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

Genetic and epigenetic alterations in oncogenes, tumor suppressor genes, cell adhesion molecules, telomere and telomerase activity as well as genetic instability at several microsatellite foci are responsible for multistep process of human stomach carcinogenesis. The scenario of these alterations found in gastric cancer differs depending on the two histological types, indicating that different genetic pathways exist for well differentiated or intestinal type and poorly differentiated or diffuse type gastric cancers, even though both types of gastric cancer may arise from epithelial "stem cells" which express human telomerase reverse transcriptase (hTRT) and telomerase activity. Infection with Helicobacter pylori, which evidently causes the release of reactive oxygen species (ROS) and reactive nitrogen species (RNS), may be a strong trigger for "stem cell" hyperplasia in intestinal metaplasia, followed by telomere reduction and increase telomerase activity as well as hTRT overexpression. They may precede DNA replication error, DNA hypermethylation, CD44 abnormal transcript and p53 mutations, all of which occur in at least 30% of intestinal metaplasia as early events of multistep pathogenesis of well differentiated type gastric cancer.
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PMID:Molecular mechanism of human stomach carcinogenesis implicated in Helicobacter pylori infection. 978 10

Helicobacter pylori gastritis (i.e. H. pylori infection and complications) is a focus of tremendous research activity today. Besides peptic ulcer disease, a large number of reports suggest that other diseases are associated with H. pylori. The International Agency for Research on Cancer sponsored by the World Health organization classified the bacterium as a group I carcinogen in 1994. Population-based studies of H. pylori and gastric cancer in 1991 showed an increased odds ratio, of 3-6, in infected patients, and a calculation of odds ratios in different age groups showed a markedly increased odds ratio, to about 20, in younger ages. Studies of non-ulcer dyspepsia and the effect of cure of H. pylori show either none, small, or significant symptom relief, suggesting a positive effect in a subgroup of non-ulcer dyspepsia patients. Mucosa-associated lymphoid tissue-lymphoma caused by H. pylori could be eradicated, at least in its mild forms. Barrett's ulcer is a possible H. pylori-associated disease as well as gastroesophageal reflux disease. Normal feedback in the acid regulation system is changed in infected patients, which may facilitate an increased gastroesophageal acidic reflux. Gastropathy and/or peptic ulcer due to use of nonsteroidal antiinflammatory drugs is probably aggravated by the infection. The infectious disease H. pylori gastritis is associated with a large number of complications, some of which are serious. There are no data showing any advantages of the infection. Giving anti-H. pylori therapy to infected patients should be regarded as essential.
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PMID:Are there more clinically important complications of Helicobacter pylori infection than peptic ulcer disease? A review of current literature. 984 18

Helicobacter pylori (H. pylori) infection leads to profound changes in gastric physiology. Several clinical and animal studies have been performed to clarify the influence of H. pylori on gastric acid secretion. Published data, however, are not consistent throughout. Infection of the gastric antrum, which can be observed mainly in duodenal ulcer patients, increases gastrin release and consecutively acid output. The net effect of corpus and antrum gastritis, such as in patients with gastric cancer, is to decrease acid secretion. Chronic H. pylori infection may finally promote gastric atrophy with irreversibly diminished acid secretion but in earlier stages of this infection eradication of H. pylori normalizes gastric secretory activity.
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PMID:[Helicobacter pylori and gastric acid secretion]. 1019 Feb 51

