***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: 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 To determine the accuracy of blood tests in predicting normal gastric mucosa confirmed by histological examination of gastric biopsy specimens . METHODS In total , 207 consecutive patients referred for upper endoscopy were included . Two biopsy specimens each from the antrum and corpus were assessed histologically for the presence of Helicobacter pylori , gastritis , and atrophy . Serum sample s were studied for H. pylori antibodies by enzyme immunoassay ( Pyloriset EIA-G and EIA-A ) and by a rapid latex agglutination test ( Pyloriset Dry ) ; pepsinogen I was measured by an immunoenzymometric assay ( Gastroset PGI ) , gastrin by radioimmunoassay , and parietal cell antibodies by indirect immunofluorescence . RESULTS In 101 ( 49 % ) of 207 patients , the gastric mucosa on histologic examination was normal . In the 63 patients aged 45 years or less , H. pylori IgG serology was negative in all 47 patients with normal gastric mucosa and none had low serum pepsinogen I levels . Among 144 patients over age 45 years , 72 had negative H. pylori IgG serology . Combining the serum pepsinogen I assay with the results of H. pylori IgG serology , 12 patients with normal serology but low serum pepsinogen I were found . Thus , 60 patients , 52 of whom showed normal gastric histology , had normal IgG serology and serum pepsinogen 1 . In the remaining eight patients with normal blood tests , the histologic changes were very mild . CONCLUSIONS Although negative H. pylori IgG serology alone in younger patients , and in combination with normal serum pepsinogen I levels in older patients , reliably predicted the presence of normal gastric mucosa , gastroscopy is still recommended for patients over 45 years BACKGROUND AND AIM An algorithm ( GastroPanel ) for the non-invasive diagnosis of atrophic gastritis has been previously proposed , based on serum pepsinogen-I , gastrin-17 , and Helicobacter pylori ( H. pylori ) antibodies . The aim of the present study was to evaluate whether serum markers correlate with and predict gastric atrophy in gastroesophageal reflux disease ( GERD ) patients . METHODS The baseline data of the prospect i ve ProGERD study , a study on the long-term course of GERD ( n=6215 patients ) , served to select patients with atrophic gastritis diagnosed in biopsies from gastric antrum and corpus , and control cases without atrophy . A total of 208 pairs were matched for age , sex , GERD status ( erosive vs non-erosive ) , presence of Barrett 's esophagus , and histological H. pylori status were retrieved .  Serum pepsinogen-I , gastrin-17 , and H. pylori antibodies  were determined using specific enzyme immunoassays . RESULTS A significant negative correlation was found between the degree of corpus atrophy and the level of serum pepsinogen-I. A previously-reported negative correlation between the degree of antral atrophy and serum gastrin-17 could not be confirmed . The low sensitivity ( 0.32 ) and specificity ( 0.70 ) of the GastroPanel algorithm were mainly due to over diagnosis and under diagnosis of advanced atrophy in the antrum . CONCLUSION The diagnostic validity of the GastroPanel algorithm to diagnose gastric atrophy non-invasively is not sufficient for general use in GERD patients AIM Atrophic gastritis ( AG ) , first step in the cascade leading to gastric adenocarcinoma , is related to Helicobacter pylori ( H. pylori ) infection . Currently , the gold st and ard for the diagnosis of AG is esophagogastroduodenoscopy ( EGD ) with histological examination of the biopsy specimens . However , since the latter are taken in r and om order and the distribution of AG is often patchy , histology is only representative of mucosal status . Considering this limitation , a test named GastroPanel ® , that measures the blood concentrations of pepsinogen I and II , gastrin-17 and H. pylori antibodies , has been developed as a potential non-invasive biopsy . Aim of this study has been to assess the accuracy of GastroPanel ® in patients with AG . METHODS Forty-seven dyspeptic patients ( 24 males , mean age 52.2±9.3 years ) , in follow-up for antral or diffuse AG , were enrolled . All underwent at least two EGDs with r and om biopsies and blood collection for GastroPanel ® parameters examination . RESULTS Of the 47 patients , 16 ( 34.1 % ) had histological diagnosis of antral and 31 ( 65.9 % ) multifocal AG ; 17 ( 36.2 % ) patients had mild and 30 ( 63.8 % ) had moderate-severe AG . H. pylori was detected in 39 ( 82.9 % ) and intestinal metaplasia was found in all patients . GastroPanel ® showed 82.9 % sensitivity for the diagnosis of AG and 53.8 % for the diagnosis of H. pylori infection . The prediction of advanced atrophy was not sufficiently accurate , neither in patients with antral nor in those with