Adherence and Effectiveness of MoviPrepⓇ in Bowel Preparation for Colonoscopy: A Multicenter Study from the Hiroshima GI Endoscopy Research Group.

Objectives: Bowel preparation is burdensome because of long cleansing times and large dose volumes of conventional polyethylene glycol (PEG) lavage solution NiflecⓇ (Nif). MoviPrep (Mov)Ⓡ is a hyperosmolar preparation of PEG, electrolytes, and ascorbic acid; despite the smaller dose volume of 2 L, it can be challenging for many patients. We examined a more effective and acceptable bowel preparation method without compromising cleanliness and effectiveness, combining low-residue diet and laxative (Modified Brown Method) in Mov administered 1 day pre-colonoscopy. Methods: This multicenter, randomized, open-label, parallel-group comparative study, conducted at Hiroshima University Hospital and 7 affiliated hospitals in May 2015-March 2016, evaluated adherence to and effectiveness of Mov in bowel preparation. Participants (n=380) were allocated to receive 1 of 3 pre-colonoscopy regimens: Nif+Modified Brown Method (Group A), Mov+Modified Brown Method (Group B), or Mov+Laxative (Group C). Results: Total intake volume showed no significant difference among the groups. Bowel preparation time was significantly shorter in Group B (112.4±44.8 min, n=118) than in Groups A (131.3±59 min, n=105) and C (122.6±48.1 min, n=115). Sleep disturbance (37%) was significantly higher in Group B than Group A; distension (11%) was significantly lower in Group C than in Groups A and B (p<0.05, respectively). No severe adverse events occurred in any group. Conclusions: Mov+Modified Brown method provided significantly shorter bowel preparation time, with no significant difference in total intake volume among the regimens. Mov+Laxative yielded significantly less distension than the other groups, with bowel preparation equivalent to that of the Nif+Modified Brown method.

Serum Gastrin and Pepsinogen Levels after Administration of Acid Secretion Inhibitors for Ulcers due to Endoscopic Submucosal Dissection in Patients with Early Gastric Cancer.

Acid secretion inhibitors, such as proton pump inhibitors (PPIs) and potassium competitive acid blockers (PCABs), are used to treat ulcers after endoscopic submucosal dissection (ESD) for early gastric cancer. These drugs can influence serum gastrin and pepsinogen (PG) levels; however, their definite effects remain unclear. This open-label, randomized study investigated the effect of acid secretion inhibitors on the serum gastrin and pepsinogen levels. In total, 76 patients were enrolled in the study. They underwent gastric ESD and received a PPI (n = 21) or PCAB (n = 55). Changes in the serum gastrin and PG levels before and 4 weeks after administration were examined. Patient factors associated with the alteration of serum PG or gastrin levels were identified. The median serum levels of gastrin, PGI, and PGII before the administration of the acid secretion inhibitors were 110.5 pg/mL, 36.4 ng/mL, and 8.9 ng/mL, respectively; after administration, the levels increased to 300 pg/mL, 64.7 ng/mL, and 15.8 ng/mL, respectively (P < 0.01). Univariate analysis revealed that PCABs led to a more significant increase in the serum gastrin and PG levels as compared to PPIs. Furthermore, the PG levels were significantly increased in patients with previous Helicobacter pylori infections than in those with current infections. In conclusion, the serum gastrin and PG levels increased after the use of acid secretion inhibitors. This elevation was affected by the type of drug used, whereas the elevation in PGs was affected by the patient's background as well.

Gastric epithelial neoplasm of fundic-gland mucosa lineage: proposal for a new classification in association with gastric adenocarcinoma of fundic-gland type.

