Helicobacter pylori and gastric cancer prevention is possible

Overview of Infectious Causes of Human Cancers

Emerging evidence has demonstrated that almost each person is infected at least one potentially cancer-causing organism; however, only a small proportion of infected individual develops cancer. In this review, to elucidate the potential role of infectious organisms in the development and progression of human cancers, we summarize the previous history and current understandings of infection-associated cancers and highlight the common molecular mechanisms of cancers caused by infectious agents and their potential cofactors, which may bring us to effectively prevent and reduce the infection-associated cancers in the future.

Helicobacter pylori infection predicts favorable outcome in patients with gastric cancer

BACKGROUND

Recent studies have suggested a controversial role of Helicobacter pylori infection in gastric cancer prognosis. The aim of the present study was to investigate the potential impact of H. pylori status on the prognosis of patients with gastric cancer in a Chinese prospective cohort.

METHODS

Between 2007 and 2009, 261 patients with curatively resected gastric cancer were enrolled in the study. H. pylori status was defined by means of immunohistochemical staining in tumour and non-neoplastic tissues. Treatment prognosis was measured in terms of cancer-specific survival and disease-free survival (dfs). Univariate and multivariate Cox regression models were used to assess the association between H. pylori status and patient prognosis.

RESULTS

Positivity for H. pylori infection was observed in 188 of the 261 patients (72.0%). In patients positive for H. pylori, mean cancer-specific survival was 55.2 months [95% confidence interval (ci): 53.4 to 56.9 months] and mean dfs was 53.9 months (95% ci: 51.8 to 56.0 months); the same survivals were, respectively, 45.1 months (95% ci: 42.2 to 47.9 months) and 43.7 months (95% ci: 40.4 to 47.0 months) in patients negative for H. pylori. In univariate analysis, positive H. pylori status was associated with better cancer-specific survival [hazard ratio (hr): 0.486; 95% ci: 0.271 to 0.870; p = 0.015] and dfs (hr: 0.540; 95% ci: 0.307 to 0.950; p = 0.033). In multivariate analysis, H. pylori was an independent prognostic factor for cancer-specific survival (hr: 0.485; 95% ci: 0.265 to 0.889; p = 0.019).

CONCLUSIONS

Our study demonstrates that positive H. pylori status is a beneficial prognostic indicator in patients with gastric cancer and might suggest possible therapeutic approaches for gastric cancer. Further research is required to better understand inflammation mechanisms and cancer progression.

Mitochondrial microsatellite instability in gastric cancer and gastric epithelial dysplasia as a precancerous lesion

BACKGROUND

Genetic instability in gastric cancer represents a key molecular step that occurs early in the carcinogenesis process. To clarify the role of genetic instability in the progression from gastric dysplasia to gastric cancer, mitochondrial microsatellite instability (mtMSI) was studied in gastric cancer and gastric dysplasia.

METHODS

DNA was isolated from paired normal and tumoral tissues in 24 patients with gastric dysplasia (low grade) and 49 patients with gastric cancer. mtMSI was analyzed using eight microsatellite markers. mtMSI in gastric dysplasia was studied prospectively to elucidate the relation between mtMSI and gastric carcinogenesis.

RESULTS

mtMSI was found in 5 (10.2%) of 49 gastric cancer patients. The mtMSI phenotype was not associated with age, gender, and Helicobacter pylori infection. However, all of the mtMSI was found in intestinal-type gastric cancer (20.8%, p=0.02). In gastric dysplasia, mtMSI was detected in 3 (12.5%) of 24 patients with gastric dysplasia. mtMSI-positive gastric dysplasia showed a poor prognosis statistically compared to mtMSI negative through progression to high-grade dysplasia or gastric cancer.

CONCLUSIONS

These data suggest that mtMSI may be an early and important event in the progression of gastric carcinogenesis, especially in intestinal-type gastric cancer.

