pickled vegetables was significantly associated with an increased risk of GC (overall summary OR = 1.28, 95% CI = 1.06-1.53). The results of this meta-analysis provide evidence that a high intake of pickled vegetables may increase GC risk and suggest that a high consumption of fresh vegetables, rather than a large total amount of vegetables including pickled vegetables, is important to reduce GC risk.

Consumption of sodium and salted foods in relation to cancer and cardiovascular disease: the Japan Public Health Center-based Prospective Study

BACKGROUND

Although the influence of salt, per se, on the risk of cancer or cardiovascular disease (CVD) might differ from that of salt-preserved foods, few studies have simultaneously examined the effects of sodium and salted foods on the risk of either cancer or CVD.

OBJECTIVE

We simultaneously examined associations between sodium and salted food consumption and the risk of cancer and CVD.

DESIGN

During 1995-1998, a validated food-frequency questionnaire was administered to 77,500 men and women aged 45-74 y. During up to 598,763 person-years of follow-up until the end of 2004, 4476 cases of cancer and 2066 cases of CVD were identified.

RESULTS

Higher consumption of sodium was associated with a higher risk of CVD but not with the risk of total cancer: multivariate hazard ratios for the highest compared with lowest quintiles of intake were 1.19 (95% CI: 1.01, 1.40; P for trend: 0.06) for CVD and 1.04 (95% CI: 0.93, 1.16; P for trend: 0.63) for total cancer. Higher consumption of salted fish roe was associated with higher risk of total cancer, and higher consumption of cooking and table salt was associated with higher risk of CVD. Similar results were seen for the risk of gastric or colorectal cancer and stroke.

CONCLUSIONS

Sodium intake as a whole salt equivalent may not increase the risk of cancer but may increase that of CVD. In contrast, salted food intake may increase the risk of cancer. Our findings support the notion that sodium and salted foods have differential influences on the development of cancer and CVD.

Review of salt consumption and stomach cancer risk: epidemiological and biological evidence

Stomach cancer is still the fourth most common cancer; thus, it remains an important public health burden worldwide, especially in developing countries. The remarkable geographic variations in the rates of stomach cancer indicate that dietary factors, including a range of food groups to which salt and/or nitrates have been added, may affect stomach cancer risk. In this paper, we review the results from ecologic, case-control and cohort studies on the relationship between salt or salted foods and stomach cancer risk. The majority of ecological studies indicated that the average salt intake in each population was closely correlated with gastric cancer mortality. Most case-control studies showed similar results, indicating a moderate to high increase in risk for the highest level of salt or salted food consumption. The overall results from cohort studies are not totally consistent, but are suggestive of a moderate direct association. Since salt intake has been correlated with Helicobacter pylori (H pylori) infection, it is possible that these two factors may synergize to promote the development of stomach cancer. Additionally, salt may also cause stomach cancer through directly damaging gastric mucus, improving temporary epithelial proliferation and the incidence of endogenous mutations, and inducing hypergastrinemia that leads to eventual parietal cell loss and progression to gastric cancer. Based on the considerable evidence from ecological, case-control and cohort studies worldwide and the mechanistic plausibility, limitation on salt and salted food consumption is a practical strategy for preventing gastric cancer.

New and traditional smokeless tobacco: comparison of toxicant and carcinogen levels

Declining cigarette use and spreading bans on smoking in public places in the United States are encouraging the U.S. cigarette industry to turn to another tobacco category, smokeless tobacco products. Currently, a number of new brands are being test marketed, including Taboka, Marlboro Snus, Camel Snus, and Skoal Dry. We report here levels of tobacco-specific nitrosamines (TSNAs), alkaloids, anions, polycyclic aromatic hydrocarbons (PAH), and volatile aldehydes in these products, and compare them to the most popular traditional moist snuff brands. Total TSNAs averaged 1.97 microg/g dry weight tobacco in Taboka, Marlboro Snus, and Camel Snus, 4.54 microg/g tobacco in Skoal Dry, and 7.42 microg/g tobacco in traditional brands. The amounts of unprotonated nicotine averaged 0.961 mg/g tobacco in Taboka, Marlboro Snus, and Skoal Dry, 7.22 mg/g tobacco in Camel Snus, and 7.57 mg/g tobacco in traditional brands. Levels of minor tobacco alkaloids were relatively high in Taboka, Marlboro Snus, and Skoal Dry, as compared to other products analyzed here. Levels of nitrite and nitrate in new U.S. smokeless tobacco products and the Swedish snus General were lower than those in the other products. Remarkably high levels of chloride and some PAH were observed in the traditional moist snuff. Crotonaldehyde levels were about five times higher in Taboka and Marlboro Snus than in traditional products. The large variation in the levels of some toxicants and carcinogens analyzed here indicates that more effort is required from the U.S. tobacco industry to further reduce their amounts in new and traditional smokeless tobacco products.

