Quality control in diagnostic immunohistochemistry: integrated on-slide positive controls.

Standardization in immunohistochemistry is a priority in modern pathology and requires strict quality control. Cost containment has also become fundamental and auditing of all procedures must take into account both these principles. Positive controls must be routinely performed so that their positivity guarantees the appropriateness of the immunohistochemical procedure. The aim of this study is to develop a low cost (utilizing a punch biopsy-PB-tool) procedure to construct positive controls which can be integrated in the patient's tissue slide. Sixteen frequently used control blocks were selected and multiple cylindrical samples were obtained using a 5-mm diameter punch biopsy tool, separately re-embedding them in single blocks. For each diagnostic immunoreaction requiring a positive control, an integrated PB-control section (cut from the appropriate PB-control block) was added to the top right corner of the diagnostic slide before immunostaining. This integrated control technique permitted a saving of 4.75% in total direct lab costs and proved to be technically feasible and reliable. Our proposal is easy to perform and within the reach of all pathology labs, requires easily available tools, its application costs is less than using external paired controls and ensures that a specific control for each slide is always available.

Molecular characterization of an Italian series of sporadic GISTs.

PURPOSE: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract. Most (80 %) contain activating mutations in the KIT receptor tyrosine kinase, roughly 10 % in platelet-derived growth factor receptor-alpha (PDGFRA). In a small subset, BRAF mutations are an alternative molecular pathway. GISTs respond well to imatinib, but low response is seen in patients with wild-type KIT or PDGFRA. Resistance has also been reported as a result of mutations in downstream effectors such as BRAF. METHODS: We provide here a molecular characterization of a series of primary GISTs from Italian patients. Of 121 GIST cases diagnosed between 2000 and 2012, 83 were evaluated by PCR amplification and direct sequencing for mutations in KIT exons 8, 9, 11, 13, and 17, PDGFRA exons 12, 14, and 18, and BRAF exon 15. Eighty-one GISTs also underwent K-RAS testing. RESULTS: Sixty-four GISTs were positive: 55 had mutations in KIT and 9 in PDGFRA; 16 patients were mutation negative. Three samples came from NF1 patients and were KIT- and PDGFRA negative. Overall, we identified six novel mutations in KIT (p.K550_M552delinsL, p.Q556_W557delinsG p.Q556_G575del, p.W557_V559delinsQ p.P573_R588dup, p.G592_K593dup) and one novel mutation in PDGFRA (p.D842_N848delinsVDV), thus contributing to widening the spectrum of known mutations in GIST tumors and confirming the most frequently altered regions underlying GIST development. CONCLUSIONS: Among the 64 KIT- and PDGFRA-positive sporadic patients in our series, no BRAF or KRAS mutations were identified, suggesting that co-occurrence of these mutations is likely to be rare in the northwestern Italian population and not a frequent cause of primary resistance to imatinib in KIT-positive GIST patients.

Helicobacter pylori HP(2-20) induces eosinophil activation and accumulation in superficial gastric mucosa and stimulates VEGF-alpha and TGF-beta release by interacting with formyl-peptide receptors.

Eosinophils participate in the immune response against Helicobacter pylori, but little is known about their role in the gastritis associated to the infection. We recently demonstrated that the Hp(2-20) peptide derived from H. pylori accelerates wound healing of gastric mucosa by interacting with N-formyl peptide receptors (FPRs) expressed on gastric epithelial cells. The aim of the present study was to investigate whether eosinophils play a role in the repair of gastric mucosa tissue during H. pylori infection. Immuno-histochemistry and transmission electron microscopy were used to detect eosinophils in gastric mucosal biopsies. Eosinophil re-distribution occurred in the gastric mucosa of H. pylori-infected patients: their density did not change in the deep mucosal layer, whereas it increased in the superficial lamina propria just below the foveolar epithelium; eosinophils entered the epithelium itself as well as the lumen of foveolae located close to the area harboring bacteria, which in turn were also engulfed by eosinophils. The H. pylori-derived peptide Hp(2-20) stimulated eosinophil migration through the engagement of FPR2 and FPR3, and also induced production of VEGF-A and TGF-beta, two key mediators of tissue remodelling. We also demonstrate that Hp(2-20) in vivo induced eosinophil infiltration in rat gastric mucosa after injury brought about by indomethacin. This study suggests that eosinophil infiltrate could modulate the capacity of gastric mucosa to maintain or recover its integrity thereby shedding light on the role of eosinophils in H. pylori infection.