BACKGROUND: Gastric adenocarcinoma of fundic-gland type (GA-FG) is a rare variant of gastric neoplasia. However, the etiology, classification, and clinicopathological features of gastric epithelial neoplasm of fundic-gland mucosa lineage (GEN-FGML; generic term of GA-FG related neoplasm) are not fully elucidated. We performed a large, multicenter, retrospective study to establish a new classification and clarify the clinicopathological features of GEN-FGML. METHODS: One hundred GEN-FGML lesions in 94 patients were collected from 35 institutions between 2008 and 2019. We designed a new histopathological classification of GEN-FGML using immunohistochemical analysis and analyzed via clinicopathological, immunohistochemical, and genetic evaluation. RESULTS: GEN-FGML was classified into 3 major types; oxyntic gland adenoma (OGA), GA-FG, and gastric adenocarcinoma of fundic-gland mucosa type (GA-FGM). In addition, GA-FGM was classified into 3 subtypes; Type 1 (organized with exposure type), Type 2 (disorganized with exposure type), and Type 3 (disorganized with non-exposure type). OGA and GA-FG demonstrated low-grade epithelial neoplasm, and GA-FGM should be categorized as an aggressive variant of GEN-FGML that demonstrated high-grade epithelial neoplasm (Type 2 > 1, 3). The frequent presence of GNAS mutation was a characteristic genetic feature of GEN-FGML (7/34, 20.6%; OGA 1/3, 33.3%; GA-FG 3/24, 12.5%; GA-FGM 3/7, 42.9%) in mutation analysis using next-generation sequencing. CONCLUSIONS: We have established a new histopathological classification of GEN-FGML and propose a new lineage of gastric epithelial neoplasm that harbors recurrent GNAS mutation. This classification will be useful to estimate the malignant potential of GEN-FGML and establish an appropriate standard therapeutic approach.

Helicobacter suis infection is associated with nodular gastritis-like appearance of gastric mucosa-associated lymphoid tissue lymphoma.

Most patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma are infected with Helicobacter pylori, and eradication therapy is the first-line treatment for localized disease with H pylori infection. However, there were several reports showing effectiveness of eradication therapy in even H pylori negative cases. Gastric MALT lymphomas are endoscopically classified into three common types: superficial, ulcerative, and elevated types. For the past 20 years, we have encountered 200 cases of localized gastric MALT lymphoma. Among them, only 4 cases (2%) showed similar macroscopic findings to those of nodular gastritis (gastric MALT lymphoma with nodular gastritis-like appearance; M-NGA). Here, we compared clinicopathological characteristics and prevalence of non-H pylori Helicobacter (NHPH) infection between M-NGA and other common types of gastric MALT lymphoma. To examine the prevalence of NHPH infection, DNA was extracted from formalin-fixed paraffin-embedded biopsy tissues from four cases of M-NGA, 20 cases of common endoscopic types of gastric MALT lymphoma, and 10 cases of nodular gastritis. We used a highly sensitive polymerase chain reaction assay to detect the presence of five species of NHPH (Helicobacter suis, H felis, H bizzozeronii, H salomonis, and H heilmannii). H suis infection was detected in 4, 2, and 0 of the 4, 20, and 10 cases of M-NGA, other types of gastric MALT lymphoma, and nodular gastritis, respectively. Other NHPH species were not detected in any cases. Complete response rate by eradication therapy was 4/4 in M-NGA cases. Therefore, nodular gastritis-like MALT lymphoma, which shows a very rare phenotype, is closely associated with NHPH infection, and eradication therapy may be the first-choice treatment.

Serological Evaluation of Gastric Cancer Risk Based on Pepsinogen and Helicobacter pylori Antibody: Relationship to Endoscopic Findings.

BACKGROUNDS AND AIMS: The serological risk-prediction system combined the pepsinogen (PG) test, and anti-Helicobacter pylori antibody is available for evaluation of gastric cancer risk. In this system, chronic atrophic gastritis (CAG) or H. pylori infection is diagnosed. Subjects with H. pylori negative and PG test negative (group A) are supposed to be those who have never been infected with H. pylori and are at extremely low risk for gastric cancer. However, a certain proportion of patients with CAG has been identified as the extremely low-risk group (group A). Here we examined endoscopic atrophy and investigated its relationship with the ABC classification system. METHODS: We examined 540 patients. All patients underwent an endoscopic examination for evaluating corpus atrophy. Fasting sera were collected and serum PGs and anti-H. pylori antibody (Hp-Ab) titer (E-plate Eiken) were evaluated. RESULTS: Of the 540 patients, 306 were classified into group A. However, 136 of them showed signs of endoscopic atrophy (group A with CAG). Group A with CAG frequently comprised the elderly. A new titer cut-off (<3 U/mL) of the Hp-Ab improved the discrimination of group A with CAG by 8%. CONCLUSION: The prevalence of group A with CAG patients is a critical problem, especially in elderly subjects.