Highly salted food and mountain herbs elevate the risk for stomach cancer death in a rural area of Japan

BACKGROUND

Although many case-control and experimental studies have shown that highly salted foods are risk factors for stomach cancer, only a few cohort studies have supported the relationship.

METHODS

In a cohort study conducted in a rural area of Japan, 8035 residents aged over 30 years (approx. 55% were female) filled out a questionnaire. Seventy-six of them died from stomach cancer during an 11-year follow-up period. In the questionnaire, intake frequencies of 29 food items, smoking and drinking habits were investigated. Tsukemono (pickled vegetables) and tsukudani (foods deep boiled in soy sauce) are highly salted foods in the area. Frequency of each food item intake was classified into three levels, and age- and sex-adjusted risks were calculated using proportional hazard models.

RESULTS

In the final model obtained by backward elimination, frequent intake of tsukemono and tsukudani and that of mountain herbs remained as significant risk factors. Compared with the least frequent intake, risk (95% confidence interval) of the most frequent intake was 5.4 (1.8-16.3) for highly salted foods (P for trend < 0.01) and 3.7 (1.4-9.6) for mountain herbs (P for trend = 0.04).

CONCLUSION

Highly salted foods and mountain herbs were important risk factors for death from stomach cancer.

High salt diets dose-dependently promote gastric chemical carcinogenesis in Helicobacter pylori-infected Mongolian gerbils associated with a shift in mucin production from glandular to surface mucous cells

Intake of salt and salty food is known as a risk factor for gastric carcinogenesis. To examine the dose-dependence and the mechanisms underlying enhancing effects, Mongolian gerbils were treated with N-methyl-N-nitrosourea (MNU), Helicobacter pylori and food containing various concentrations of salt, and were sacrificed after 50 weeks. Among gerbils treated with MNU and H. pylori, the incidences of glandular stomach cancers were 15% in the normal diet group and 33%, 36% and 63% in the 2.5%, 5% and 10% NaCl diet groups, showing dose-dependent increase (p < 0.01). Intermittent intragastric injection of saturated NaCl solution, in contrast, did not promote gastric carcinogenesis. In gerbils infected with H. pylori, a high salt diet was associated with elevation of anti-H. pylori antibody titers, serum gastrin levels and inflammatory cell infiltration in a dose-dependent fashion. Ten percent NaCl diet upregulated the amount of surface mucous cell mucin (p < 0.05), suitable for H. pylori colonization, despite no increment of MUC5AC mRNA, while H. pylori infection itself had an opposing effect, stimulating transcription of MUC6 and increasing the amount of gland mucous cell mucin (GMCM). High salt diet, in turn, decreased the amount of GMCM, which acts against H. pylori infection. In conclusion, the present study demonstrated dose-dependent enhancing effects of salt in gastric chemical carcinogenesis in H. pylori-infected Mongolian gerbils associated with alteration of the mucous microenvironment. Reduction of salt intake could thus be one of the most important chemopreventive methods for human gastric carcinogenesis.

A prospective study of dietary salt intake and gastric cancer incidence in a defined Japanese population: the Hisayama study

The results of prospective studies of the association between dietary salt intake and gastric cancer occurrence remain controversial. To examine this issue in a cohort study of a general population, 2,476 subjects aged 40 years or older were stratified into 4 groups according to the amount of daily salt intake: namely, <10.0, 10.0-12.9, 13.0-15.9, and > or = 16.0 per day and were followed up prospectively for 14 years. During the follow-up period, 93 subjects developed gastric cancer. The age- and sex-adjusted incidence was significantly higher in the second to fourth groups than in the first group (age- and sex-adjusted hazard ratio [95% confidence interval], 2.42 [1.24-4.71] for the second group; 2.10 [1.03-4.30] for the third group; 2.98 [1.53-5.82] for the fourth group). This association remained substantially unchanged even after adjusting for other confounding factors such as age, sex, Helicobacter pylori infection, atrophic gastritis, medical history of peptic ulcer, family history of cancer, body mass index, diabetes, total cholesterol, physical activity, alcohol intake, smoking habit and other dietary factors. In the stratified analysis, a significant salt-cancer association was observed only in subjects who had both Helicobacter pylori infection and atrophic gastritis (age- and sex-adjusted hazard ratio, 2.87 [1.14-7.24]). Our findings suggest that high dietary salt intake is a significant risk factor for gastric cancer; moreover, this association was found to be strong in the presence of Helicobacter pylori infection with atrophic gastritis.

Cigarette smoking and mortality due to stomach cancer: findings from the JACC Study

BACKGROUND

Several epidemiologic studies reported the positive association between cigarette smoking and stomach cancer. The prevalence of smoking in men remains high in Japan compared to other developed countries. It is therefore of great importance to determine the impact of cigarette smoking on stomach cancer among the Japanese population. The Japan Collaborative Cohort Study (JACC Study) provided an opportunity to examine the association between smoking and the risk of mortality due to stomach cancer.

