***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Helicobacter pylori causes gastric adenocarcinoma ; whether treatment of H. pylori infection prevents this cancer remains unknown . In a r and omized , double-blind , placebo-controlled trial of H. pylori eradication , we determined whether treatment for H. pylori decreases gastric cancer risk , using preneoplastic conditions as surrogate markers . A total of 248 healthy volunteers ( age > 40 years ) r and omly received H. pylori treatment ( omeprazole , amoxicillin , clarythromycin ; n = 122 ) or matched placebo ( n = 126 ) for 1 week . Endoscopy was performed at baseline and at 6 weeks and 1 year . Seven biopsies from each endoscopy were review ed by two pathologists using the revised Sydney classification . Outcome measures were both a consensus “ worst biopsy ” diagnosis and a weighted index score that incorporated degrees of severity of preneoplasia from all biopsies . We compared change in these outcomes over time between the two treatment groups . H. pylori cure rates for compliant subjects in the treatment arm were 79.2 % and 75.7 % at 6 weeks and 1 year , respectively . No statistically significant change in the worst biopsy diagnosis was observed from 6 weeks to 1 year between placebo and treated subjects ( for improvement/worsening , placebo , 19.4%/10.5 % ; treatment , 22.5%/8.3 % ; P = 0.74 ) . Change in index score was favorably greater in treatment compared with placebo subjects ( intention-to-treat analysis , P = 0.03 ) ; this finding was particularly evident in the antrum . H. pylori eradication gave more favorable gastric histopathologies over 1 year than no treatment . Such incomplete regression suggests but does not prove that eradication of H. pylori decreases cancer risk BACKGROUND Conventional endoscopy has low sensitivity , specificity , and interobserver agreement for the diagnosis of gastric atrophy , intestinal metaplasia , and dysplasia .  Magnification chromoendoscopy ( ME ) may optimize the evaluation of premalignant gastric lesions . OBJECTIVE AND DESIGN As part of a multicenter trial , we aim ed at validating a previously proposed classification for gastric methylene blue ME at a different center . SETTING , PATIENTS , AND INTERVENTIONS : A sample of patients ( n = 42 ) with previously diagnosed chronic atrophic gastritis with or without intestinal metaplasia underwent ME ( Pentax EG-3430Z ) with 1 % methylene blue by 2 endoscopists . MAIN OUTCOME MEASUREMENTS A simplified version of a previously published ME classification ( group I , group II [ further divided into subgroups IIE and IIF ] , and group III ) was used for macroscopic  lesions  ( n = 203 ) with Sydney-Houston and Vienna classifications being used for histologic analysis ( n = 479 biopsy specimens ) . RESULTS AND LIMITATIONS Excellent reproducibility ( wK = 0.92 [ 95 % CI , 0.88 - 0.96 ] ) was observed for classification in groups and substantial reproducibility ( wK = 0.78 [ 95 % CI , 0.72 - 0.84 ] ) was found for classification in subgroups . Global validity was 82 % ( range 78%-86 % ) , showing no false negatives ( sensitivity of 100 % [ 1/1 biopsy ] ) and a very low rate of false positives ( specificity 99 % [ 297/299 biopsies ] ) for dysplasia detection . CONCLUSIONS This classification for methylene blue ME was highly reproducible and valid for the diagnosis of premalignant gastric lesions when used in a center different from that involved in its conception . Despite requiring an unconventional endoscope and a longer procedure , these results could reinforce ME as a valuable technique in the surveillance of patients at risk for gastric cancer Background and aims Serum levels of gastrin-17 ( S-G-17 ) and pepsinogen I ( S-PGI ) are biomarkers of gastric antral and corpus mucosa , respectively . In a prospect i ve multicentre investigation , we determined whether these tests , together with the assay of Helicobacter pylori antibodies , are a non-endoscopic tool for the diagnosis of atrophic gastritis . Material s and methods The series comprised 404 consecutive adult out patients undergoing diagnostic upper-gastrointestinal endoscopy for various dyspeptic symptoms in five outpatient clinics .  