Cancer of the distal stomach, both of the intestinal and diffuse type, is strongly associated with Helicobacter pylori colonization. This bacterium causes chronic active inflammation of the gastric mucosa in the majority of colonized subjects. In a considerable number of them, this will eventually lead to a loss of gastric glands, and thus the establishment of atrophic gastritis, which is associated with the development of intestinal metaplasia and dysplasia. Development of atrophy and metaplasia of the gastric mucosa are thus strongly associated with H. pylori infection, instead of a direct and inevitable consequence of ageing. Approximately 40-50% of infected subjects develop these conditions, but they are rare in non-infected subjects. The presence of these consecutive disorders leads to a 5-90-fold increased risk for cancer of the distal stomach, in particular of the intestinal type. This sequence explains the increased risk for gastric cancer in H. pylori-infected subjects, as has been shown in various cross-sectional and longitudinal studies. In a combined analysis of three longitudinal studies, a significant trend was observed towards an increased odds ratio with longer intervals between (retrospective) serological diagnosis of H. pylori infection and observation of gastric cancer, this risk being more than eight-fold increased if the interval had been at least 15 years. This is thought to reflect development of atrophic gastritis and intestinal metaplasia with loss of H. pylori colonization in the years prior to development of cancer. Atrophic gastritis and gastric cancer thus appear closely associated with the presence of H. pylori, yet not all infected subjects will eventually develop atrophy and only a small minority develop gastric cancer. Factors that influence the risks for atrophy and cancer in the presence of infection may be related to the time that infection occurred and to characteristics of the bacterial strain and the host. Evidence for the role of these factors is now increasing. Recognition of the causal role of H. pylori in the induction of gastric cancer theoretically presents tools for cancer prevention. The efficacy of screening and bacterial eradication for prevention of distal gastric cancer is being studied in a number of large-scale intervention studies in different populations. It is hoped that these studies will also provide answers to the potential preventive role of H. pylori colonization in the development of gastro-oesophageal reflux disease and associated conditions, in particular development of cancer of the proximal stomach. Infection with H. pylori plays an important role in the aetiology of atrophic gastritis and gastric cancer. Studies suggest an eight-fold increased risk for both conditions in the presence of infection. Factors that influence the risk for both conditions in the presence of infection are the age at which infection occurred and the presence of cagA as a marker for more pathogenetic H. pylori strains. The efficacy and side-effects of intervention for the prevention of distal gastric cancer has yet to be established.
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PMID:Review article: exploring the link between Helicobacter pylori and gastric cancer. 1020 81

Infection with Helicobacter pylori is now recognized as the primary cause of peptic ulcers and their recurrence. Compelling evidence has also been found linking H. pylori infection to gastric cancer, the second most common cancer in the world. Given the high rate of patient morbidity and mortality associated with gastric cancer, any method by which one can reduce the occurrence of the disease or increase its early detection is desirable. The strong correlation with H. pylori infection and the current availability of easily administered tests for the detection of the pathogen argue for screening at least those individuals with a family history of gastric cancer or other risk factors. This article reviews the association between H. pylori and gastric cancer and the pathologic changes that the infection produces in the gastric mucosa, as well as the cost-effectiveness of universal testing and eradication of the infection in H. pylori-positive individuals to reduce gastric cancer.
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PMID:Helicobacter pylori and gastric cancer. 1062 41

Infection with the bacterium Helicobacter pylori is associated epidemiologically with development of gastric cancer. To better understand the role of H. pylori in carcinogenesis, we examined the effects of H. pylori on cell cycle-related events in the AGS gastric cancer cell line. During coculture, wild-type, toxigenic, cagA-positive H. pylori induced both apoptosis and inhibition of cell cycle progression at G1-S in AGS cells. These effects were most apparent in AGS cells synchronized by serum-deprivation and then stimulated to progress through the cell cycle by refeeding. An isogenic cagA-negative mutant H. pylori, produced similar effects. In contrast to changes induced by 5-fluorouracil, the inhibition of cell cycle progression from G1 to S caused by H. pylori was not accompanied by sustained changes in p53 or p21cip1, but was associated with reduced expression of p27kip1 and inhibition of transcriptional activation of the serum-response element of c-fos. Our results indicate that H. pylori inhibits cell cycle progression at G1-S and induces apoptosis, associated with reduced expression of p27kip1 in AGS gastric cancer cells. In vivo, similar effects as a result of H. pylori infection may lead to potentially deleterious compensatory hyperproliferation by nonneoplastic gastric epithelial cells.
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PMID:Helicobacter pylori inhibits the G1 to S transition in AGS gastric epithelial cells. 1034 28

Gastritis caused by infection with Helicobacter pylori (H. pylori) is one of the most common infectious diseases worldwide. There are data on the epidemiology, pathophysiology, and histology of this disease that show that H. pylori gastritis has an important role in gastric carcinogenesis. However, it has to be considered that only very few of those infected with H. pylori will develop gastric cancer. Hence, it will be a main target of future research to identify individuals who carry a greater risk for developing gastric cancer, and therefore may benefit from eradication of H. pylori in terms of gastric cancer prevention.
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PMID:Helicobacter pylori and Gastric Cancer. 1038 94

