When heredity is infectious

Bacteria and mucosal inflammation of the gut: lessons from Helicobacter pylori

The human gastrointestinal tract is colonized by an abundance of bacteria, which are in constant interaction with the epithelial lining usually leading to an intricate balance between tolerance and immunological response. There is ample evidence that the abundant presence of bacteria thus plays a role in the maintenance of human health, as well as in the induction of chronic inflammatory diseases of the gastrointestinal tract. Research in this field is, however, considerably hampered by the abundance of bacterial species, many of which have not even been characterized, and are difficult to culture specifically. These important limitations may to some extent be overcome by recent molecular biologic methods. Furthermore however, the adherent mucosal flora may differ largely from the luminal flora and that in excreta. These characteristics do not pertain to Helicobacter pylori, which generally colonizes the human stomach as a single strain with stable characteristics. Such colonization is stable throughout life, but can be treated. Furthermore, the association with chronic gastritis is very strong. For these reasons, H. pylori serves as an excellent model for the understanding of the processes involved in bacterial colonization and host response including mediation of immunoregulation, and the mechanisms by which this response can lead to disease.

Gastric cancer: new genetic developments

Gastric cancer's (GC) incidence shows large geographic differences worldwide with the lowest rates occurring in most Western industrialized countries including the United States and the United Kingdom; in contrast, relatively high rates of GC occur in Japan, Korea, China, and South America, particularly Chile. The Laurén classification system classifies GC under two major histopathological variants: 1) an intestinal type and 2) a diffuse type. The intestinal type is more common in the general population, more likely to be sporadic and related to environmental factors such as diet, particularly salted fish and meat as well as smoked foods, cigarette smoking, and alcohol use. It exhibits components of glandular, solid, or intestinal architecture, as well as tubular structures. On the other hand, the diffuse type is more likely to have a primary genetic etiology, a subset of which, known as hereditary diffuse gastric cancer (HDGC), is due to the E-cadherin (CDH1) germline mutation. The diffuse type pathology is characterized by poorly cohesive clusters of cells which infiltrate the gastric wall, leading to its widespread thickening and rigidity of the gastric wall, known as linitis plastica. Helicobacter pylori infection is associated with risk for both the intestinal and diffuse varieties of gastric cancer. Germline truncating mutations of the CDH1 gene, which codes for the E-cadherin protein, were initially identified in three Maori families from New Zealand that were predisposed to diffuse GC. Since then, similar mutations have been described in more than 40 additional HDGC families of diverse ethnic backgrounds. It is noteworthy that two-thirds of HDGC families reported to date have proved negative for the CDH1 germline mutation. A number of candidate genes have been identified through analysis of the molecular biology of E-cadherin. Patients with evidence of the CDH1 germline mutation in the context of a family history of HDGC must be considered as candidates for prophylactic gastrectomy, given the extreme difficulty in its early diagnosis and its exceedingly poor prognosis when there is regional or distant spread. Specifically, the E-cadherin cytoplasmic tail interacts with catenins, assembling the cell-adhesion complex involved with E-cadherin mediated cell:cell adhesion. Beta-catenin and gamma-catenin compete for the same binding site on the E-cadherin cytoplasmic tail, directly linking the adhesion complex to the cytoskeleton through alpha-catenin. Beta-catenin gene (CTNNB1) mutations have been described predominantly in intestinal-type gastric cancers and CTNNB1 gene amplification and overexpression have recently been described in a mixed-type gastric cancer. This paper reviews the genetics of both intestinal and diffuse types of gastric carcinoma, their differential diagnosis, molecular genetics, pathology, and, when known, their mode of genetic transmission within families.

Helicobacter pyloriet cancer gastrique

Gastric cancer is a worldwide cancer especially frequent in Japan and South America. This cancer affects 10 to 70 people per 100,000 according to the countries. Since the end of the Second World War, the incidence of gastric cancer has been decreasing in France and accounts for less than 10 % of mortality. Helicobacter pylori infection, host genetic background, food regimen are known to be involved in this cancer. Helicobacter pylori should be eradicated in selected patients, such as patients' relatives with documented gastric cancer as well as patients having another gastrointestinal cancer.