METHOD

A baseline survey was conducted throughout Japan from 1988 through 1990 among 110,792 inhabitants of 45 areas. Data retrieved for 98,062 participants (43,482 male and 54,580 female) who provided sufficient information about their smoking habits, without any history of caner at the baseline. Of total 970,251 person-years, 757deaths due to stomach caner were identified.

RESULTS

Current smokers were at a higher risk of death due to stomach cancer than non-smokers (Hazard ratio=1.36; 95% confidence interval [CI]: 1.07, 1.73). The risk of stomach cancer for men who smoked 15 or more cigarettes per day was approximately 1.4-fold greater than that of non-smokers, and those who smoked 35 or more cigarettes per day had an approximately 1.7-fold higher risk of stomach cancer, although the dose-response trend among men was unclear (p for trend=0.063). No associations between smoking and stomach cancer were detected among women.

CONCLUSION

The present results, together with previous findings, strongly support a hypothesis that cigarette smoking increases the risk of stomach cancer in Japanese men.

Salt, salted food intake, and risk of gastric cancer: epidemiologic evidence

Because gastric cancer is still the most common cancer, its prevention is one of the most important aspects of Japan's cancer control strategy. Observations among Japanese immigrants in the USA and Brazil based on the geographic differences, the trend in cancer incidence with time, and the change in incidence patterns indicate that gastric cancer is closely associated with dietary factors, such as the intake of salt and salted food. In international and intra-Japanese ecological studies, the average salt excretion level, estimated using randomly selected 24-h urine samples in each population, was closely correlated with gastric cancer mortality. Several case-control and cohort studies, including the author's recent works, have shown that a higher intake of some traditional salt-preserved food and salt per se, which was estimated using a validated food-frequency questionnaire, was associated with a risk of gastric cancer. While salted food intake may increase the risk of Helicobacter pylori infection, it can also act synergistically to promote the development of gastric cancer. Based on substantial evidence about the association between salt and salted food intake and the risk of gastric cancer from ecological, case-control, and cohort studies conducted in Japan and other countries, as well as mechanistic plausibility, dietary modification involving less salt and salted food intake is a practical strategy with which to prevent gastric cancer.

Prospective study of three major dietary patterns and risk of gastric cancer in Japan

Dietary pattern analysis is an alternative and complementary approach to identify the relationship between diet and the risk of chronic disease. This study was aimed at investigating the associations between dietary patterns and the risk of gastric cancer in Japan. Using baseline data from a prospective study of 20,300 men and 21,812 women, we conducted factor analysis and identified 3 major dietary patterns, healthy, traditional and Western, and calculated the factor scores of each pattern for individuals. During 10 years of follow-up, 400 cases of gastric cancer were identified. We found an inverse association between the healthy pattern and gastric cancer risk in women [rate ratio for highest quartile (RR) = 0.56; 95% CI = 0.32-0.96; p for trend = 0.03], but not in men. In contrast, the traditional pattern was significantly associated with the increased risk of gastric cancer in both genders (for men, RR = 2.88, 95% CI = 1.76-4.72; for women, RR = 2.40, 95% CI = 1.32-4.35). The Western pattern was not associated with risk. These associations persisted in histologic subtypes. Our findings support the idea that the healthy pattern decreased the risk of gastric cancer among females, while the traditional pattern increased the risk in both genders.

Salt and salted food intake and subsequent risk of gastric cancer among middle-aged Japanese men and women

Evidence on the association between salt intake and gastric cancer is sparse, especially in prospective studies. We conducted a population-based prospective study in Japan, where the majority of men has been infected with Helicobacter pylori. A total of 18 684 men and 20 381 women aged 40–59 years who reported their dietary habits and did not report any serious disease at baseline were followed from 1990 to 2001. A total of 486 cases, 358 men and 128 women, with histologically confirmed gastric cancer were documented among them. The quintile category of salt intake was dose-dependently associated with gastric cancer risk in men after adjusting for potential confounding factors (P for trend <0.001), while a trend was not clear in women (P for trend=0.48). Although stratification by study area, with varied salt intake and gastric cancer incidence, attenuated the observed clear associations with salt and salted foods, the frequency categories of highly salted foods such as salted fish roe and salted fish preserves were strongly associated with the risk in both sexes. Restriction of salt and salted food intake is a practical strategy to prevent gastric cancer in areas with high risk.

The epidemiology of gastric cancer

Gastric cancer mortality has declined markedly around the world. In South Australia, the reduction approximated 40% over the last 20 years. Possible reasons include: better refrigeration; reduced consumption of salted, smoked, and chemically preserved foods; increased intake of fruit and vegetables; and improved living standards and a greater use of antibiotics, which may have reduced Helicobacter pylori infection. Reductions generally have been greater for intestinal than diffuse histopathologies. Gastric cancer remains the second leading cause of cancer death worldwide, probably accounting for about 10% of newly diagnosed cancers. High rates apply to Japan, China. Central and South America, Eastern Europe, and parts of the Middle East, and low rates to North America, Australia and New Zealand, Northern Europe, and India. Rates usually are higher in lower socioeconomic groups. Five-year relative survivals of around 20% or less are frequently reported. A figure of 50% or more has been cited for Japan, where there has been radiological screening, although this exceptional figure could have been affected artificially by lead-time and related effects. Male-to-female incidence ratios generally are in the 1.5-2.5 range, with higher ratios for intestinal than diffuse cancers and higher-risk populations. In South Australia, the ratio has been 1.8 to one, although higher at 4.6 to one for cardia lesions. Recent increases in cardia cancers, especially in males in populations of European extraction, often are accompanied by increases for esophageal adenocarcinoma. It is estimated that the global burden of gastric cancer could be reduced by up to 50% by dietary changes that included an increased intake of fruit and vegetables.

