Re: Cost-effectiveness of aspirin chemoprevention for Barrett's esophagus

Estimates of benefits and harms of prophylactic use of aspirin in the general population

BACKGROUND

Accumulating evidence supports an effect of aspirin in reducing overall cancer incidence and mortality in the general population. We reviewed current data and assessed the benefits and harms of prophylactic use of aspirin in the general population.

METHODS

The effect of aspirin for site-specific cancer incidence and mortality, cardiovascular events was collated from the most recent systematic reviews. Studies identified through systematic Medline search provided data regarding harmful effects of aspirin and baseline rates of harms like gastrointestinal bleeding and peptic ulcer.

RESULTS

The effects of aspirin on cancer are not apparent until at least 3 years after the start of use, and some benefits are sustained for several years after cessation in long-term users. No differences between low and standard doses of aspirin are observed, but there were no direct comparisons. Higher doses do not appear to confer additional benefit but increase toxicities. Excess bleeding is the most important harm associated with aspirin use, and its risk and fatality rate increases with age. For average-risk individuals aged 50-65 years taking aspirin for 10 years, there would be a relative reduction of between 7% (women) and 9% (men) in the number of cancer, myocardial infarction or stroke events over a 15-year period and an overall 4% relative reduction in all deaths over a 20-year period.

CONCLUSIONS

Prophylactic aspirin use for a minimum of 5 years at doses between 75 and 325 mg/day appears to have favourable benefit-harm profile; longer use is likely to have greater benefits. Further research is needed to determine the optimum dose and duration of use, to identify individuals at increased risk of bleeding, and to test effectiveness of Helicobacter pylori screening-eradication before starting aspirin prophylaxis.

Risk factors for the development of oesophageal adenocarcinoma in Barrett's oesophagus: a UK primary care retrospective nested case-control study

BACKGROUND

Oesophageal adenocarcinoma (OAC) incidence is rising rapidly and prognosis remains poor. Endoscopic surveillance of Barrett's oesophagus (BO) remains controversial.

OBJECTIVE

A nested case-control study was undertaken to evaluate risk factors for progression of BO to OAC, potentially guiding surveillance efforts.

METHODS

The Health Improvement Network database includes general practitioner consultations from 5 million UK subjects. BO subjects with 1-year minimum of follow up were followed until development of OAC or end of time on database. Demographic variables (age, gender, smoking, body mass index) and data on medication considered negatively (aspirin/nonsteroidal anti-inflammatory drugs/proton pump inhibitors) or positively associated (lower oesophageal sphincter-relaxing and asthma drugs) with OAC development were studied. Cox regression analysis-derived hazard ratios with 95% confidence intervals estimated the relative risk for OAC progression.

RESULTS

A total of 3749 BO subjects were studied: 55 developed OAC during 17,743 patient years of follow up, a progression rate of 0.3% per annum. There was 96.7% of the cohort who took proton-pump inhibitors, with no association observed. Increasing age (1.03, 95% CI 1.01-1.05, p = 0.005), male gender (3.06, 95% CI 1.50-6.24, p = 0.002), and having ever smoked (2.36, 95% CI 1.13-4.93, p = 0.023) were associated with progression to OAC, (although smoking lost association on multivariate analysis). Increasing number of drugs used for asthma (2.91, 95% CI 1.10-7.68, p= 0.0314) was also associated.

CONCLUSION

In this nested case-control study of BO, male gender, increasing age, and increasing use of asthma drugs were associated with progression to OAC.

Cost-effectiveness of chemoprevention with proton pump inhibitors in Barrett's esophagus

BACKGROUND

Proton pump inhibitors (PPIs) may reduce the risk of esophageal adenocarcinoma (EAC) in patients with Barrett's esophagus. PPIs are prescribed for virtually all patients with Barrett's esophagus, irrespective of the presence of reflux symptoms, and represent a de facto chemopreventive agent in this population. However, long-term PPI use has been associated with several adverse effects, and the cost-effectiveness of chemoprevention with PPIs has not been evaluated.

AIM

The purpose of this study was to assess the cost-effectiveness of PPIs for the prevention of EAC in Barrett's esophagus without reflux.

METHODS

We designed a state-transition Markov microsimulation model of a hypothetical cohort of 50-year-old white men with Barrett's esophagus. We modeled chemoprevention with PPIs or no chemoprevention, with endoscopic surveillance for all treatment arms. Outcome measures were life-years, quality-adjusted life years (QALYs), incident EAC cases and deaths, costs, and incremental cost-effectiveness ratios.