Clinical impact of surveillance colonoscopy using magnification without diminutive polyp removal.

BACKGROUND AND AIM: In Western countries, endoscopic removal of all adenomas during colonoscopy is recommended. The present study evaluates the usefulness of magnifying colonoscopy without removal of diminutive (≤5 mm) colorectal polyps. METHODS: Patients with diminutive polyps who were observed for over 5 years using magnification at Hiroshima University Hospital were selected retrospectively. Lesions ≥6 mm in size, depressed lesions, and lesions with type V pit pattern were indications for endoscopic resection. We investigated the characteristics of lesions indicated for endoscopic resection detected on surveillance colonoscopy and the risk factors for the incidence of lesions indicated for endoscopic resection. RESULTS: A total of 706 consecutive patients were enrolled. Sixty-eight lesions indicated for endoscopic resection were detected, averaging 9.0 ± 4.8 mm, and 33 (49%) lesions were located in the right colon. Pathological diagnoses were adenoma, Tis carcinoma, and T1 carcinoma in 58 (85%), eight (12%), and two (3%) lesions, respectively. Five lesions were considered to grow from previously detected diminutive polyps. Relative risks for the incidence of a lesion indicated for endoscopic resection were 1.76 (95% confidence interval [CI], 1.004-3.23) for males compared with females, 3.76 (95% CI, 2.03-7.50) for more than three polyps at initial colonoscopy compared with one polyp, and 2.84 (95% CI, 1.43-5.24) for patients with carcinoma at initial colonoscopy compared with patients with no lesion indicated for endoscopic resection. Nine carcinomas were resected endoscopically. CONCLUSION: Diminutive low-grade adenomas detected by using magnifying colonoscopy may not necessarily require removal.

Diagnosis of Helicobacter pylori-induced gastritis by serum pepsinogen levels.

BACKGROUND AND AIM: Gastric cancer develops due to atrophic gastritis induced by Helicobacter pylori (H. pylori) infection. Serum levels of pepsinogen (PG) are known to be excellent markers for evaluating the degree of atrophic gastritis. We investigated whether chronic gastritis could be diagnosed by evaluating serum PG levels. METHODS: A total of 4483 patients (average age, 49.7 years; 2879 men) were included in this study. Fasting serum samples were collected and anti-H. pylori antibody and PG levels were evaluated. We evaluated the endoscopic atrophy grade or histological extent of gastritis, and calculated the diagnostic capability of this serum marker. RESULTS: A total of 4483 patients, were diagnosed as being positive (4160) or negative (323) for H. pylori-induced gastritis. In patients with H. pylori-induced gastritis, the PG II levels were higher and the PG I/II ratios were lower than among those without H. pylori gastritis. A cut-off values of (i) PG I/II ≤ 5; (ii) PG II ≥ 10 or PG I/II ≤ 5; (iii) PG II ≥ 12 or PG I/II ≤ 4.5 showed high sensitivity and accuracy (over 90%) for diagnosing H. pylori-induced gastritis. Moreover, in a mass screening of healthy subjects, a cut-off value of PG I/II ≤ 4.5 might be better for diagnosing the presence of gastritis because of a sensitivity and specificity > 80%. CONCLUSIONS: The presence of H. pylori-induced gastritis can be evaluated using serum PG levels.

A computer system to be used with laser-based endoscopy for quantitative diagnosis of early gastric cancer.

GOALS: To evaluate the usefulness of a newly devised computer system for use with laser-based endoscopy in differentiating between early gastric cancer, reddened lesions, and surrounding tissue. BACKGROUND: Narrow-band imaging based on laser light illumination has come into recent use. We devised a support vector machine (SVM)-based analysis system to be used with the newly devised endoscopy system to quantitatively identify gastric cancer on images obtained by magnifying endoscopy with blue-laser imaging (BLI). We evaluated the usefulness of the computer system in combination with the new endoscopy system. STUDY: We evaluated the system as applied to 100 consecutive early gastric cancers in 95 patients examined by BLI magnification at Hiroshima University Hospital. We produced a set of images from the 100 early gastric cancers; 40 flat or slightly depressed, small, reddened lesions; and surrounding tissues, and we attempted to identify gastric cancer, reddened lesions, and surrounding tissue quantitatively. RESULTS: The average SVM output value was 0.846 ± 0.220 for cancerous lesions, 0.381 ± 0.349 for reddened lesions, and 0.219 ± 0.277 for surrounding tissue, with the SVM output value for cancerous lesions being significantly greater than that for reddened lesions or surrounding tissue. The average SVM output value for differentiated-type cancer was 0.840 ± 0.207 and for undifferentiated-type cancer was 0.865 ± 0.259. CONCLUSIONS: Although further development is needed, we conclude that our computer-based analysis system used with BLI will identify gastric cancers quantitatively.