Comparing laparoscopic antireflux surgery with esomeprazole in the management of patients with chronic gastro-oesophageal reflux disease: a 3-year interim analysis of the LOTUS trial.

BACKGROUND: With the introduction of laparoscopic antireflux surgery (LARS) for gastro-oesophageal reflux disease (GORD) along with the increasing efficacy of modern medical treatment, a direct comparison is warranted. The 3-year interim results of a randomised study comparing both the efficacy and safety of LARS and esomeprazole (ESO) are reported. METHODS: LOTUS is an open, parallel-group multicentre, randomised and controlled trial conducted in dedicated centres in 11 European countries. LARS was completed according to a standardised protocol, comprising a total fundoplication and a crural repair. Medical treatment comprised ESO 20 mg once daily, which could be increased stepwise to 40 mg once daily and then 20 mg twice daily in the case of incomplete GORD control. The primary outcome variable was time to treatment failure (Kaplan-Meier analysis). Treatment failure was defined on the basis of symptomatic relapse requiring treatment beyond that stated in the protocol. RESULTS: 554 patients were randomised, of whom 288 were allocated to LARS and 266 to ESO. The two study arms were well matched. The proportions of patients who remained in remission after 3 years were similar for the two therapies: 90% of surgical patients compared with 93% medically treated for the intention to treat population, p = 0.25 (90% vs 95% per protocol). No major unexpected postoperative complications were experienced and ESO was well tolerated. However, postfundoplication complaints remain a problem after LARS. CONCLUSIONS: Over the first 3 years of this long-term study, both laparoscopic total fundoplication and continuous ESO treatment were similarly effective and well-tolerated therapeutic strategies for providing effective control of GORD.

Gastro-oesophageal reflux symptoms, oesophagitis and Barrett's oesophagus in the general population: the Loiano-Monghidoro study.

OBJECTIVE: Existing endoscopy-based data on gastro-oesophageal reflux disease (GORD) in the general population are scarce. This study aimed to evaluate typical symptoms and complications of GORD, and their associated risk factors, in a representative sample of the Italian population. METHODS: 1533 adults from two Italian villages were approached to undergo symptom assessment using a validated questionnaire and upper gastrointestinal endoscopy. Data were obtained from 1033 individuals (67.4% response rate). RESULTS: The prevalence of reflux symptoms was 44.3%; 23.7% of the population experienced such symptoms on at least 2 days per week (frequent symptoms). The prevalence rates of oesophagitis and Barrett's oesophagus in the population were 11.8% and 1.3%, respectively. Both frequent (relative risk (RR) 2.6; 95% confidence interval (CI) 1.7 to 3.9) and infrequent (RR 1.9; 95% CI 1.2 to 3.0) reflux symptoms were associated with the presence of oesophagitis. No reflux symptoms were reported by 32.8% of individuals with oesophagitis and 46.2% of those with Barrett's oesophagus. Hiatus hernia was associated with frequent reflux symptoms and oesophagitis, and was present in 76.9% of those with Barrett's oesophagus. We found no association between body mass index and reflux symptoms or oesophagitis. CONCLUSIONS: GORD is common in Italy, but the prevalence of Barrett's oesophagus in the community is lower than has been reported in selected populations. Both frequent and infrequent reflux symptoms are associated with an increased risk of oesophagitis. Individuals with oesophagitis and Barrett's oesophagus often have no reflux symptoms.

Cell proliferation of squamous epithelium in gastro-oesophageal reflux disease: correlations with clinical, endoscopic and morphological data.

BACKGROUND: The microscopic assessment of squamous epithelium lesions in gastro-oesophageal reflux disease (GERD) is subjective. The Ki67 nuclear antigen expressed by proliferating cells provides an objective measure of regeneration in the squamous epithelium. AIM: To evaluate Ki67 expression in GERD patients and controls, in comparison with histological lesions, pH-metry and endoscopic data. METHODS: Eighty-seven patients with GERD symptoms and 20 symptom-free controls underwent endoscopy and 24-h pH monitoring. Oesophageal biopsies (4 cm, 2 cm and Z-line) were stained with Ki67/MIB-1 antibodies; the Ki67-positive nuclear area was assessed with an image analysis system and expressed as percentage of the whole epithelial area (Ki67-%). RESULTS: Ki67-% was significantly higher in 32 patients with erosive oesophagitis, 44 endoscopy-negative GERD and 11 patients with functional heartburn than in controls (P = 0.0001). Both controls and patients showed a progressive increase in Ki67-% from 4 cm to the Z-line (P < 0.0001). Ki67-% showed a significant correlation with other conventional histological lesions (P ranged between 0.0151 and <0.0001). CONCLUSIONS: Ki67 evaluation provides quantitative and objective data on squamous epithelium proliferative activity. This marker can be applied in the distinction of endoscopy-negative GERD from healthy controls.