Is there a link between environmental factors and a genetic predisposition to cancer? A lesson from a familial cluster of gastric cancers

To determine the prevalence of gastric precancerous lesions and mucosal genetic alterations in relatives of a cluster of familial gastric cancer (FGC), we studied a kindred spanning two generations. The founder, daughter and niece underwent surgery for gastric cancer (GC); a son and other two daughters of the founder, presented with chronic dyspepsia. In all subjects, gastric mucosa samples were analysed for pathological features, Helicobacter pylori infection, microsatellite (MIN) and chromosomal (CIN) instability. The overexpression of mp53 and c-myc, and cytoplasmic beta-catenin delocalisation were found in the 2 younger cancer patients. All GC and gastritis patients had normal E-cadherin expression and were MIN-negative. Aneuploidy characterised all GC cases, and mixed euploid and aneuploid cell populations were present in the gastric biopsies from two of three 'at-risk' relatives. These two subjects, one of whom had severe active gastritis, and gastric mp53 and c-myc expression, were CagA-positive H. pylori-infected. DNA aneuploidy, p53 and c-myc expression disappeared after H. pylori eradication. In this FGC cluster, genetic abnormalities were found in first-degree relatives (3 patients) only in presence of H. pylori infection (2 cases H. pylori-positive versus 1 case H. pylori-negative) supporting the hypothesis that, besides the influence of a genetic profile, FGC may be, at least partly, mediated by intrafamilial clustering of H. pylori infection.

Family history of gastric cancer: should we test and treat for Helicobacter pylori?

A close link has been established between infection and gastric cancer. In this article, we suggest that using a risk stratification technique (like that for colorectal cancer), the high-risk group of first-degree relatives of patients with gastric cancer can be separated out for testing and treatment. This would be more manageable and more cost-effective than screening the whole population, in which the mortality from distal gastric cancer has declined concomitant with the eradication of infection. Support for the feasibility of this approach is derived from studies showing that the family is the core unit of transmission and that childhood colonization, especially with a virulent strain, is apparently a major risk factor for disease progression to the neoplastic stage. When there is a case of gastric cancer in the family, first-degree relatives, who might be infected by a bacterium with an identical genetic fingerprint, are at higher risk than normal for developing gastric cancer. Furthermore, genetic and epidemiologic studies based on the Correa model have shown that both primary and secondary prevention of gastric cancer is possible. Calculations done in high-risk populations, such as Japanese-Americans, confirm the savings in cost and the safety of the test-and-treat strategy. Considering that eradication should be done as early as possible, at a point in the cascade when the changes are still reversible, and that gastric cancer is associated with a high mortality rate, we suggest that this strategy be applied to this high-risk population.

Review article: Helicobacter pylori and gastric adenocarcinoma

Gastric adenocarcinoma is still the second most common cause of death from cancer, even though it is on the decline in developed countries. Although H. pylori gastritis appears to be a necessary antecedent to the development of gastric adenocarcinoma, it is not a sufficient factor in and of itself. Other required factors for the progression of this disease are poorly understood. Patients with antral predominant gastritis seem protected from the disease, while patients with pangastritis are predisposed to both diffuse- and intestinal-type adenocarcinoma. Development of a vaccine against H. pylori might yield promising results in decreasing the incidence of gastric adenocarcinoma.