Characteristic epithelium with low-grade atypia appears on the surface of gastric cancer after successful Helicobacter pylori eradication therapy.

BACKGROUND: The incidence of gastric cancer after successful Helicobacter pylori eradication has been increasing. We previously reported that epithelium with low-grade atypia (ELA) appeared on the surface of gastric cancer after H. pylori eradication. Here, we investigate the clinical and biological characteristics of such ELA. METHODS: We studied 27 cases of gastric cancer detected after successful H. pylori eradication therapy. We examined the prevalence of ELA among these cases and its significance for endoscopic discovery after H. pylori eradication. We additionally investigated the mucus, p53 and Ki67 expressions in ELA. RESULTS: Epithelium with low-grade atypia that continuous with the gastric tumor was detected in 22 of 27 cases (81%), a significantly greater percentage than that for controls (p < 0.01). We found that gastric-type mucin was frequently expressed in this epithelium. Neither p53- nor Ki67-positive cells were found in ELA, irrespective of their expression in tumor tissue. The presence of ELA was positively correlated with the clinical interval between H. pylori eradication and gastric cancer detection. CONCLUSIONS: Epithelium with low-grade atypia on gastric cancer tissue, which may develop from gastric cancer cells, is frequently present after successful eradication therapy. This phenomenon could influence the practice of endoscopic diagnosis of gastric cancers.

Characteristics of metachronous gastric tumors after endoscopic submucosal dissection for gastric intraepithelial neoplasms.

Background. Recently, endoscopic submucosal dissection (ESD) has become a standard treatment method for early gastric cancer and concurrent stomach preservation. However, metachronous recurrences have become a major problem. We evaluated the incidence and clinicopathologic features of and examined the risk factors for metachronous gastric tumors. Methods. A total of 357 patients who underwent ESD for gastric tumors (245 early gastric cancers and 112 adenomas) and were followed up for more than 12 months without recurrence within the first 12 months were enrolled. We investigated the incidence and clinicopathologic features of metachronous tumors after ESD. We also analyzed the potential risk factors for metachronous tumors using the Kaplan-Meier method and Cox's proportional hazards model. Results. The annual incidence of metachronous tumors after ESD was 2.4%. The median period until discovery after initial ESD was 26.0 months, and the median observation period was 52.6 months. Male patients developed metachronous tumors more frequently (P = 0.04), and the hazard ratio of female to male patients was 0.36 (95% confidence interval: 0.11-0.89). Conclusions. Patients with a previous history of gastric tumors have a high risk of subsequent gastric tumor development and male patients should be carefully followed up after ESD for gastric tumor.

Advanced method for evaluation of gastric cancer risk by serum markers: determination of true low-risk subjects for gastric neoplasm.

BACKGROUND: Patients with negative anti-Helicobacter pylori antibody titer and high pepsinogen (PG) level (group A) are regarded as having a low risk for gastric cancer. However, gastric cancer cases are occasionally observed in this group. We aimed to elucidate the clinical features of gastric neoplasm in group A patients and reviewed advanced methods for mass screening. MATERIALS AND METHODS: A total of 271 gastric epithelial neoplasm patients were enrolled. We classified them according to the H. pylori-PG system and determined the number of patients in each group. After excluding true H. pylori-negative cases from group A (group A'), we examined the differences between group A' and group non-A. RESULTS: Group A included 30 (11%) patients, and only three of these were true negative for H. pylori. All patients in group A' (n = 27) exhibited endoscopic atrophy in the gastric corpus. Serologically, these patients showed low gastrin, low PG II and high PG I/II ratio, indicative of post-eradication. Histologically, 24 (89%) of these had little inflammation, and 26 (96%) were negative for H. pylori by immunohistochemistry. No difference was observed in the incidence of metachronous gastric tumors between group A' and group non-A. The discriminant function using gastrin and PGs could distinguish these 27 patients from true H. pylori-negative controls with 85% sensitivity and 84% specificity. CONCLUSIONS: Group A included a certain number of patients with atrophic gastritis who were potentially at risk of gastric neoplasm development. Although evaluation of corpus atrophy is necessary for the identification of these patients, the discriminant function may be useful.