Infection with Helicobacter pylori has been associated with an increased risk of gastric cancer in low-risk populations. However, our previous results (P. M. Webb et al., Int. J. Cancer, 67: 603-607, 1996) from an ongoing prospective study in Shanghai, China, a relatively high-risk population, failed to show an association between H. pylori infection and the subsequent risk of gastric cancer. That previous study had a relatively short time period of follow-up and the enzyme-linked immunosorbent assay (ELISA) used was based on strains found in Southern England and without validation among the Chinese. Either one of these two factors could have had an impact on the validity of those earlier observations. An ELISA developed and validated among Shanghai residents was used in the present study to reexamine specific antibodies to H. pylori in 188 gastric cancer patients and 548 control subjects. All of the cases of gastric cancer were identified during the first 12 years of follow-up of a cohort of 18,244 men, ages 45-64 years in Shanghai, from whom blood samples were collected at enrollment during 1986-1989. For each cancer case, three cancer-free control subjects were randomly selected from the cohort and matched to the index cases by age (within 2 years), month and year of sample collection, and neighborhood of residence. The Shanghai-based ELISA detected a higher prevalence of serum antibodies to H. pylori than the English-based assay in both gastric cancer cases (86 versus 53%) and control subjects (85 versus 56%). Virtually all of the subjects (98%) who were H. pylori-seropositive by the English-based assay tested positive by the Shanghai-based assay. On the other hand, 73% of gastric cancer cases and 68% of control subjects who were seronegative according to the English-based assay tested positive by the Shanghai-based assay. Using this alternative assay, combined with increased follow-up, our latest data contradict our earlier findings and show a statistically significant association between H. pylori seropositivity and gastric cancer risk (odds ratio, 1.84; 95% confidence interval, 1.08-3.11). We noted an increasing rate of seropositivity among cases as the time interval between cohort enrollment and cancer diagnosis increased. Among subjects followed for 5 or more years after enrollment, the odds ratio for gastric cancer related to H. pylori seropositivity was 3.74 (95% confidence interval, 1.51-9.30).
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PMID:Helicobacter pylori infection and risk of gastric cancer in Shanghai, China: updated results based upon a locally developed and validated assay and further follow-up of the cohort. 1042

With an aim of promoting primary prevention of cancer, major avoidable risk factors as well as protective factors of cancer are reviewed based on previous epidemiological studies. Among various risk factors of cancer, tobacco is the most important avoidable risk factor for cancers of the oral cavity, larynx, lung, pharynx, esophagus, stomach, liver, pancreas, kidney (pelvis), ureter, bladder, and cervix. Tobacco accounts for some 20-30% of all sites of cancer. Betel quid and tobacco chewing is an important risk factor for cancer of the oro-pharynx in some parts of South-East Asia. Diet also plays an important role in the etiology of cancer, but its relation to cancer is complicated. An excess or insufficient intake of some food components elevates risk of cancer of several sites. Eating habits, available foods, methods of food processing may vary from country to country. Infection of oncogenic viruses (especially, HBV, HVC, HPVs) is an important avoidable risk factor of cancer where liver cancer and cervical cancer are common. Infection of Helicobacter pylori could also be an important risk factor of stomach cancer. Attributable risks of other avoidable risk factors, such as occupation, environmental pollution, sun light, radiation, food additives, pesticides, drugs, etc. are relatively small compared to those of tobacco, diet and infection. Exercise and stress are also manageable risk factor of cancer.
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PMID:Major avoidable risk factors of cancer. 1054 92

Helicobacter pylori infects more than half of the world's population, making it one of the most prevalent infections. H pylori is now accepted as the most common cause of histologic gastritis and is responsible for the majority of cases of peptic ulcer disease and gastric cancer. Approximately 1 in 6 (17%) persons with H pylori infection will develop peptic ulcer disease, and each year 1% to 2% of these will experience a major or life-threatening complication, such as bleeding, perforation, or gastric outlet obstruction. Peptic ulcer disease should no longer be regarded as a chronic, recurring, lifelong disease, but rather as a curable infectious disease. The diagnosis and therapy of this common infectious disorder have become increasingly straightforward. In this article, we discuss the possible outcomes of long-standing infection, the various diagnostic tests available, including whom and when to test, and the combination drug regimens approved for cure.
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PMID:Diagnosis and management of Helicobacter pylori infection. 1068 79


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