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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An experimental study on rats was performed to observe pathogenetic factors causing cancerogenesis in operated stomach. In sets I and II without exogenous carcinogen exposition 450 rats were operated upon by a different methods. In groups I it was B II gastrectomy, B II with Braun's anastomosis, B II in Roux en Y modification, B I and B I with jejunal interposition. In group II non-resective methods were tested: gastroenterostomy, gastroenterostomy with Braun's anastomosis, gastroenterostomy in Roux en Y modification, and vagotomy with pyloroplasty. In the group III 147 rats with different gastric operations were submitted to oral nitrate and nitrate with ascorbic acid exposition. The results confirmed significant pathogenetic influence of enterogastric reflux on cancerogenesis in the operated stomach. Ascorbic acid added to the exogenous cancerogen leads to a suppression of development of gastric cancer in rats.
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PMID:Pathogenesis of carcinoma in operated stomach--an animal model. 141 Dec 42

Sex-specific mortality rates for selected cancer sites (including oesophagus, stomach, liver, lung, colorectum, breast and cervix) and a variety of biochemical indicators of antioxidant status, enzyme activity and oxidative stress (including plasma levels of beta-carotene, alpha-tocopherol, ascorbic acid, selenium, glutathione peroxidase, catalase, superoxide dismutase, iron, copper, zinc, total cholesterol and lipid peroxide) were examined in an ecological study of 65 mostly rural counties in the People's Republic of China. The wide range of both mortality rates and biochemical values and the measurement of a comprehensive set of biochemical indicators permitted both simple correlational and multivariate analyses of the joint and relative effects of each factor on site-specific cancer mortality. Plasma levels of dietary antioxidants were consistently negatively correlated with cancer mortality rates. Ascorbic acid was most strongly negatively associated with most cancers and selenium with oesophageal and stomach cancers. beta-carotene was found to have a protective effect independent of retinol, particularly for stomach cancer.
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PMID:Antioxidant status and cancer mortality in China. 152 64

Ascorbic acid has been shown to decrease nitrosation in vivo, and epidemiological data suggest that the consumption of foods rich in this vitamin is associated with a reduced risk for gastric cancer. In order to study this suggestion further, fasting gastric juice samples were obtained from 62 high-risk patients (seven with atrophic gastritis, ten with pernicious anaemia, ten with partial gastrectomy, 21 with vagotomy and drainage and 14 with highly selective vagotomy), before, during four weeks' treatment with 1 g ascorbic acid four times daily, and four weeks after treatment. Samples were analysed for pH, total and nitrate-reducing bacterial counts, nitrite and N-nitroso compounds. Treatment with ascorbic acid lowered the median pH only in the vagotomized patients (p less than 0.001) but resulted in a reduction in median nitrate-reducing bacterial counts and in nitrite and N-nitroso compound concentrations in all groups, except for an increase in the nitrate-reducing bacterial count in atrophic gastritis patients and in nitrite in those with pernicious anaemia. These data suggest that treatment with a high dose of ascorbic acid reduces the intragastric formation of nitrite and N-nitroso compounds.
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PMID:Effect of ascorbic acid on the intragastric environment in patients at increased risk of developing gastric cancer. 185 37

Antioxidant micronutrients are one of the body's primary defenses against free radicals and reactive oxygen molecules. Carotenoids, vitamin C, and vitamin E trap these molecules, and selenium is an essential component of an antioxidant enzyme. There is considerable support from animal studies for a protective effect of antioxidant micronutrients on cancer. However, the role of these micronutrients in cancer prevention in humans is less clear. Diet studies suggest protective effects of fruits and vegetables on risk of cancer at several sites. Inverse associations between dietary carotenoids and serum beta-carotene and lung cancer have been observed repeatedly. Vitamin C has also been consistently inversely associated with risk of oral and esophageal cancer in diet studies and with stomach cancer in both diet and plasma studies. It remains unknown, however, whether carotenoids and vitamin C or some other component of fruits and vegetables, the primary sources of these micronutrients, prevent cancer in humans. Selenium has been inversely correlated with cancers at numerous sites in ecologic studies, but observational studies do not provide strong support for a protective effect of selenium on cancer at any site. There also is not strong support for a protective effect of vitamin E on cancer in humans. Results of studies on the association of antioxidant micronutrients with cancer at many sites are inconsistent. This could be due to lack of a true protective effect or could be related to methodologic problems in assessing dietary intake in epidemiologic studies.
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PMID:Antioxidant micronutrients in cancer prevention. 202 68