Current concepts in the management of Helicobacter pylori infection--the Maastricht 2-2000 Consensus Report

Significant progress and new insights have been gained in the 4 years since the first Maastricht Consensus Report, necessitating an update of the original guidelines. To achieve this, the European Helicobacter Pylori Study Group organized a meeting of specialists and experts from around the world, representatives from National Gastroenterology Societies and general practitioners from Europe to establish updated guidelines on the current management of Helicobacter pylori infection. The meeting took place on 21-22 September 2000. A "test and treat" approach is recommended in adult patients under the age of 45 years (the age cut-off may vary locally) presenting in primary care with persistent dyspepsia, having excluded those with predominantly gastro-oesophageal reflux disease symptoms, non-steroidal anti-inflammatory drug users and those with alarm symptoms. Diagnosis of infection should be by urea breath test or stool antigen test. As in the previous guidelines, the eradication of H. pylori is strongly recommended in all patients with peptic ulcer, including those with complications, in those with low-grade gastric mucosa-associated lymphoid tissue lymphoma, in those with atrophic gastritis and following gastric cancer resection. It is also strongly recommended in patients who are first-degree relatives of gastric cancer patients and according to patients' wishes after full consultation. It is advised that H. pylori eradication is considered to be an appropriate option in infected patients with functional dyspepsia, as it leads to long-term symptom improvement in a subset of patients. There was consensus that the eradication of H. pylori is not associated with the development of gastro-oesophageal reflux disease in most cases, and does not exacerbate existing gastro-oesophageal reflux disease. It was agreed that the eradication of H. pylori prior to the use of non-steroidal anti-inflammatory drugs reduces the incidence of peptic ulcer, but does not enhance the healing of gastric or duodenal ulcer in patients receiving antisecretory therapy who continue to take non-steroidal anti-inflammatory drugs. Treatment should be thought of as a package which considers first- and second-line eradication therapies together. First-line therapy should be with triple therapy using a proton pump inhibitor or ranitidine bismuth citrate, combined with clarithromycin and amoxicillin or metronidazole. Second-line therapy should use quadruple therapy with a proton pump inhibitor, bismuth, metronidazole and tetracycline. Where bismuth is not available, second-line therapy should be with proton pump inhibitor-based triple therapy. If second-line quadruple therapy fails in primary care, patients should be referred to a specialist. Subsequent failures should be handled on a case-by-case basis by the specialist. In patients with uncomplicated duodenal ulcer, eradication therapy does not need to be followed by further antisecretory treatment. Successful eradication should always be confirmed by urea breath test or an endoscopy-based test if endoscopy is clinically indicated. Stool antigen test is the alternative if urea breath test is not available.

Family history of cancer and risk of esophageal and gastric cancers in the United States

The worldwide rates for histology- and subsite-specific types of esophageal and gastric cancer reveal strikingly divergent patterns. The contribution of environmental and genetic factors has been explored in several high-incidence areas, but data on genetic influences are scarce for Western countries. Using data from a multicenter, population-based, case-control study on 1,143 cases and 695 controls in the United States, we evaluated whether a family history of digestive or other cancers was associated with an increased risk of esophageal adenocarcinoma (n = 293), esophageal squamous cell carcinoma (n = 221), gastric cardia adenocarcinoma (n = 261) or non-cardia gastric adenocarcinoma (n = 368). After adjusting for other risk factors, individuals reporting a family history of digestive cancers experienced no increased risk of either type of esophageal cancer but they were prone to adenocarcinomas of the gastric cardia [odds ratio (OR) = 1.34, 95% confidence interval (CI) 0.91-1.97] and non-cardia segments (OR =1.46, 95% CI 1.03-2.08). This familial tendency, particularly for non-cardia gastric tumors, was largely explained by an association with family history of stomach cancer (OR = 2.52, 95% CI 1.50-4.23). In addition, family history of breast cancer was associated with increased risks of esophageal adenocarcinoma (OR = 1.74, 95% CI 1.07-2.83) and non-cardia gastric adenocarcinoma (OR = 1.76, 95% CI 1.09-2.82). Also seen were non-significant familial associations of esophageal squamous-cell cancer with prostate cancer as well as non-cardia gastric cancer with leukemia and brain tumors, though these relationships must be interpreted with caution. Our data point to the role of familial susceptibility to gastric cancer, but not to any form of esophageal cancer, in the United States.