Gastric biopsies from the antrum and corpus ( at least two biopsies from both sites ) were available from all patients , and they were evaluated according to the guidelines of the up date d Sydney system . S-PGI and S-G-17 were assayed with ELISA methods using monoclonal antibodies to pepsinogen I and ami date d gastrin-17 . In addition to the fasting level ( S-G-17fast ) , a postpr and ial S-G-17 ( S-G-17pr and ) level was measured 20 min after ingestion of a protein-rich drink .  H. pylori antibodies were determined using a polyclonal EIA method . Results S-G-17pr and ( and S-G-17fast ) and S-PGI levels decreased with increasing grade of atrophy of the antrum or corpus , respectively . S-G-17pr and levels were significantly lower in patients with advanced ( moderate or severe ) atrophic antral H. pylori gastritis than in those with non-atrophic H. pylori gastritis . All patients with a resected antrum demonstrated S-G-17pr and levels that were almost undetectable . Of the nine patients with an H. pylori-positive moderate or severe atrophic antral gastritis , six had S-G-17pr and levels below 5 pmol/l . Similarly , S-PGI levels were significantly lower in patients with advanced corpus atrophy than in those without . Of the 45 patients with moderate or severe corpus atrophy in endoscopic biopsies , 35 patients had S-PGI levels < 25 μg/l . By using the cut-off levels for S-G-17pr and and S-PGI with the best discrimination , the sensitivity and specificity of the blood test panel in delineation of patients with advanced atrophic gastritis ( either in the antrum or the corpus , or both ) were 83 % and 95 % , respectively . The predictive values of the positive and negative test results were 75 % and 97 % , respectively . In the diagnosis of atrophic gastritis , the application of S-G-17fast showed a slightly lower sensitivity and specificity than the application of S-G-17pr and as a biomarker for antral atrophy . Conclusions The diagnosis of atrophic gastritis obtained with the blood test panel of S-G-17 , S-PGI and H. pylori antibodies is in good agreement with the endoscopic and biopsy findings . The panel is a tool for non-endoscopic diagnosis and screening of atrophic gastritis Background : Gastric cancer screening using the pepsinogen filter test is receiving wide recognition in Japan owing to convenience , freedom from discomfort or risk , efficiency , and economy . Because the long-term outcomes of cancer development in extensive atrophic gastritis detected by pepsinogen test are unclear , test-positive and test-negative subjects were investigated in a longitudinal cohort study . Methods : Subjects comprised 5,209 middle-aged men with measured serum pepsinogen levels who were followed for 10 years . Cancer development based on “ atrophy-positive ” and “ atrophy-negative ” criteria used for cancer screening was investigated . Results : During the study , 63 cases of cancer developed in the cohort , representing an incidence rate of 125 per 100,000 person-years . Pepsinogen test screening using the most widely used atrophy-positive criterion ( pepsinogen I , ≤70 ng/mL ; pepsinogen I/II ratio , ≤3.0 ) displayed 58.7 % sensitivity , 73.4 % specificity , and 2.6 % positive predictive value . Cancer incidence rate was 276 per 100,000 person-years for the atrophy-positive group and 70 per 100,000 person-years for the atrophy-negative group . Incidence rate was higher in groups fulfilling stricter positive criteria detecting more extensive atrophy , reaching 424 per 100,000 person-years . In addition , 9.2 % of atrophy-negative subjects with pepsinogen I of > 70 ng/mL and pepsinogen I/II ratio of ≤3.0 ( reflecting putative inflammation-based high pepsinogen II level ) are at high risk for cancer , particularly diffuse-type cancer , with a cancer incidence rate comparable with atrophy-positive subjects ( 216 per 100,000 person-years ) . Conclusion : Atrophy-positive subjects by pepsinogen filter test , particularly those fulfilling stricter criteria , and atrophy-negative subjects with low pepsinogen I/II ratio reflecting putative