RESULTS

Assuming 50% reduction in EAC, chemoprevention with PPIs was a cost-effective strategy compared to no chemoprevention. In our model, administration of PPIs cost $23,000 per patient and resulted in a gain of 0.32 QALYs for an incremental cost-effectiveness ratio of $12,000/QALY. In sensitivity analyses, PPIs would be cost-effective at $50,000/QALY if they reduce EAC risk by at least 19%.

CONCLUSIONS

Chemoprevention with PPIs in patients with Barrett's esophagus without reflux is cost-effective if PPIs reduce EAC by a minimum of 19%. The identification of subgroups of Barrett's esophagus patients at increased risk for progression would lead to more cost-effective strategies for the prevention of esophageal adenocarcinoma.

Management strategies of Barrett's esophagus

Barrett’s esophagus is a condition resulting from chronic gastro-esophageal reflux disease with a documented risk of esophageal adenocarcinoma. Current strategies for improved survival in patients with Barrett's adenocarcinoma focus on detection of dysplasia. This can be obtained by screening programs in high-risk cohorts of patients and/or endoscopic biopsy surveillance of patients with known Barrett’s esophagus (BE). Several therapies have been developed in attempts to reverse BE and reduce cancer risk. Aggressive medical management of acid reflux, lifestyle modifications, antireflux surgery, and endoscopic treatments have been recommended for many patients with BE. Whether these interventions are cost-effective or reduce mortality from esophageal cancer remains controversial. Current treatment requires combinations of endoscopic mucosal resection techniques to eliminate visible lesions followed by ablation of residual metaplastic tissue. Esophagectomy is currently indicated in multifocal high-grade neoplasia or mucosal Barrett’s carcinoma which cannot be managed by endoscopic approach.

Aspirin protects against Barrett's esophagus in a multivariate logistic regression analysis

BACKGROUND & AIMS

Better criteria are needed to identify patients who should be screened for Barrett's esophagus (BE) to reduce overtesting and improve the cost effectiveness. There is evidence that chemopreventive agents such as nonsteroidal anti-inflammatory drugs, particularly aspirin, reduce the risk of esophageal adenocarcinoma (EAC), but little is known about their effects on BE. We analyzed characteristics of patients with BE for factors that might be used in screening and management.

METHODS

In this case-controlled study, we identified 434 patients with BE diagnosed at the first endoscopy (incident cases) at a single institution (1997-2010). BE cases were matched with controls on the basis of indication for endoscopy, year of endoscopy, and endoscopist. Risk factors analyzed included age, sex, body mass index, medical and social history, and medications. We performed a multivariate logistic regression analysis to identify clinical risk factors for BE.

RESULTS

In a multivariate regression model, men had a greater risk for developing BE (odds ratio, 3.2; 95% confidence interval, 2.3-4.4), whereas current aspirin users had a lower risk than nonusers (odds ratio, 0.56; 95% confidence interval, 0.39-0.80). A subset analysis, limited to patients who had endoscopies for symptoms of gastroesophageal reflux disease, yielded similar findings. No interactions were found between aspirin use and smoking or use of acid-suppressive medications.

CONCLUSIONS

In a case-controlled study of 434 patients with BE, current aspirin use appeared to reduce the risk of BE; previous studies associated aspirin use with a reduced risk of EAC. Although efforts were made to minimize biases in our analysis, the possibility of residual confounding remains.

Current status and future perspectives on the etiology of esophageal adenocarcinoma

Esophageal adenocarcinoma is the most common type of esophageal cancer in most Western countries and is an important contributor to overall cancer mortality. Most cases of esophageal adenocarcinoma are believed to arise from Barrett’s esophagus. Esophageal adenocarcinoma occurs more frequently in white men over 50 years old, as well as in people with frequent symptoms of gastroesophageal reflux, in smokers and in people who are obese. Higher consumption of fruit and vegetables, use of non-steroidal anti-inflammatory drugs, and infection with Helicobacter pylori have all been shown to reduce the risk of esophageal adenocarcinoma. Here, we review the epidemiological evidence for the major risk factors of esophageal adenocarcinoma and also discuss perspectives for future research.