Advantages and disadvantages of population screening for cancer and surveillance of at-risk groups

Despite improvements in diagnostic and therapeutic modalities, the prognosis of patients with gastrointestinal malignancies has remained poor. In essence, this poor outcome is related to the majority of patients presenting at an already advanced stage of disease at the time of diagnosis. Unfortunately, however, mass screening and surveillance programmes aimed at early detection and treatment in the population at large are in most countries considered to be cost-ineffective. Moreover, even with regard to established risk groups, there is considerable debate over whether current surveillance strategies are beneficial to these patients in terms of a reduction in cancer-related mortality. This chapter addresses various aspects of screening and surveillance. In the first part, general issues are discussed, whereas the second part focuses particularly on disease entities frequently encountered in gastrointestinal practice.

Is Helicobacter pylori infection in childhood a risk factor for gastric cancer?

Helicobacter pylori infection is associated with chronic gastritis and peptic ulcer disease. Furthermore, the World Health Organization has classified this organism as a carcinogen for gastric cancer. H pylori infection is mainly acquired in childhood. Children with H pylori infection are asymptomatic except for a very small number that develop peptic ulcer disease. However, if H pylori gastritis is associated with gastric cancer, do pediatricians need to screen children for this infection and treat those who are infected? In an attempt to determine the significance of the association between H pylori and gastric cancer, we have reviewed all of the English language literature on this topic. H pylori infection seems to be associated with an increased risk of developing gastric cancer. However, only a small number of infected individuals (~1%) will develop gastric cancer. Furthermore, there are potential cofactors other than H pylori that could be equally important. The effect of the eradication of H pylori alone on the development of gastric cancer is unknown. Based on our knowledge to date, we suggest that it is not indicated to treat all children with H pylori infection because of the risk of developing gastric cancer or to institute a screening and treatment program.

Genetic factors in the development of gastric precancerous lesions--a role of Helicobacter pylori ?

Helicobacter pylori is believed to predispose to gastric cancer by inducing gastric precancerous alterations. There is a well known predisposition to gastric cancer and the risk of developing it is greater in relatives of patients with familial cases of this malignancy. The aim of this study was to determine the prevalence of gastric precancerous lesions (atrophy and intestinal metaplasia) and their association with Hp infection in first-degree relatives in patients with noncardia gastric cancer.

METHODS

Hp status and gastric histology assessed by upper gastrointestinal endoscopy, biopsies from the antral and body region, the rapid urease test and staining for Hp, inflammation, activity, atrophy and intestinal metaplasia (prevalence and grading) were studied in 108 first-degree relatives of patients with noncardia gastric cancer and compared with 73 controls with mild non-ulcer dyspepsia who had no cancer relatives and were examined in the same way.

RESULTS

subjects with and without cancer relatives had a similar prevalence of Hp infection (49 vs. 47%). Endoscopy revealed a few asymptomatic duodenal ulcers and small hiatus hernias in Hp positive subjects of both groups. Hp positive relatives of gastric cancer had a markedly higher prevalence of atrophy than those with Hp negativity without cancer relatives (29 vs. 9%) and those with Hp negativity and cancer relatives (29 vs. 3%. Prevalence of intestinal metaplasia was also higher in those with Hp positivity and cancer relatives than in those without cancer relatives (15 vs. 5% and was not present in Hp negative subjects with cancer relatives. Inflammation and activity showed similar scores in subjects with and without cancer relatives with higher scores in both Hp positive groups. The prevalence of precancerous lesions in the relatives of gastric cancer was nearly always confined to those with Hp positivity. One year after eradication the prevalence of atrophy in cancer relatives decreased from 29 to 14%; prevalence of intestinal metaplasia remained without substantial changes. Scores for inflammation and activity were also lower after eradication.

CONCLUSIONS

First-degree relatives of patients with gastric cancer have an increased prevalence of gastric precancerous abnormalities which are strongly confined to those with Hp infection. Eradication of Hp in these subjects with cancer relatives reduces the prevalence of precancerous lesions (atrophy) and grades of inflammation and activity. In view of these results, eradication of Hp should be offered to such subjects.