The dynamics of the oesophageal squamous epithelium 'normalisation' process in patients with gastro-oesophageal reflux disease treated with long-term acid suppression or anti-reflux surgery.

BACKGROUND: Proton pump inhibitors and laparoscopic anti-reflux surgery (LARS) offer long-term symptom control to patients with gastro-oesophageal reflux disease (GERD). AIM: To evaluate the process of 'normalisation' of the squamous epithelium morphology of the distal oesophagus on these therapies. METHODS: In the LOTUS trial, 554 patients with chronic GERD were randomised to receive either esomeprazole (20-40 mg daily) or LARS. After 5 years, 372 patients remained in the study (esomeprazole, 192; LARS, 180). Biopsies were taken at the Z-line and 2 cm above, at baseline, 1, 3 and 5 years. A severity score was calculated based on: papillae elongation, basal cell hyperplasia, intercellular space dilatations and eosinophilic infiltration. The epithelial proliferative activity was assessed by Ki-67 immunohistochemistry. RESULTS: A gradual improvement in all variables over 5 years was noted in both groups, at both the Z-line and 2 cm above. The severity score decreased from baseline at each subsequent time point in both groups (P < 0.001, all comparisons), attaining a normal level by 5 years. Corresponding decreases in Ki-67 expression were observed (P < 0.001, all comparisons). No significant differences were found between esomeprazole treatment and LARS. Neither baseline severity score nor Ki-67 expression predicted the risk of treatment failure. CONCLUSIONS: Five years of treatment is generally required before squamous epithelial cell morphology and proliferation are 'normalised' in patients with chronic GERD, despite endoscopic and symptomatic disease control. Control of the acid component of the refluxate seems to play the predominant role in restoring tissue morphology.

Non-antigen-specific CD8(+) T suppressor lymphocytes in diseases characterized by chronic immune responses and inflammation.

Recent studies on regulatory lymphocytes demonstrate that CD8(+) T suppressor (Ts) cells may have great relevance in controlling immune system homeostasis and avoiding development of chronic inflammatory diseases. Among the three subpopulations of CD8(+) Ts cells so far recognized in humans, the type 2 (non-antigen-specific) cell is characterized by the capacity to inhibit both T cell proliferation and cytotoxic T lymphocyte activity through secretion of soluble factors. Previous work has shown the impairment of in vitro generation of type 2 CD8(+) Ts cells from the peripheral blood of relapsed patients with multiple sclerosis, systemic lupus erythematosus, or systemic sclerosis. Here, similar findings are demonstrated for patients with human immunodeficiency virus or chronic hepatitis C virus infection. Furthermore, the presence of type 2 CD8(+) Ts cells infiltrating diseased tissues in patients with autoimmune thyroiditis or cancer is shown. Collectively, these findings suggest that type 2 CD8(+) Ts cells may be involved in the control of pathologic chronic immune responses, contributing in some cases to the pathogenesis of the disease.

Long-term safety of proton pump inhibitor therapy assessed under controlled, randomised clinical trial conditions: data from the SOPRAN and LOTUS studies.