Seasonal misclassification error and magnitude of true between-person variation in dietary nutrient intake: a random coefficients analysis and implications for the Japan Public Health Center (JPHC) Cohort Study

OBJECTIVE

We examine (1) the extent to which seasonal diet assessments correctly classify individuals with respect to their usual nutrient intake, and (2) whether the magnitude of true variation in intake between individuals is seasonal. These effects could lead, respectively, to bias in estimates of relative risk for associations between usual nutrient exposure and disease, and to an increase in required sample size.

SUBJECTS AND SETTING

One hundred and twenty-seven families in four regions of the Japan Public Health Center (JPHC) Cohort Study.

DESIGN

On average, 48 weighed daily food records were collected per family over six seasons of 1994 and 1995.

RESULTS

A random slopes regression model was used to predict the correlation between seasonal and annual average intakes, and to estimate true between-person variation in intakes by season. Mean vitamin C intake was greatest in summer and autumn, and seasonal variation was attributable to the consumption of fruit and vegetables. Predicted correlations between seasonal and annual average vitamin C intake ranged from 0.62 to 0.87, with greatest correlations in summer and autumn. True between-person variation in vitamin C intake was also strongly seasonal, ranging from 45 to 78% of total variance, and was again greatest in summer and autumn. These effects were less seasonal among energy and 13 other nutrients.

CONCLUSIONS

It may be possible substantially to reduce both seasonal misclassification of individuals with respect to their usual vitamin C intake, and required sample size, by asking subjects to report high-season intake of fruit and vegetables in the JPHC Study.

Work, salt intake and the development of stomach cancer

An excess of stomach cancer among workers has been observed and it could be argued that men whose occupation involves heavy work eat more and are consequently exposed to a greater quantity of carcinogens in their food. Working under conditions of heat stress greatly increases a worker's salt excretion by as much as 0.1-15.0 g through sweating during one shift of work. Workers exposed to heat stress had consumed daily as much as from 13.0 to 38.0 g of salt, which is much higher than the safe level of 6 g/person/day recommended by the WHO, to keep a balance of salt in the body. Because salt strongly enhances and promotes chemical gastric carcinogenesis and Helicobacter pylori infection in both humans and animals, there is an association between work, salt intake, and the development of stomach cancer among workers in particular and in humans in general.

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.

Relationship between mineral and trace element concentrations in drinking water and gastric cancer mortality in Japan

It is well known that the incidence and mortality from gastric cancer in Japan are the highest in the world. This is thought to be due, in part, to dietary habit, including a high salt intake. There are, however, no epidemiological reports to describe the relationship between ingestion of mineral and trace elements and gastric carcinogenesis. In this study, we determined the concentrations of 14 elements in drinking water from 34 water treatment plants in Aomori Prefecture, Japan, and studied how element concentrations were geographically associated with gastric cancer mortality rate. Gastric cancer mortality was calculated from the data of the Annual Aomori Health Report. Multiple regression analysis (stepwise method of decreasing the number of variables) was performed by using age-adjusted mortality of gastric cancer by gender as objective variables and each element concentration as an explanatory variable. The standardized partial regression coefficient was significant in men for zinc (-0.59, P = 0.004), lead (1.01, P = 0.013), strontium (1.23, P = 0.007), and selenium (-1.62, P = 0.004), whereas it was significant in women for lead (-0.65, P = 0.022), strontium (0.51, P = 0.035), and gold (0.70, P = 0.019). It is suggested that selenium and zinc may aid in the prevention of gastric carcinogenesis. However, the significant relationship of sodium (a component of salt) to gastric carcinogenesis was not observed, although many previous epidemiological studies in Japan have shown this relationship.

Prospective study of educational background and stomach cancer in Japan

BACKGROUND

Different lifestyle choices are commonly regarded as a reflection of socioeconomic status, and the latter is inversely correlated with the risk of developing stomach cancer. However, the details of this association are still unclear in terms of the degree to which lifestyle factors are having impact. To explain the correlation between socioeconomic status and stomach cancer, we therefore examined the roles played by different lifestyle factors.

METHODS

A prospective cohort study of diet and cancer was initiated in Japan during 1988. Data were collected by means of a self-administered questionnaire. A follow-up survey was conducted annually, and the cause of death was recorded from the death certificate. The total of 127,477 study participants resided in 45 areas of Japan, and we retrieved data for 18,746 men and 26,184 women for the present analysis. After 328,030 person-years of follow-up, 379 deaths from stomach cancer were detected: 261 in men and 118 in women.