Chemoprevention of esophageal adenocarcinoma

The incidence of esophageal adenocarcinoma (EAC) is rising rapidly in Western countries, and effective chemoprevention for this malignancy is lacking. Endoscopic surveillance of patients with Barrett's esophagus is currently employed to diagnose EAC at earlier stages, but this strategy has several limitations. Non-steroidal anti-inflammatory drugs and proton pump inhibitors are the most promising agents for prevention of EAC, and a randomized controlled trial of aspirin and esomeprazole is ongoing. Other agents under investigation include green tea, berries, and antioxidants. Cost-effectiveness analyses have shown that chemopreventive agents need to be highly effective at preventing EAC in order to have benefit beyond endoscopic surveillance.

Surveillance of Barrett's oesophagus: do we yet know whether it is worthwhile?

In 2004, the Peninsula Technology Assessment Group developed an economic model to assess the effectiveness and cost effectiveness of surveillance of Barrett's oesophagus in preventing morbidity and mortality from oesophageal adenocarcinoma. The conclusion then was that surveillance was dominated (ie, cost more and conferred less health benefit) by non-surveillance in most scenarios and that surveillance was unlikely to be cost effective at usual levels of willingness to pay. The model outputs were highly sensitive, however, to several parameters for which the data were very uncertain. While there are now better estimates of some of the model inputs, such as cancer risk and quality of life, the revised values make it less likely that surveillance could prove cost effective. There remains considerable uncertainty around other key inputs. At present, there seems little reason to change our original conclusion that surveillance of Barrett's oesophagus is unlikely to be cost effective and a definitive answer may only be possible from clinical trials now in progress. As newer endoscopic techniques for treating Barrett's oesophagus and adenocarcinoma become more widely used, however, conventional surveillance programmes may no longer be undertaken, and revised economic models will be needed to assess the cost effectiveness of the new clinical pathways.

Development, calibration, and validation of a U.S. white male population-based simulation model of esophageal adenocarcinoma

BACKGROUND

The incidence of esophageal adenocarcinoma (EAC) has risen rapidly in the U.S. and western world. The aim of the study was to begin the investigation of this rapid rise by developing, calibrating, and validating a mathematical disease simulation model of EAC using available epidemiologic data.

METHODS

The model represents the natural history of EAC, including the essential biologic health states from normal mucosa to detected cancer. Progression rates between health states were estimated via calibration, which identified distinct parameter sets producing model outputs that fit epidemiologic data; specifically, the prevalence of pre-cancerous lesions and EAC cancer incidence from the published literature and Surveillance, Epidemiology, and End Results (SEER) data. As an illustrative example of a clinical and policy application, the calibrated and validated model retrospectively analyzed the potential benefit of an aspirin chemoprevention program.

RESULTS

Model outcomes approximated calibration targets; results of the model's fit and validation are presented. Approximately 7,000 cases of EAC could have been prevented over a 30-year period if all white males started aspirin chemoprevention at age 40 in 1965.

CONCLUSIONS

The model serves as the foundation for future analyses to determine a cost-effective screening and management strategy to prevent EAC morbidity and mortality.

Early events during neoplastic progression in Barrett's esophagus

Barrett's esophagus is a condition in which the stratified squamous epithelium of the distal esophagus is replaced by specialized intestinal metaplasia. Clinical management of Barrett's esophagus, like many other "premalignant" conditions, is characterized by overdiagnosis of benign early changes that will not cause death or suffering during the lifetime of an individual and underdiagnosis of life-threatening early disease. Recent studies of a number of different types of cancer have revealed much greater genomic complexity than was previously suspected. This genomic complexity could create challenges for early detection and prevention if it develops in premalignant epithelia prior to cancer. Neoplastic progression unfolds in space and time, and Barrett's esophagus provides one of the best models for rapid advances, including "gold standard" cohort studies, to distinguish individuals who do and do not progress to cancer. Specialized intestinal metaplasia has many properties that appear to be protective adaptations to the abnormal environment of gastroesophageal reflux. A large body of evidence accumulated over several decades implicates chromosome instability in neoplastic progression from Barrett's esophagus to esophageal adenocarcinoma. Small, spatial scale studies have been used to infer the temporal order in which genomic abnormalities develop during neoplastic progression in Barrett's esophagus. These spatial studies have provided the basis for prospective cohort studies of biomarkers, including DNA content abnormalities (tetraploidy, aneuploidy) and a biomarker panel of 9p LOH, 17p LOH and DNA content abnormalities. Recent advances in SNP array technology provide a uniform platform to assess chromosome instability.