A cohort of Hawaii Japanese men was assembled for epidemiologic studies of heart disease and cancer. Diet and tobacco consumption data were obtained from 1965 to 1968 and from 1971 to 1975. Biopsies from sites at maximal, intermediate, and minimal risk of intestinal metaplasia were performed on 350 men. Metaplasia was found in 234 men. Gastric cancer was found in 9/234 with metaplasia (3.8%) and 1/116 men without metaplasia (0.89%). Nitrite-rich salty foods (e.g., cured meats) were directly related to metaplasia at both examinations. Vitamin C intake did not appear to have prevented the development of intestinal metaplasia. Smoking was directly related to the presence of metaplasia, but the association was weaker than was observed for cured meats. The strong association between nitrite-rich salty foods and metaplasia appears to be uniform from one study to another, as is the lack of a consistent relation between metaplasia and either smoking or vitamin C consumption. Heavy smokers were more likely to have metaplasia than were nonsmokers, but these associations were weaker than were those with cured meats.
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PMID:Impact of diet and smoking on risk of developing intestinal metaplasia of the stomach. 231 88

A case-control study involving interviews with 1,016 gastric cancer (GC) patients and 1,159 population-based controls in high- and low-risk areas was conducted to evaluate dietary factors and their contribution to the marked geographic variation in mortality from this cancer within Italy. Risks of GC were found to vary significantly with estimated nutrient intake. Risk rose with increasing consumption of nitrites and protein, and decreased in proportion to intake of ascorbic acid, beta-carotene, alpha-tocopherol, and vegetable fat. The associations with nitrite and beta-carotene tended to fade, however, in multivariate analyses adjusting for intake of other nutrients. Ascorbic acid showed the strongest geographic gradient, with highest consumption in low-risk areas. The findings suggest that the protective effects we previously reported for consumption of fresh fruit, fresh vegetables and olive oil may be linked to the vitamins C and E contained in these foods. The findings are consistent with the hypothesis that N-nitroso compounds are involved in GC risks, since elevated risks were apparent for agents (nitrites, protein) that promote nitrosation, while decreased risks were found for nutrients (ascorbic acid and alpha-tocopherol) which inhibit the process.
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PMID:A case-control study of gastric cancer and diet in Italy: II. Association with nutrients. 233 93

It has been suggested that endogenously formed N-nitroso compounds are involved in the aetiology of gastric cancer. In the model of gastric carcinogenesis postulated by Correa, gastric atrophy is an important early stage in the progression to carcinoma which results in the loss of stomach acidity, and colonization of the stomach by bacteria. As a consequence of the metabolic activity of these bacteria intragastric nitrite (a precursor to N-nitroso compounds) and possibly carcinogenic N-nitroso compounds become elevated, which may hasten the progression to carcinoma. Vitamin C has been shown to be an effective inhibitor of acid-catalysed N-nitroso compound formation, in vivo and in vitro, and this has been attributed to its relatively rapid reaction with nitrite in contrast to the slower rates of reaction of nitrite with secondary amines. However, N-nitroso compound formation in the achlorhydric stomach must proceed by mechanisms which operate at neutral pH values. One potential mechanism involves the enzymatic catalysis of N-nitrosation by a subpopulation of the bacteria colonizing the achlorhydric stomach which catalyse these reactions and in particular denitrifying organisms. In this study, we examined the effect of vitamin C on the formation of N-nitrosomorpholine from morpholine and nitrite when mediated by cells of an actively N-nitrosating denitrifying bacterium (Pseudomonas aeruginosa, BM1030) at neutral pH. Despite the fact that vitamin C ordinarily shows little reactivity towards nitrite at neutral pH it did prove to be a potent inhibitor of bacterial N-nitrosamine formation. This study provides some justification for the use of vitamin C as an inhibitor of endogenous N-nitrosation regardless of gastric pH.
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PMID:The inhibition of bacterially mediated N-nitrosation by vitamin C: relevance to the inhibition of endogenous N-nitrosation in the achlorhydric stomach. 249 12