RESULTS

For men, the age-adjusted relative risk was lowest in the highly educated group (relative risk = 0.72, 95% CI: 0.50-1.04). Relative risk after adjustment for age and dietary choices (including pickles, vegetables, fruit, green tea, and preference for salty foods) was the same as the age-adjusted relative risk (relative risk = 0.72, 95% CI: 0.50-1.04).

CONCLUSION

The expected inverse correlation between education level and death from stomach cancer was observed in men. However, this association could not be explained by differences in dietary habits, smoking, or alcohol consumption associated with socioeconomic status.

Effect of smoking on serum pepsinogen I level depends on serological status of Helicobacter pylori

Serum pepsinogen (sPG) levels are used in gastric cancer screening programs. However, modification of sPG levels by smoking habit, according to the status of Helicobacter pylori (H. pylori) infection has been little investigated. This study investigated the effects of smoking on serum levels of pepsinogen I (PG I), pepsinogen II (PG II), and gastrin by IgG titer of antibody against H. pylori (Hp-IgG titer) using the data from 356 current-smokers and 262 non-smokers (133 never-smokers and 129 ex-smokers) in a cross-sectional study of 618 men aged 40 to 49 years. PG I, PG II, PG I / PG II ratio and gastrin were significantly associated with Hp-IgG titer in never-smokers [Spearman's correlation coefficient (95% confidence interval): 0.23 (0.07, 0.39), 0.52 (0.41, 0.63), -0.40 (-0.54,-0.27), and 0.25 (0.10, 0.41), respectively]. However, the correlation coefficients of PG I and PG II decreased in current-smokers, 0.02 (-0.1, 0.13) and 0.32 (0.22, 0.42), respectively. In H. pylori seronegative and low titer cases, the mean PG I level was significantly (P < 0.01) higher in current-smokers, compared with non-smokers. However, in high titer cases, the mean PG I level was lower in current-smokers. Mean PG II and gastrin levels, and PG I / PG II ratio did not differ according to smoking habits by Hp-IgG titer. The gastrin level was significantly correlated with PG II, but not PG I. These data indicate that current smoking influences the serum PG I level depending on Hp-IgG titer and the associations between sPGs and Hp-IgG titer. Gastrin is not involved in the modification of PG I levels by smoking.

In vivo DNA damage in gastric epithelial cells

A number of risk factors have been linked epidemiologically with gastric cancer, but studies of DNA damage in gastric epithelial cells are limited. The comet assay is a simple technique for determining levels of DNA damage in individual cells. In this study, we have validated the comet assay for use in epithelial cells derived directly from human gastric biopsies, determined optimal conditions for biopsy digestion and investigated the effects of oxidative stress and digestion time on DNA damage. Biopsies taken at endoscopy were digested using combinations of pronase and collagenase, ethylenediaminetetra-acetic acid (EDTA) and vigorous shaking. The resultant cell suspension was assessed for cell concentration and epithelial cell and leukocyte content. A score for DNA damage, the comet %, was derived from the cell suspension, and the effect of various digestion conditions was studied. Cells were incubated with H(2)O(2) and DNA damage was assessed. Pronase and collagenase provided optimum digestion conditions, releasing 1. 12x10(5) cells per biopsy, predominantly epithelial. Of the 23 suspensions examined, all but three had leukocyte concentrations of less than 20%. The comet assay had high inter-observer (6.1%) and inter-assay (4.5%) reproducibility. Overnight storage of the biopsy at 4 degrees C had no significant effect on DNA migration. Comet % increased from a median of 46% in untreated cells to 88% in cells incubated for 45 min in H(2)O(2) (p=0.005). Serial 25-min digestions were performed on biopsies from 13 patients to release cells from successively deeper levels in the crypt. Levels of DNA migration were significantly lower with each digestion (r=-0.94, p<0.001), suggesting that DNA damage is lower in younger cells released from low in the gastric crypt. The comet assay is a reproducible measure of DNA damage in gastric epithelial cells. Damage accumulates in older, more superficial cells, and can be induced by oxidative stress.

Nutrition and dietary carcinogens

Three major factors for human carcinogenesis are (i) cigarette smoking, (ii) infection and inflammation and (iii) nutrition and dietary factors. Nutrition and dietary factors include two categories, namely genotoxic agents and constituents including tumor promotion-associated phenomena. This article first describes the genotoxic agents as microcomponents. These are mutagens/carcinogens in cooked food, fungal products, plant and mushroom substance, and nitrite-related materials, polycyclic aromatic hydrocarbons and oxidative agents. Emphasis has been given to heterocyclic amines (HCAs) to which humans are continuously exposed in an ordinary lifestyle. HCAs in food are mainly produced from creatin(in)e, sugar and from amino acids in meat (upon heating). They are imidazoquinoline and imidazoquinoxaline derivatives and phenylimidazopyridine. HCAs are pluripotent in producing cancers in various organs including breast, colon and prostate. Discussion is also given to plant flavonoids which are mutagenic but not carcinogenic. As a macrocomponent, overintake of total calories, fat and sodium chloride is discussed from the viewpoint of the increase of genetic alterations in tissues and of tumor promotion-associated issues. Studies of nutrition and dietary condition will eventually lead us to cancer prevention, namely delay of onset of cancer to the late phase of human life, which is called 'natural-end cancer' (Tenju-gann).