multifocal AG . CONCLUSION GastroPanel ® can be useful for detecting patients  with AG  . However , it does not reflect the severity of atrophy AIM To assess the possibility of non-invasive screening of atrophic chronic gastritis for preventing further development of gastric cancer . METHODS One hundred and seventy-eight consecutive Helicobacter pylori ( H pylori)-positive dyspeptic patients after detection of serum levels of pepsinogen-1 ( PG-1 ) and gastrin-17 ( G-17 ) by enzyme immunoassay were proposed for endoscopy and histology . The serologic and morphologic results were compared with estimating the sensitivity , specificity and prognostic values of the tests . RESULTS There was statistically significant reverse dependence between the grade of stomach mucosal antral or corpus atrophy and the proper decreasing of serum G17 or PG1 levels . The serologic method was quite sensitive in the diagnosis of non-atrophic and severe antral and corpus gastritis . Also , it was characterized by the high positive and negative prognostic values . CONCLUSION Detection of  serum G-17 and PG1 levels  can be offered as the screening tool for atrophic gastritis . The positive serologic results require further chromoendoscopy with mucosal biopsy , for revealing probable progressing of atrophic process with development of intestinal metaplasia , dysplasia or gastric cancer Aim To estimate the adherence of Western individuals to serum pepsinogen ( PG ) test and its accuracy in the detection of gastric cancer followed by  upper gastrointestinal endoscopy .  Methods Individuals from the northern region of Portugal , aged between 40 and 79 years , were invited to participate in a blood collection for the determination of  serum PG values  by ELISA method ( Biohit kits ) . Participants were classified into two groups : positive ( PG I ⩽70 ng/ml and PG I/ PGII ⩽3 ) and negative ( all others ) . All participants with a positive test and a consecutive r and om sample of participants with a negative test were subjected to endoscopy with biopsy . All the participants ( positive or negative ) subjected to endoscopy were followed up over 5 years . Results From a total of 13 118 participants , 5326 were men ( 41 % ) with a median age of 60 years , and 446 ( 3.4 % ) had a positive test . Of these , 274 ( 61 % ) were subjected to endoscopy . We observed six gastric cancers , five intestinal and one diffuse type , and three early gastric cancers , representing one cancer per approximately 2200 PG tests or one cancer per 74 positive tests . From these 240 participants with a negative test , three patients with gastric cancer were diagnosed during follow-up ( an estimated negative predictive value of 99 % ) . In this study , the PG test showed an estimated sensitivity , specificity , positive predictive value , and negative predictive value of 67 , 47 , 2 , and 99 % , respectively . Conclusion Inhabitants of this high-risk region showed good adherence rate to a gastric cancer detection program based on a PG test followed by upper gastrointestinal endoscopy implemented for the first time . Accuracy estimates were similar to those in Japanese reports , indicating that this methodology could also be used effectively in Western countries with high rates of gastric cancer . Further formal cost-effective studies are however needed BACKGROUND / AIM Russian Federation is among the high-incidence countries for gastric cancer ( GC ) , with the incidence being projected to continue increasing . Using a non-invasive blood test with four stomach-specific biomarkers ( pepsinogen-I ( PG-I ) and -II ( PG-II ) , ami date d gastrin-17 ( G-17 ) and Helicobacter pylori ( HP ) IgG antibodies ) in a hospital-based screening setting , we aim ed to determine the prevalence of GC risk conditions : HP-infection and atrophic gastritis ( AG ) . PATIENTS AND METHODS A population -derived cohort of 918 asymptomatic subjects ( 646 women and 272 men ) with a mean age of 51.8 years ( range=26 - 83 ) was examined with the GastroPanel ® ( GP ) test .  GP results were verified by gastroscopy and biopsies ( the Up date d Sydney System ( USS ) classification for all test-positive AG cases and for r and om 5 % test-negatives ( n=263 ) to correct for the verification bias . RESULTS Of the 918 subjects , only 199 ( 21.7 % ) tested completely normal , while 76.7 % ( 704/918 ) had HP-infection . Altogether , in 99 subjects ( 10.8 % ) , GP suggested AG : atrophic gastritis in the antrum ( AGA ) ( n=21 ) , atrophic gastritis in the corpus 
    Output:
    
Few hypothetical missing studies had only marginal effect on pooled estimates of SE and SP .
This first meta- analysis of GP literature corroborates the statement of international experts , advocating GP in diagnosis and screening of AG .
Due to its high specificity for both AGA and AGC , GastroPanel ® is truly a test for stomach health