Fasting gastric juice pH and concentrations of vitamin C in gastric aspirate and plasma were measured in 73 patients undergoing endoscopy. Vitamin C concentrations were significantly lower in those with hypochlorhydria (pH greater than 4; n = 23) compared with those with pH less than or equal to 4 (p less than 0.005) and there was a significant correlation between gastric juice and plasma concentrations (p = 0.002). Patients with normal endoscopic findings had significantly higher intragastric concentrations of vitamin C than those with gastric cancer (p less than 0.001), pernicious anaemia (p less than 0.005), gastric ulcer (p less than 0.01), duodenal ulcer (p less than 0.05), or after gastric surgery (p less than 0.01). There was a strong trend (0.05 less than p less than 0.1) towards lower intragastric concentrations of vitamin C in patients with chronic atrophic gastritis. In vitro, vitamin C concentrations remained stable in acidic but fell significantly over 24 hours in alkaline gastric aspirate. Gastric secretory studies in five volunteers showed that vitamin C concentrations increased significantly after intramuscular pentagastrin. These findings suggest that the low fasting levels of vitamin C in hypochlorhydric gastric juice may be caused by chemical instability and that vitamin C may be secreted by the human stomach.
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PMID:Vitamin C in the human stomach: relation to gastric pH, gastroduodenal disease, and possible sources. 271 77

Ascorbic acid, the reduced form of vitamin C, may protect against gastric cancer. Accordingly, this study assessed the variability of ascorbic acid and vitamin C in the gastric juice of 77 patients with dyspepsia. There was a vitamin C concentration gradient from gastric juice down to plasma in subjects with normal gastric mucosa, but not in those with chronic gastritis. Patients with chronic gastritis had significantly lower gastric concentrations of vitamin C and ascorbic acid, and ascorbic acid concentrations were especially low in subjects with hypochlorhydria. The presence of the concentration gradient suggests that a mechanism for the secretion of vitamin C into the stomach exists. This is compromised by chronic gastritis. The very low ascorbic acid concentrations in hypochlorhydria may be a consequence of oxidation by bacterial nitrite. Those patients who by the Correa model are at greatest risk for gastric cancer have the lowest gastric levels of ascorbic acid.
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PMID:Ascorbic acid in the human stomach. 274 55

Although no absolute certainty exists about the role of nutrition in the etiology of cancer, many facts in favor of the relationship became available during the last decades. Correlation studies, experimental work and to a lesser extent case-control studies made it possible to clarify the role of certain nutrients and foods in carcinogenesis. The most important cancer sites where nutrition could play a role are esophagus, stomach, colon, rectum, prostate and breast. Esophageal cancer is of a very complex etiology, in which alcohol intake plays an important role, at least in western countries. The cancer-promoting properties of alcohol intake are enhanced by smoking. Three factors from nutrition are probably related to stomach cancer, namely salt, nitrate/nitrite and vitamin C. Salt is caustic to the stomach mucosa, resulting in atrophic gastritis. Salt is also co-carcinogenic and stomach cancer-promoting in experimental animals. Nitrate is probably important at the stage of atrophic gastritis, where bacterial overgrowth, due to the high pH, converts nitrates in nitrites, making the loco synthesis possible of potent nitrosocarcinogens. Vitamin C inhibits the latter step. The epidemiological evidence for the role of those factors is provided. The most important among them is the strong and consistent association of stomach cancer mortality with stroke. Rectum, colon, prostate and breast cancer are related in some way to fat intake. They all seem positively related to saturated fat intake, whereas breast cancer is probably also promoted by polyunsaturated fat intake. However, polyunsaturated fat seems to be without effect on rectum cancer. Colon and prostate cancer are probably also influenced by polyunsaturated fat but to a lesser degree than breast cancer. An important argument for this are the positive ecological correlations between changes in rectum, colon and breast cancer mortality from 1968 on, and changes occurring in coronary heart diseases, stroke and diabetes mortality. Those six types of mortality are decreasing, or only slightly increasing in the USA, Belgium, France, the Netherlands, etc. They are strongly increasing in East European countries. The intake of saturated fat has generally decreased in the first group of countries, and has markedly increased in the second group.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Nutrition and cancer. 353 16


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