Plasma antioxidant vitamins and carotenoids in five Japanese populations with varied mortality from gastric cancer

To examine the geographic associations between plasma antioxidant levels and gastric cancer risk, we conducted an ecological study in five regions of Japan representing the threefold variation in the disease mortality within the country. Subjects were 634 men aged 40-49 years sampled randomly from the five regions with 72% response rates. Plasma concentrations of five carotenoids (beta-carotene, alpha-carotene, lycopene, lutein, and zeaxanthin), alpha-tocopherol, and ascorbic acid were measured, and the mean levels were correlated with age-adjusted mortality rates from gastric cancer. beta-Carotene and alpha-tocopherol were inversely correlated with gastric cancer rates (r = -0.31 and -0.89, respectively). alpha-Carotene and lycopene showed stronger inverse correlation than did beta-carotene (r = -0.67 and -0.56, respectively), but these relations disappeared after the exclusion of one outlying region in Okinawa with the lowest mortality. In contrast, ascorbic acid revealed a negative correlation with the exclusion of this outlier (r = -0.61). Lutein and zeaxanthin were not inversely associated with risk. The results suggest that plasma levels of beta-carotene and alpha-tocopherol, and possibly alpha-carotene, lycopene, and ascorbic acid, may partly account for the regional difference in gastric cancer mortality in Japan.

Validity of a self-administered diet history questionnaire for assessment of sodium and potassium: comparison with single 24-hour urinary excretion

We developed a self-administered diet history questionnaire (DHQ) for use in prevention and control of cardiovascular diseases and cancer, and validated it by comparison with single 24-h urinary excretion of sodium (Na) and potassium (K). The subjects were 154 male and 69 female freshmen university students. Mean intakes (mmol/day) assessed by DHQ and the urinary excretion of Na were 196 and 165 respectively for men and 179 and 136 respectively for women. Those of K were 61.5 and 43.9 respectively for men and 56.8 and 41.6 respectively for women. The ratios of urinary excretion to dietary intake of Na were 0.97 in men and 0.84 in women. Those of K were 0.78 in men and 0.80 in women. The results for both Na and K were reasonable, except for Na in men. When Pearson correlation was examined between dietary and urinary Na and K, no significant correlations for Na in men (r=0.14) or women (r=0.23, p=0.06), or significant correlations for K in men (r=0.34, p<0.001) or women (r=0.40, p<0.001) were observed. The results suggest a reasonable ability to estimate a subject mean for Na in women, K in both sexes, and individual level for K for both sexes. The validity for individual level for Na intake is not conclusive because the duration of urine collection was too short.

Diet, nutrients, and gastrointestinal cancer

Tobacco and alcohol use are strong risk factors for cancer of the upper gastrointestinal tract. Saturated fat and red meat intake also appear to increase the risk of colorectal cancer. The strongest and most consistent dietary protective factors for gastrointestinal cancer are vegetables and fruits. Some micronutrients show beneficial effects, but the degree of protection is less than that observed from whole plant foods. Substantial decreases in the morbidity and mortality from gastrointestinal cancer could occur with more widespread adoption of dietary guidelines designed for cancer prevention.

Within- and between-person variations in portion sizes of foods consumed by the Japanese population

There has been considerable controversy about the utility of asking separate questions on portion sizes in addition to items on consumption frequencies in food frequency questionnaires. One argument against this type of inquiry is that, for most foods, within-person variation of portion size is greater than between-person variation, making it difficult to characterize "usual" or long-term average serving sizes. The authors studied the relative effects of within- and between-person variances in portion sizes of 69 food items using three-day food record data collected from 335 Japanese men and women. Total variance in the portion size for each food was partitioned into within- and between-person components by analysis of variance. Although the ratios of within- to between-person variances in log(e)-transformed portion sizes were > 1.0 for the majority of foods (50 of 69 items, median = 1.7), they were smaller than or close to unity for subgroups of foods that were the major sources of nutrient variables of relevance to diet-cancer associations, such as total energy (rice, calcium (milk), sodium (pickled vegetables), and alcohol (beer, shochu, whiskey). These results indicate that the relative contributions of within- and between-person variations in portion size may vary among foods, and therefore investigators should consider the balance between the advantages and disadvantages of obtaining portion size data separately from intake frequencies when designing food frequency questionnaires.

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.

