Shinobu Imagawa

Clinical prevention of gastric cancer by Helicobacter pylori eradication therapy: a systematic review

Helicobacter pylori (H. pylori) infection plays an important role in gastric carcinogenesis. We conducted a systematic review concerning gastric cancer development after H. pylori eradication therapy. In total 15 papers matched our criteria, the results were reviewed. The H. pylori eradication therapy statistically diminished the prevalence of clinical gastric cancer by approximately one-third. The studies from Japan supported this conclusion; however, studies from overseas reported conflicting results. The differences in these conclusions lie in the diagnostic ability of endoscopic examination, since the clinical stage was quite different between these studies. Gastric cancer that developed after eradication revealed a mainly intestinal type histology and depressed-type appearance. The following are possible reasons for reduced gastric cancer: (1) eradication therapy inhibits the new occurrence of gastric cancer, (2) eradication regresses or inhibits the growth of gastric cancer, and (3) eradication interferes with the discovery of gastric cancer. Considering the biological nature of cancer cell proliferation, a sufficiently long-term follow-up may clarify the effect of eradication therapy on inhibition of the development (not discovery) of gastric cancer and reduction of gastric cancer-related mortality.

Morphological changes in human gastric tumours after eradication therapy of Helicobacter pylori in a short-term follow-up

Background : It is controversial as to whether the development of gastric cancer is influenced by Helicobacter pylori eradication. If eradication itself influences the tumour morphology, this may affect the tumour discovery rate.

Evaluation of Gastric Cancer Risk Using Topography of Histological Gastritis: A Large-scaled Cross-sectional Study

We evaluated the topography of histological gastritis, which may be risk factors for gastric cancer (GCa). A total of 530 Helicobacter pylori-positive patients underwent diagnostic upper-gastrointestinal endoscopy. Biopsy specimens were obtained from the gastric antrum and body to assess the grade of gastritis. Subjects were divided into four groups by the topography of active gastritis (antrum predominant gastritis, AP; pan-gastritis with or without corpus atrophy, Pan-1 and Pan-2; and corpus predominant gastritis, CP). A higher prevalence of GCa followed the order of Pan 2→CP→Pan 1→AP. The age of patients decreased in the same order. When we set Pan 2 and CP as a high-risk group, the sensitivity and specificity for GCa detection were 77.3 and 54.7%, which were superior to the serum criteria using pepsinogens. These suggest that topography of histologic gastritis is an important marker to identify the high-risk group.

Helicobacter pylori dupA and gastric acid secretion are negatively associated with gastric cancer development

Few reports have described the cancer prevalence of peptic ulcer patients with long-term follow-up studies. We have conducted a long-term retrospective cohort study of Japanese peptic ulcer patients and evaluated the risk factors for the occurrence of gastric cancer (GCa). A total of 136 patients diagnosed with peptic ulcers from 1975 to 1983 were enrolled. These 136 cases [102 males and 34 females; 69 gastric ulcer (GU) and 67 duodenal ulcer (DU) patients at the time of enrollment; mean follow-up period of 14.4 years (range 1-30 years)] after being matched with a tumour registry database in Hiroshima prefecture were surveyed for GCa. We investigated Helicobacter pylori duodenal ulcer promoter gene A (dupA) using paraffin-embedded gastric biopsy specimens in 56 cases. Gastric acid secretion and basal acid output (BAO) in 40 cases, and maximal acid output in 68 cases, had been measured at first diagnosis of peptic ulcers. GCa was detected in 24 patients (17 with GU, 7 with DU) during the follow-up. The prevalence of GCa was significantly higher in GU patients than in DU patients (log-rank test P<0.05). dupA-positive H. pylori was detected not only in DU patients (9/20) but also in GU patients (9/36). Gastric acid output was significantly larger in quantity in patients with dupA-positive H. pylori than in those with dupA-negative H. pylori (P<0.05). The occurrence of GCa was significantly lower in patients with dupA-positive H. pylori and a high BAO level (log-rank test P<0.05). DUs, higher acid output and dupA-positive H. pylori were negatively associated with GCa.

A combination of the Helicobacter pylori stool antigen test and urea breath test is useful for clinical evaluation of eradication therapy: A multicenter study

Background:  Helicobacter pylori stool antigen (HpSA) test is a new tool for evaluating the H. pylori infection. The present study was carried out to investigate the clinical usefulness of the HpSA test in the evaluation of eradication therapy by comparing it with the 13C‐urea breath test (UBT).

Host factors contributing to the discovery of gastric cancer after successful eradication therapy of Helicobacter pylori: Preliminary report

Background and Aim:  Clinical features of patients who develop gastric cancer after successful eradication of Helicobacter pylori are still unclear. We attempted to identify host factors associated with the discovery of gastric cancer, including changes in the background gastric mucosa in patients with atrophic gastritis.

The effect of Helicobacter pylori eradication therapy on gastric ulcer healing after endoscopic mucosal resection.

Background and Aim It remains unclear whether Helicobacter pylori eradication therapy accelerates the healing of acute gastric ulcer after endoscopic mucosal resection (EMR) of gastric tumor. We examined the effect of H. pylori eradication therapy on ulcer healing after EMR. Methods Twenty-six patients who underwent successful H. pylori eradication therapy before EMR were followed prospectively. Patients underwent endoscopic examination 1 or 2 months after EMR, during which the ulcer status and reduction rate were assessed. The effect of H. pylori eradication on the quality of ulcer healing was also evaluated. Six patients in whom eradication therapy failed and 26 patients who underwent EMR without eradication therapy served as control subjects. Results Endoscopically, 18 (75%) of 24 ulcers in the eradication group were at the healing stage 1 month after EMR. The ulcer reduction rates were 85.0±2.6% and 96.9±1.1% at 1 and 2 months after EMR, respectively. Ulcer stage and reduction rate did not differ significantly between the eradication group and control group. However, we frequently observed a better quality of ulcer healing in the eradication group than in the control groups (P<0.01). Conclusion H. pylori eradication therapy does not accelerate ulcer healing after EMR but may improve the quality of ulcer healing of gastric ulcer after EMR.

Helicobacter pylori cagA polymorphism and gastric inflammation: An international comparison between Japanese and Brazilian patients

Abstract Objective. Gastritis induced by Helicobacter pylori can cause the onset of gastric cancer, and H. pylori cytotoxin associated gene A (cagA) is considered to be an important factor for its development. We investigated the relationship between the grades of gastritis and cagA phenotype in Japanese and Brazilian patients. Material and methods. We studied 47 Brazilian and 47 age-, gender-matched Japanese patients. Status of H. pylori infection, the degree of histologic gastritis, and the levels of serum pepsinogen levels were evaluated. DNA was extracted from paraffin-embedded sections and a portion of the cagA gene was amplified using the polymerase chain reaction, followed by direct sequencing of the fragment. We investigated the cagA subtype using a newly developed restriction fragment length polymorphism (RFLP) system. Results. In H. pylori-positive patients, the grades of histological and serological gastritis were more prominent in the Japanese subjects than their Brazilian counterparts, although no difference was detected in the H. pylori-negative subjects. According to cagA phenotype analysis, our RFLP system was helpful for evaluating cagA phenotype, and we found that the prevalence of the East Asia subtype was significantly higher in the Japanese subjects than in the Brazilian. Conclusion. Infection with H. pylori possessing the East Asian cagA gene contributes to the progression of gastritis.