BACKGROUND: Control of chronic gastro-oesophageal reflux disease may be achieved either by anti-reflux surgery (ARS) or by long-term medical therapy with proton pump inhibitors (PPIs). The primary efficacy results of the SOPRAN study, comparing long-term omeprazole use with open ARS, and the LOTUS study, comparing long-term esomeprazole use with laparoscopic ARS, have been reported. A secondary objective of these studies was to address the long-term safety of these respective therapeutic strategies and thereby provide a valid scientific platform for assessing long-term PPI safety. AIM: To assess the safety of long-term PPI therapy with omeprazole and esomeprazole through analyses of data from the randomised SOPRAN and LOTUS studies. METHODS: Safety data were collected from patients during the 12-year period of the SOPRAN study (n = 298) and the 5-year period of the LOTUS study (n = 514). Reported serious adverse events (SAEs) and changes in laboratory variables were analysed. RESULTS: Across both studies, SAEs were reported at a similar frequency in the PPI and ARS treatment groups. Taking the time frames into consideration, the number of fatal SAEs in the two studies was low in both treatment groups. Laboratory results, including routine haematology and tests for liver enzymes, electrolytes, vitamin D, vitamin B12 , folate and homocysteine, showed no clinically relevant changes over time. As expected, gastrin and chromogranin A were elevated in the PPI groups, with the greatest increases observed in the first year. CONCLUSION: No major safety concerns arose during 5-12 years of continuous PPI therapy. (ClinicalTrials.gov: NCT00251927 and NCT00256737).

Na+,K(+)-ATPase of gastric cells. A target of Helicobacter pylori cytotoxic activity.

The present study shows a direct impairing action of a cytotoxin-producing Helicobacter pylori strain on the Na+,K(+)-ATPase (evaluated as K(+)-dependent phosphatase activity) of human gastric epithelial cells in culture. The toxin itself is likely involved in this action which may also account for the cell edema found in vivo in Helicobacter pylori-colonized stomach.

p53 gene mutations and protein nuclear accumulation are early events in intestinal type gastric cancer but late events in diffuse type.

We screened for p53 alterations in 71 early gastric cancers of differing histological types and growth patterns, 18 advanced cancers of diffuse type, 19 dysplastic lesions, and 12 extensive intestinal metaplasia cases. Tumors were investigated for gene mutations (exons 5-8) with PCR-based denaturing gradient gel electrophoresis and sequencing techniques, and for protein accumulation with immunohistochemical methods. Nontumor samples were studied with immunohistochemistry alone. Of the early cancers, intestinal tumors showed a much higher p53 mutation frequency (41%) than did diffuse cancers (4%). When comparing early and advanced tumors of the same type, we observed a similarity in mutation frequency (41 versus about 50%) for intestinal tumors, and a significant increase for diffuse tumors (from 4 to 33%). Immunopositive case distribution between tumor types and stages paralleled that of mutated cases. Immunohistochemical and genetic analysis gave concordant results for all samples with gene mutations. Eighteen of the 65 (28%) nonmutated tumors displayed significant immunoreactivity. Early tumors that massively penetrated the submucosa, i.e., the early tumors for which prognosis is worst, showed the highest frequency both of p53 gene mutation and of nonmutated protein accumulation. Twelve of 19 dysplastic lesions showed significant immunoreactivity, whereas intestinal metaplasias proved unreactive in all but a few cells. Our results yield two implications: that p53 alterations have a crucial and early role in gastric carcinogenesis of intestinal type, likely acting at the transition step between metaplasia and dysplasia; and that the alterations are mainly associated with tumor progression in cancer of diffuse type.

Hyperplastic, dysplastic, and neoplastic enterochromaffin-like-cell proliferations of the gastric mucosa. Classification and histogenesis.

Endocrine cells of the gastric oxyntic mucosa, and especially the enterochromaffin-like (ECL) cells, are the progenitors of gastrin-promoted proliferative lesions whose tumorigenic potential largely depends on the background condition in which they arise. Hypertrophic gastropathy due to the familial multiple endocrine neoplasia (MEN-1)-associated or sporadic Zollinger-Ellison syndrome (ZES), diffuse chronic atrophic gastritis restricted to the corpus-fundus (type A CAG), with or without associated pernicious anemia, and Helicobacter pylori-related multifocal chronic atrophic gastritis are the usual background for such growths. The endocrine cell lesions have been classified as pseudohyperplasia (cell clustering unassociated with cell proliferation), hyperplasia (diffuse, linear, micronodular, adenomatoid), dysplasia (enlarged, adenomatous or fused micronodules, microinfiltration, nodular growth), and neoplasia (intramucosal or invasive carcinoids). The entire spectrum of endocrine cell proliferation, from hyperplasia to dysplasia and neoplasia, has been observed in MEN-ZES and diffuse type A CAG. Both hyperplastic and pseudohyperplastic changes occur with some frequency in the H. pylori-related chronic gastritis associated with ulcer disease or dyspepsia. However, because no progression to dysplastic or neoplastic lesions has thus far been documented in these latter conditions, their role in gastric endocrine cell tumorigenesis appears negligible.