Food consumption and gastric cancer mortality in five regions of Japan

To explore the causes of the threefold variation in mortality rate from gastric cancer in Japan, we studied the geographic correlations between food consumption and age-adjusted mortality rates in five regions, which covered the areas with the highest and lowest mortality rates in the country. Six hundred thirty-four men and wives of 373 of the men sampled from the general populations in these districts were interviewed about intake frequency of 38 food items. Age-adjusted mean frequencies of food intake differed markedly among the regions, in which 32 food items for men and 28 for women showed a significant difference (p < 0.05). Rank correlation coefficients between the average frequencies and the mortality rates with adjustment for sex and prevalence of current smokers were 0.49, 0.32, 0.36, -0.88, and -0.57 for rice, bean paste soup, pickled vegetables, green vegetables, and yellow vegetables, respectively. These results suggest that the regional differences in consumption of these foods may account partly for the geographic variation in gastric cancer mortality in Japan.

Nutrient consumption and gastric cancer mortality in five regions of Japan

To explore the causes of the threefold variation in mortality rate from gastric cancer in Japan, we studied the geographic correlations between nutrient consumption and the disease in five Public Health Center districts including the regions with the highest and lowest mortality rates in the country. In the winters of 1989-1991, a three-day weighed food record was collected from 207 men and the wives of 165 of the men sampled from the five districts. The average daily consumption of selected nutrients was computed and correlated with the age-adjusted mortality rates from gastric cancer. Partial rank correlation coefficients adjusted for sex and other nutrients were 0.45, -0.80, -0.20, and -0.07 for sodium, carotene, ascorbic acid, and retinol, respectively. The results suggest that variation in gastric cancer mortality in Japan may be partly accounted for by the regional differences in consumption of sodium, carotene, and possibly ascorbic acid.

Nutrition and stomach cancer

Epidemiologic evidence on the relation between nutrition and stomach cancer is reviewed. Stomach cancer shows a distinct international variation and dramatic worldwide decline. These descriptive features suggest that dietary factors are important in determining the risk of stomach cancer. The authors assessed relevant data regarding specific dietary hypotheses in the etiology of stomach cancer. A negative association with fresh vegetables and fruits is highly consistent in numerous case-control studies in different populations. Both epidemiologic and experimental data suggest that vitamins C and carotenoids lower risk of stomach cancer. Evidence is sparse and inconsistent as to protective effects of vitamin E and selenium. Epidemiologic studies have not lent, and will not provide, supportive evidence for an etiologic role of nitrate intake. High salt intake has been associated with an increased risk in many case-control studies and limited cohort studies. Taken together with animal data, it is considered that high salt intake is a risk factor for stomach cancer. Both epidemiologic and experimental data are inconclusive as to whether high-starch diets confer an increased risk. Cohort studies using quantitative dietary assessment and biologic measurement of micronutrients are needed for further understanding of etiologic roles of dietary factors in the causation of stomach cancer.

Salty food intake and risk of Helicobacter pylori infection

To clarify the risk factors for Helicobacter pylori infection, which is considered to play an etiologic role in atrophic gastritis, duodenal ulcer and gastric cancer, various parameters including diet and socioeconomic characteristics were compared between H. pylori-infected and non-infected men. In a cross-sectional study of 634 men aged 40 to 49 years selected randomly from five areas with different rates of gastric cancer mortality, 474 of 628 men evaluated were positive for IgG antibody against H. pylori. After logistic regression analysis adjusted for area, the results showed a significant association between frequent intake of pickled vegetables and prevalence of H. pylori antibody (odds ratios against men who consume < 1 day/week 1.19 for 1-2 days/week, 1.92 for 3-4 days/week, 1.90 for 5-7 days/week; P for trend = 0.02). Daily consumption of miso soup was also associated with an increased risk (odds ratio against non-daily consumer = 1.60, 95% confidence interval = 1.03-2.49). Occupation, number of siblings, education, smoking and alcohol drinking, and other dietary habits were not significantly associated with the prevalence of infection in this population. Although there are limitations in a cross-sectional study such as this, consumption of salty foods appears to increase the risk of H. pylori infection, which could be a marker of salty food intake or an intermediate risk factor in the etiologic sequence between salty food intake and gastric cancer.

Helicobacter pylori, dietary factors, and atrophic gastritis in five Japanese populations with different gastric cancer mortality