Labeling colorectal NBI zoom-videoendoscope image sequences with MRF and SVM.

In this paper, we propose a sequence labeling method by using SVM posterior probabilities with a Markov Random Field (MRF) model for colorectal Narrow Band Imaging (NBI) zoom-videoendoscope. Classifying each frame of a video sequence by SVM classifiers independently leads to an output sequence which is unstable and hard to understand by endoscopists. To make it more stable and readable, we use an MRF model to label the sequence of posterior probabilities. In addition, we introduce class asymmetry for the NBI images in order to keep and enhance frames where there is a possibility that cancers might have been detected. Experimental results with NBI video sequences demonstrate that the proposed MRF model with class asymmetry performs much better than a model without asymmetry.

Quantitative identification of mucosal gastric cancer under magnifying endoscopy with flexible spectral imaging color enhancement.

BACKGROUND AND AIM: Magnifying endoscopy with flexible spectral imaging color enhancement (FICE) is clinically useful in diagnosing gastric cancer and determining treatment options; however, there is a learning curve. Accurate FICE-based diagnosis requires training and experience. In addition, objectivity is necessary. Thus, a software program that can identify gastric cancer quantitatively was developed. METHODS: A bag-of-features framework with densely sampled scale-invariant feature transform descriptors to magnifying endoscopy images of 46 mucosal gastric cancers was applied. Computer-based findings were compared with histologic findings. The probability of gastric cancer was calculated by means of logistic regression, and sensitivity and specificity of the system were determined. RESULTS: The average probability was 0.78 ± 0.25 for the images of cancer and 0.31 ± 0.25 for the images of noncancer tissue, with a significant difference between the two groups. An optimal cut-off point of 0.59 was determined on the basis of the receiver operating characteristic curves. The computer-aided diagnosis system yielded a detection accuracy of 85.9% (79/92), sensitivity for a diagnosis of cancer of 84.8% (39/46), and specificity of 87.0% (40/46). CONCLUSION: Further development of this system will allow for quantitative evaluation of mucosal gastric cancers on magnifying gastrointestinal endoscopy images obtained with FICE.

[Characteristics of H. pylori-negative gastric cancer].

Helicobacter pylori-negative gastric cancer (HpNGC) is known as a rare disease. We demonstrated its prevalence was less than 1% of all gastric cancers in Japan. Patients with HpNGC were younger, and not as predominantly male. The prevalence of diffuse type histology (especially signet ring cell carcinoma) and superficial depressed appearance was significantly higher than ordinary gastric cancer. A half of HpNGCs expressed intestinal type mucus as well as gastric type. Along with the decrease of Hp infection and widespread of eradication therapy, the incidence of gastric cancer will dramatically decrease in the future.

Gastric cancer development after Helicobacter pylori eradication therapy: a new form of gastric neoplasia.

BACKGROUND AND AIM: Along with the widespread use of eradication for Helicobacter pylori (H. pylori), the incidence of gastric cancer after eradication has also been increasing. There is a need for clarification of the clinical and biological characteristics of these neoplasms. PATIENTS AND METHODS: We studied 27 cases of gastric cancer that developed after eradication (group AE). Out of the 27, we selected 26 with early-stage gastric cancer and compared them with 78 age-matched gastric cancer patients with H. pylori infection (group Pos) and 20 patients without H. pylori (group Neg). The patient with autoimmune gastritis was not included. Clinicopathological features, mucus patterns and Wnt5a expressions were compared among these groups. RESULTS: Among group AE patients, there were more males than females, and the tumor histology was mainly intestinal type, a significant difference from group Neg. In contrast, macroscopically, the tumors were predominantly of the flat-depressed type, a feature similar to that of group Neg but significantly different from that of group Pos. MUC2 and Wnt5a expression was significantly lower in group AE than in group Pos. CONCLUSION: Gastric cancer development after eradication may have a carcinogenic pathway similar to that in cancer with H. pylori infection, though macroscopic/biological features may be modified by eradication therapy.