Gastric argyrophil carcinoidosis in patients with Zollinger-Ellison syndrome due to type 1 multiple endocrine neoplasia. A newly recognized association.

We report four cases of gastric argyrophil carcinoidosis arising in the oxyntic mucosa of patients with Zollinger-Ellison syndrome as part of type 1 multiple endocrine neoplasia (MEN) syndrome. Multiple mucosal and submucosal carcinoids were seen in combination with innumerable hyperplastic and dysplastic growths of argyrophil endocrine cells disseminated in the entire acidopeptic mucosa. Histochemical and ultrastructural investigation indicated that the argyrophil enterochromaffin-like (ECL) cell, a type of endocrine cell normally restricted to the oxyntic mucosa and very sensitive to gastrin stimulation, was a major component of the carcinoidosis. Five similar cases were found in the literature. Because argyrophil ECL cell carcinoid or carcinoidosis is unusual in patients who have the Zollinger-Ellison syndrome but do not have MEN, we believe that the genetic trait of the MEN syndrome has an important permissive role in the promotion of gastric carcinoids through the hypergastrinemia inherent to Zollinger-Ellison syndrome.

Intestinal and diffuse gastric cancers arise in a different background of Helicobacter pylori gastritis through different gene involvement.

Investigation of extensively sampled nontumor gastric mucosa from 205 early gastric cancers showed Helicobacter pylori colonization in 85% of cases, including 100% of diffuse and 78% (83% in 97 cases with Swiss rolls) of glandular or mixed cancers. Intestinal metaplasia, including its type III variant, was prominent in the mucosa associated with glandular and mixed (but not diffuse) early cancers. Both glandular (usually called "intestinal") and diffuse-type cancers showed admixtures of intestinal and gastric tumor cell phenotypes. Both p53 gene mutations and p53 protein immunostaining were essentially restricted to glandular or mixed cancers and associated dysplastic lesions. Their appearance in the advanced stage of diffuse cancer was partly due to a change of the histologic pattern from glandular to diffuse during progression of some tumors. Loss of laminin, beta I integrin, or zonula adherens junctions was a common finding in both early and advanced diffuse cancer. It is concluded that two main pathways operate in gastric carcinogenesis, both starting from H. pylori gastritis and both leading to phenotypically variable, often mixed gastric/intestinal tumor growth. However, only one of the two pathways involves intestinal metaplasia, its type III variant, p53 gene alteration, and dysplasia to end in glandular cancer. In the other pathway, diffuse cancer apparently arises directly from hyperplastic, sometimes atypical necks of mostly nonmetaplastic gastric glands, through primary involvement of genes affecting cell-cell and cell-matrix junctional proteins.

The pathology of the gastrointestinal endocrine system.

Among endocrine tumors occurring in the gastrointestinal tract, midgut argentaffin EC cell carcinoids, gastric argyrophil ECL cell carcinoids, duodenal gastrin cell tumors, and rectal trabecular L cell carcinoids (in order of decreasing frequency) are those occurring more frequently. Together, they account for more than 80% of such tumors. Duodenal somatostatin cell tumors, gangliocytic paragangliomas, and differentiated neuroendocrine carcinomas are also well-defined tumor entities. The carcinoid syndrome, either classical, with intermittent flushing, hypotension, and diarrhea, or atypical, with persistent histamine-type red flushing, bronchospasm, and no diarrhea, and Zollinger-Ellison syndrome, with severe peptide ulcer disease, are the only hyperfunctional syndromes consistently found in association with these tumors. The carcinoid syndrome occurs in about 10% of gastrointestinal carcinoids, usually in their advanced, metastatic stage. The Zollinger-Ellison syndrome occurs in association with about 40% of intestinal gastrin cell tumors, including small intramural growths. Tumor prognosis depends on the mode and site of presentation, histology, cell type(s), size, level of invasion, metastases (especially distant metastases), and associated clinical syndrome or background disease. Hormones, trophic factors, inherited genetic traits, somatic mutations, and some chronic inflammatory processes are pathogenetically important in a large proportion of cases.

Complement-mediated binding of immunoglobulins to some endocrine cells of the pancreas and gut.