In a cross-sectional study of 634 men aged 40 to 49 years, randomly selected from five areas of Japan with different rates of gastric cancer mortality, 121 men of 624 evaluated were diagnosed as having atrophic gastritis through serum pepsinogen I < 70 ng/ml and the pepsinogen I (PGI)/pepsinogen II (PGII) ratio < 3.0. We examined the relation of Helicobacter pylori (H. pylori) antibodies and dietary factors, including plasma level of antioxidant micronutrients, to the presence of atrophic gastritis. Presence of H. pylori IgG antibodies was associated with increased risk of atrophic gastritis (odds ratio [OR] = 1.9, 95 percent confidence interval [CI] = 1.1-3.3). As the level of plasma beta-carotene increased, we found a steady decrease in the risk of atrophic gastritis (OR for second quartile = 0.7, third quartile = 0.6, fourth quartile = 0.4, with CI = 0.2-0.8). Frequent intake of yellow vegetables also was associated with lower risk, while frequent intake of soybean products was related to increased risk. Although H. pylori antibodies, beta-carotene level, and intake of soybean products were all significant in the multivariate analysis, these factors did not explain the differences in atrophic gastritis prevalence among the five regions. The analysis of these risk factors in relation to each pepsinogen marker showed that although both H. pylori infection and low plasma beta-carotene were associated with the decreased level of serum PGI/II ratio, the former was derived from the increase of PGII, which is common in early stage of atrophic gastritis, and the latter from the decrease of PGI, which is specific to severe atrophic gastritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Large-scale, population-based prospective studies in Japan

Large scale, population-based prospective studies have increasing importance for the study of common cancers in view of the possibility of advancing the understanding of different risk factors in the initiation, promotion and progression phases during what is thought to be the long process of human carcinogenesis. The permanent registration system in Japan ("Koseki") simplifies the follow-up of registered participants of such cohorts. The population-based cohort studied by Hirayama and the cohort of the atomic bomb survivors started during the 1960s are examples of such possibilities in Japan. Rapidly changing patterns of disease and lifestyles during the last 30 years require new population-based prospective studies focusing on a different set of exposures and with increased detail of exposure assessment. We have established a new population-based prospective study, the "Koseisho" cohort, between 1990 to 1992, following a cross-sectional study, using various biomarkers in five health centre districts. The Koseisho cohort comprises approximately 170,000 people aged 40-59 or 40-69 in 12 different health centre districts. The data are linked with the mass screening program registry data every year, and the sera and buffy coats collected at the beginning of the study will be stored at -80 degrees C for at least 10 years. We intend to integrate various sources of information about health conditions for the prevention of chronic diseases in these cohort areas. Nutritional practices are one of our main interests, and repeated surveys by different methods are planned. Although all death certificates are collected through the health centres, disease registration committees were established in each district to register incident cases of both cancer and certain cardiovascular diseases. Representative population-based prospective studies in Japan are briefly reviewed and introduced.

A case-control study of single and multiple stomach cancers in Saitama Prefecture, Japan

A case-control study of stomach cancer was done in Saitama Prefecture, Japan, in relation to dietary, smoking, and drinking habits. The study was based on two sets of cases (216 male single and 35 male multiple stomach cancer cases newly diagnosed and of adenocarcinoma type), and 483 male controls derived from residents of Saitama Prefecture. Dietary habits were investigated for the intake of 12 separate foods and 12 food groups by means of a food frequency questionnaire, including individual taste preferences. Among the single stomach cancer series, dose-response relationships were observed for 7 dietary items (preference for salty foods, miso soup, boiled fish, pickled vegetables, nuts, raw vegetables, and seaweed) in the multiple logistic regression analysis. As for the multiple stomach cancer case series, dose-response relationships were observed for 3 dietary items (miso soup, fruits, and seaweed) in the multiple logistic regression analysis. Cigarette smoking and alcohol use were not significantly related to the risk of either single or multiple stomach cancer.

A case-control study of stomach cancer and its relation to diet, cigarettes, and alcohol consumption in Saitama Prefecture, Japan

A case-control study of stomach cancer in relation to dietary, smoking, and drinking habits was undertaken in Saitama Prefecture, Japan. The study was based on 294 cases of newly diagnosed adenocarcinoma of the stomach at a single institution, 294 general population controls (matched by sex, age, and administrative division), and 202 hospital controls. Dietary habits were investigated based on the intake of 12 separate foods and 12 food groups in a food frequency questionnaire, together with individual food preferences. The consumption of raw vegetables was inversely related to the risk of stomach cancer, with a dose-response relation observed consistently in the comparisons with both sets of controls. Current cigarette smokers (1-29/day) had an increased risk (relative risk = 1.8, 95 percent confidence interval = 1.1-3.0) compared with nonsmokers in the general population controls, but no dose-response effect with heavier cigarette smoking. Alcohol use did not affect the risk of stomach cancer. In the multiple logistic regression, the consumption of raw vegetables showed a protective effect on stomach cancer while cigarette smoking had no significant association, in both sets of controls.

Toward the primary prevention of cancer

This is the threshold of an era when many of the most prevalent human cancers can, to a significant extent, be prevented through life-style changes or medical interventions. For lung cancer, the leading cause of cancer deaths in the United States, the major cause, cigarette smoking, is known and strategies for reducing smoking are slowly succeeding. Dietary changes can reduce the risk of developing large bowel cancer, the second most common cancer overall. The etiology of the major cancer in women, cancer of the breast, is sufficiently well understood that large-scale medical intervention trials are imminent. Recent changes in the incidence and mortality of these and the other major human cancers are reviewed with a brief explanation as to why these changes have occurred, followed by a summary of the state of knowledge regarding the major causes of cancer.