Serum screening for detection of high-risk group for early-stage diffuse type gastric cancer in Japanese.

BACKGROUND AND AIM: Serum screening systems are beneficial for gastric cancer mass surveys; however, the marker for diffuse type gastric cancer (DGC) is not defined. We attempted to define the high-risk group for DGC by using serum markers of anti-Helicobacter pylori antibody and pepsinogens (PG). METHODS: Forty-two patients in the early stage of DGC and 511 controls were enrolled. Fasting serum samples were collected, and anti-H. pylori antibody and PG were evaluated. The risk for DGC was calculated. RESULTS: The prevalence of DGC was higher in H. pylori-positive patients (odds ratio [OR] = 4.3 in men, 9.6 in women). DGC prevalence was significantly higher in the PG1+ group in women (OR = 10.7); however, it was lower in the PG3+ group in both men and women. Patients with PG II ≥ 30 revealed a significantly higher risk for DGC. By combining factors, higher OR (OR = 12.5 in men, 42.7 in women) were obtained when we defined the risk group as H. pylori-positive, PG-negative, and having PG II ≥ 30. CONCLUSION: The risk group for DGC can be defined by evaluating ordinary serum gastritis markers.

Low prevalence of Helicobacter pylori-negative gastric cancer among Japanese.

BACKGROUND AND AIMS: The true prevalence of Helicobacter pylori-negative gastric cancer (HpNGC) is unknown. We attempt to clarify the prevalence and clinicopathologic features of HpNGC in Japanese. METHODS: Helicobacter pylori infection was detected by antibody titer and microscopic observation. In addition, we confirmed the lack of endoscopic atrophy and histologic gastritis. In these cases, we added urea breath test or rapid urease test to confirm the absence of H. pylori. The mucus phenotype of gastric cancer tissue was also evaluated by immunohistochemistry. RESULTS: We screened 3161 gastric cancer cases from 1996 to 2010, and 21 cases were regarded as H. pylori negative. Clinically, patients with HpNGC were younger than patients with H. pylori-positive gastric cancer (controls), and revealed a lack of male dominancy. Histologically, diffuse type was frequently found. All patients examined were pepsinogen negative. Among HpNGC cases with endoscopic resection, the depressed macroscopic appearance was dominant. The prevalence of HpNGC was calculated as 0.66% (95% confidence interval = 0.41-1.01). The mucus phenotype of HpNGC was similar to that of the controls. CONCLUSION: The prevalence of HpNGC is very low and its pathological characteristics are different from common gastric cancer.

Ecabet sodium induces neuronal nitric oxide synthase-derived nitric oxide synthesis and gastric adaptive relaxation in the human stomach.

BACKGROUND: Gastric adaptive relaxation (GAR) is a major factor of functional dyspepsia (FD). Nitric oxide (NO) could be the key molecule responsible for GAR. We previously reported that the physiological gastric reservoir ability can be evaluated by measuring the cross-sectional area of the proximal stomach by abdominal ultrasonography (US). Ecabet sodium (ES), a gastro-protective antiulcer agent, has been shown to improve symptoms in FD patients. We examined the effects of ES on GAR in humans and on NO synthesis in vitro. METHODS: GAR was measured by US in 14 subjects, 8 of whom had a pressure sensor inserted into their stomach, after treatment with ES, placebo, or no drugs. NO was measured in SH-SY 5Y cells using a fluorescent indicator. Neuronal, endothelial and inducible NO synthase (nNOS, eNOS and iNOS, respectively) expressions were examined in SH-SY 5Y cells by Western blotting. RESULTS: Compared to placebo, ES induced significantly greater dilatation of the proximal stomach after the subjects drank 300-400 ml water (P < 0.05). After ES intake, the intragastric pressure did not change significantly, but it tended to be lower (n = 8; P = 0.15). ES increased NO production and nNOS expression, but not iNOS or eNOS expression, in SH-SY 5Y cells in vitro. Pretreatment with non-selective NO synthase (NOS) inhibitor, but not with iNOS-selective inhibitor, reduced NO production by ES. CONCLUSION: ES may promote GAR in humans through nNOS-related NO; therefore, it may be useful for patients with FD.

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.