Unspecific binding of immunoglobulins to gastrin, somatostain and glucagon cells of the gastrointestinal mucosa or pancreas has been found to occur through a nonantigen-antibody mechanism mediated by the C14 fraction of complement. The phenomenon represents an important drawback in hormone immunohistochemistry, which can be overcome by using complement deprived, highly dilute anti-hormone sera.

Prognostic significance of DNA content in large bowel carcinoma: a retrospective flow cytometric study.

Flow cytometric (FCM) determination of DNA content was performed on surgical specimens from 44 patients with previously untreated colonic carcinoma. For each tumor, cell suspensions were prepared from 2-4 40-microns thick sections obtained from formalin-fixed and paraffin embedded tissue samples. Aneuploidy was found in 47.2% of all the tumors and the aneuploid clone had a median DNA index of 1.49 (range: 1.24-1.93). Aneuploidy was found in 26.7% of highly differentiated tumors (WHO histologic classification), in 53.8% of moderately differentiated tumors and in 100% of poorly differentiated tumors (P = 0.04). The 33.3% of stages 1 + 2 (TNM) and the 70.6% of stages 3 + 4 tumors were aneuploid (P = 0.002). Median survival from surgery was 46.4 months for all patients. It was 18.8 months for patients with aneuploid tumors and 85.7 months for those with diploid tumors (P = 0.0002). FCM determination of DNA in colon carcinomas can easily be performed on archival histological material and provides prognostic information.

Proton pump inhibitors, enterochromaffin-like cell growth and Helicobacter pylori gastritis.

In both rodents and humans the development of gastrin-promoted gastric argyrophil enterochromaffin-like cell carcinoids requires the involvement of a genetic factor inherent to multiple endocrine neoplasia syndrome or of type A autoimmune chronic atrophic gastritis. Prolonged severe hypergastrinaemia acting on non-gastritic mucosa, as in Zollinger-Ellison syndrome patients, results in diffuse argyrophil enterochromaffin-like cell hyperplasia but, as a rule, does not produce tumours. Combination of chronic atrophic gastritis (mostly related to Helicobacter pylori infection) with hypergastrinaemia frequently causes linear and micronodular hyperplasia of argyrophil cells, whereas carcinoids are exceptional. No tumours or pre-neoplastic lesions have been observed in patients treated long-term with proton pump inhibitors, apart from rare cases in patients with combined Zollinger-Ellison and multiple endocrine neoplasia syndromes. A moderate increase in the incidence of argyrophil cell clustering, with or without hyperplasia, probably results from the parallel evolution of ulcer-associated Helicobacter gastritis into chronic atrophic gastritis. Eradication of H. pylori with a combination of proton pump inhibitors and antibiotics suppresses gastritis and prevents ulcer recurrence.

A randomized, double-blind trial of the efficacy and safety of 10 or 20 mg rabeprazole compared with 20 mg omeprazole in the maintenance of gastro-oesophageal reflux disease over 5 years.

BACKGROUND: Gastro-oesophageal reflux disease has a chronic course, and often requires long-term treatment. Proton pump inhibitors are the treatment of choice for both acute and maintenance treatment, but little is known from randomized controlled trials of their effects beyond 1 year. AIM: To compare the efficacy and safety of two doses of rabeprazole with 20 mg omeprazole in the maintenance treatment of erosive gastro-oesophageal reflux disease over 5 years. METHODS: Two hundred and forty-three patients who had previously responded to acute treatment for erosive gastro-oesophageal reflux disease were prospectively randomized to receive 5 years of treatment with rabeprazole (10 or 20 mg daily) or omeprazole (20 mg daily). The primary outcome measure was endoscopically confirmed relapse of erosive gastro-oesophageal reflux disease. RESULTS: One hundred and twenty-three patients (51%) completed all 5 years of the study, with similar completion rates in the three groups. Relapses occurred in nine of 78 (11.5%), eight of 82 (9.8%) and 11 of 83 (13.3%) patients in the rabeprazole 20 mg, rabeprazole 10 mg and omeprazole 20 mg groups, respectively. Gastric biopsy showed no evidence of any harmful effects. All treatments were well tolerated. CONCLUSIONS: Rabeprazole 10 mg, rabeprazole 20 mg and omeprazole 20 mg all had similar efficacy in the maintenance treatment of gastro-oesophageal reflux disease. All three were safe and well tolerated during 5 years of treatment.