Autoimmune responses induced by Helicobacter pylori improve the prognosis of gastric carcinoma

Gastric carcinoma (GC) remains one of most serious malignant tumors worldwide, with Helicobacter pylori being the definite carcinogen. The H. pylori components, cytotoxin-associated gene A (CagA), vacuolating toxin A (VacA) and blood-group antigen-binding adhesin gene (BabA), can mimic and bind to specific receptors or surface molecules both on gastric epithelial cells and platelets, in which CagA and VacA may also be directly involved in loosening of tight junctions in monolayers of polarized gastric epithelial cells. It has been shown that a history of H. pylori infection is found in the majority of patients with GC, and that anti-CagA, anti-VacA and anti-BabA antibodies targeting both H. pylori components and host mimic molecules can be detected in them with increased levels. Patients with GC who are positive for H. pylori prospectively have a better outlook than those negative. The stimulation of mentioned autoantibodies in antigen processing and presentation and subsequent T-cell activation and proliferation improves host immune status. On the other hand, in an autoimmune response, autoantibodies can induce the cross-reaction against those localized or circulating GC cells, which are characterized by mimic or absorbed H. pylori antigens, and lead to the killing and even suppressing of metastasis of cancer cells. Therefore, we here hypothesize that autoimmune responses induced by H. pylori components may play a key role in improving the prognosis of patients with gastric carcinoma.

[Helicobacter pylori infection and eradication are not related to glycosylated hemoglobin levels (HbA1c) in young patients with type 1 diabetes]

OBJECTIVE

Helicobacter pylori (Hp) is a chronic stomach infection common throughout the world. The pediatric diabetes literature on the relation between Hp and HbA1c is sparse and controversial. This study aimed to investigate this relation.

METHODS

The study included 100 youth with type 1 diabetes and seropositive for Hp (European Caucasians: n=49; Moghrabin Caucasians: n=51). Mean socioeconomic status was lower among the latter. Hp infection was demonstrated by the (13)C-urea breath test and a gastric biopsy for antibiotic susceptibility testing. HbA1c levels were measured for a year (mean: 6 measurements; upper normal limit: 6.2%) before and after Hp eradication, which was proved by the (13)C-urea breath test.

RESULTS

Of 100 Hp-seropositive patients, 49 had active Hp infections and were treated. Mean age+/-SD was 14.2+/-2.8 years, and duration of diabetes at Hp diagnosis was 6.2 +/-2.3 years. Hp infection was eradicated in 38/49 subjects (78%). Eleven (22%) remained infected and required a second treatment. The two subgroups did not differ for age, duration of diabetes or pretreatment HbA1c levels (7.3+/-1.5% versus 7.8+/-0.8%; p=0.16). Mean HbA1c levels in the 49 infected subjects did not differ significantly in the year before and after eradication (7.4+/-1.3% versus 7.9+/-1.1%; p=0.08). Prevalence of infection was higher among youth of North African than European ancestry (47% versus 22%; p<0.001). Their HbA1c levels, however, did not differ (7.3+/-1.5% versus 7.7+/-0.9%; p=0.31), nor did age or duration of diabetes. Among the 100 Hp-seropositive patients, vague abdominal pain was reported by 45 of them; only 24 had active Hp infections.

CONCLUSION

Before treatment, patients seropositive for Hp did not differ in HbA1c levels or abdominal complaints according to whether they had active Hp infection. Hp infection was twice as frequent in Moghrabin Caucasians than in European Caucasians, perhaps associated with their lower socioeconomic status. HbA1c levels were similar in patients with and without Hp eradication after one treatment. After a one-year follow-up, Hp eradication had no significant effect on HbA1c levels.

Asymptomatic Helicobacter pylori infection and iron deficiency are not associated with decreased growth among Alaska Native children aged 7-11 years

INTRODUCTION

Alaska Native children have high Helicobacter pylori infection and iron deficiency prevalences, and their average height-for-age is lower than US reference populations. During a clinical trial to determine the impact of H. pylori treatment on iron deficiency, we evaluated the effects of H. pylori infection and treatment on growth.

MATERIALS AND METHODS

We measured height and weight for children aged 7-11 years in western Alaska using village-based measuring devices. H. pylori infection was determined by urea breath test and iron deficiency using serum ferritin. Children with H. pylori infection and iron deficiency entered the treatment phase and received iron alone or iron plus triple therapy for H. pylori. Follow-up evaluations occurred at 2, 8, and 14 months. We evaluated the association between baseline H. pylori infection and growth; among children in the treatment phase, we also assessed the effect of H. pylori resolution on growth.

RESULTS

At baseline, 566 (87.1%) of 650 children were infected with H. pylori. Neither height and weight, nor body mass index differed by H. pylori infection status. Of 189 children in the treatment phase, 20 (10.6%) were uninfected at all three follow-up periods, and 54 (28.6%) were uninfected for one or two periods. Compared with continuously infected children, children in these two groups had little evidence of improvements in any of the measured growth outcomes.

CONCLUSIONS

H. pylori infection is not related to growth among Alaska Native children aged 7-11 years. Growth deficiency should not be considered an indication for H. pylori therapy.