extensive active inflammation constitute population s at high risk for gastric cancer , requiring thorough endoscopic examination . ( Cancer Epidemiol Biomarkers Prev 2008;17(4):838–45 Background : A large proportion of patients attending open access endoscopy  have histological and gross pathological findings that are potentially premalignant . The proportion of these patients who go on to develop malignancies and the timescale over which this occurs are uncertain . Aims : This study aims to discover the incidence of gastric cancers in this “ high risk ” group and to examine the potential for their early diagnosis and treatment . Patients : A total of 1753 patients attended open access endoscopy .  From these , 166 patients with dysplasia , intestinal metaplasia , atrophic gastritis , foveolar hyperplasia , regenerative changes , polyps , or ulcers who agreed to undergo annual surveillance endoscopy  were studied . Methods : Patients were endoscoped annually . Additionally , patients with ulcers were re-examined at two monthly intervals until ulcer healing . Cancers detected were treated by gastrectomy . Results : Twenty two of 1753 patients attending open access endoscopy  had gastric cancer ( 1.3 % ) . In the study population , 14 cancers were detected over 10 years ( 8.4 % ) . These were of an earlier stage than those detected at open access ( stage I and II 67 % v 23 % ; p<0.05 ) and five year survival was significantly higher ( 50 % v 10 % ; p=0.006 ) . In atrophic gastritis and intestinal metaplasia the risk of malignancy was 11 % . Conclusions : In patients with atrophic gastritis or intestinal metaplasia , annual surveillance can detect most new tumours at an early stage with a major improvement in survival . Potential benefits of such a surveillance programme are large and warrant further investigation in a multicentre r and omised controlled trial Objectives Helicobacter pylori infection and atrophic gastritis are related to an increased risk for gastric cancer . There is a decrease in global H. pylori prevalence . We analyzed the prevalence of H. pylori infection in Latvia by the plasma IgG test and the presence of atrophy by means of pepsinogen testing . Methods This sub analysis was carried out on a r and omly selected cross-sectional sample of a general population of adults to access cardiovascular risk factors .  Plasma sample s were screened for H. pylori IgG ( cutoff value 24 U/ml ) , and pepsinogens ( Pg ) I and II . Pg cutoff values of PgI/PgII⩽3 and PgI⩽70 ng/ml were used to assess the prevalence of atrophy of any grade and PgI/PgII⩽2 and PgI⩽30 ng/ml for advanced atrophy . Results Altogether , 3564 serum sample s were available for the study ( 2346 women , 1218 men ; median age 54 years ) . Of the tested individuals , 79.21 % were H. pylori positive , with no difference between sexes . The prevalence increased with age ( P<0.001 ) . Atrophy of any grade was identified in 1444 individuals ( 40.52 % ) and advanced atrophy in 475 individuals ( 13.33 % ) . Linear association with age was present in both response types ( P<0.001 ) . The prevalence of atrophy of any grade was higher in women ( 41.73 % ) than in men ( 38.18 % ; P=0.04 ) ; this difference was lost for advanced atrophy ( women 13.98 % , men 12.07 % ; P=0.1 ) . Conclusion The prevalence of H. pylori infection or atrophy remains high in Latvia . Determining the right cutoff value is critically important for pepsinogen-based atrophy detection in Europe in order to objective ly stratify gastric cancer risk To evaluate an association between Helicobacter pylori ( H. pylori ) infection and chronic atrophic gastritis ( CAG ) , an established precursor of gastric cancer , we performed a cross-sectional study using IgG antibody against H. pylori and pepsinogens of blood donors in four prefectures in Japan . Although a geographic correlation between 
    Output:
    
In countries with a high incidence of gastric cancer , the prevalence of extensive conditions may increase up to 27 % and these patients represent a high-risk population to whom endoscopic surveillance should be offered according to recent guidelines