Aspirin is not chemoprotective for Barrett's adenocarcinoma of the oesophagus in multicentre cohort

Barrett's columnar-lined oesophagus is the precursor lesion for oesophageal adenocarcinoma. The overall rate of progression to adenocarcinoma is 0.59% per annum. A large prospective multicentre trial is recruiting to assess the role of aspirin as a chemoprotective agent in prevention of development of cancer as well as cardiovascular protection in patients with Barrett's oesophagus. This retrospective analysis of the large UK National Barrett's Oesophagus Registry database seeks to analyse this question from within its large natural history study cohort. Multicentre UK retrospective cohort compared patients known to have been taking aspirin with those who did not take aspirin during the course of surveillance for columnar-lined oesophagus. End point was development of dysplasia or oesophageal adenocarcinoma. Analysis was undertaken using Cox's proportional hazard ratio. Total follow-up was 3683 patient-years. Eighty-six patients were taking aspirin, 650 were not taking aspirin (reference group). Numbers of patients developing all grades of dysplasia and adenocarcinoma were: 13 aspirin (15.1%) and 97 no aspirin (14.9%) (hazard ratio 0.723, 95% confidence interval 0.410-1.310, P = 0.294), high-grade dysplasia and adenocarcinoma: five aspirin (5.8%) and 25 no aspirin (3.8%) (hazard ratio 0.898, 95% confidence interval 0.340-2.368, P = 0.827) and adenocarcinoma: four aspirin (4.7%) and 16 no aspirin (2.5%) (hazard ratio 1.092, 95% confidence interval 0.358-3.335, P = 0.877). No significant difference was observed in hazard of developing dysplasia or adenocarcinoma between patients taking aspirin and those not taking aspirin during the course of follow-up of surveillance for columnar-lined oesophagus. In conclusion, no difference in risk of development of dysplasia or adenocarcinoma was observed between patients taking aspirin and those not taking aspirin in this large cohort.

Aspirin and non-steroidal anti-inflammatory drugs for cancer prevention: an international consensus statement

Evidence clearly shows a chemopreventive effect for aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) on colorectal cancer and probably other cancer types; however, data on the risk-benefit profile for cancer prevention are insufficient and no definitive recommendations can be made. Aspirin has emerged as the most likely NSAID for use in chemoprevention because of its known cardiovascular benefit and available safety and efficacy data. Other traditional NSAIDs, particularly sulindac, and selective COX-2 inhibitors are now given to patients at high risk of colorectal cancer, although these drugs do not provide cardioprotection. More studies of aspirin and cancer prevention are needed to define the lowest effective dose, the age at which to initiate therapy, the optimum treatment duration, and the subpopulations for which the benefits of chemoprevention outweigh the risks of adverse side-effects. Although it might be possible to answer some of these questions with longer follow-up of existing clinical trials, randomised controlled trials with new study designs will be needed. Future projects should investigate the effects of aspirin treatment on multiple organ systems. Cancers of interest are colorectal, breast, prostate, lung, stomach, and oesophageal. The main side-effect of aspirin is peptic ulcers; therefore coadministration of aspirin with a proton-pump inhibitor is an attractive option and is under investigation in the AspECT trial.

Aspirin, salicylates, and cancer

Evidence from a wide range of sources suggests that individuals taking aspirin and related non-steroidal anti-inflammatory drugs have reduced risk of large bowel cancer. Work in animals supports cancer reduction with aspirin, but no long-term randomised clinical trials exist in human beings, and randomisation would be ethically unacceptable because vascular protection would have to be denied to a proportion of the participants. However, opportunistic trials of aspirin, designed to test vascular protection, provide some evidence of a reduction in cancer, but only after at least 10 years. We summarise evidence for the potential benefit of aspirin and natural salicylates in cancer prevention. Possible mechanisms of action and directions for further work are discussed, and implications for clinical practice are considered.

Environmental causes of esophageal cancer

This article reviews the environmental risk factors and predisposing conditions for the two main histologic types of esophageal cancer. Tobacco smoking, excessive alcohol consumption, drinking maté, low intake of fresh fruits and vegetables, achalasia, and low socioeconomic status increase the risk of esophageal squamous cell carcinoma. Results of investigations on other potential risk factors, including opium consumption, intake of hot drinks, eating pickled vegetables, poor oral health, and exposure to human papillomavirus, polycyclic aromatic hydrocarbons, N-nitroso compounds, acetaldehyde, and fumonisins are discussed. Gastroesophageal reflux, obesity, tobacco smoking, hiatal hernia, achalasia, and, probably, absence of H pylori in the stomach increase the risk of esophageal adenocarcinoma. Results of studies investigating other factors are also discussed.

Non-steroidal anti-inflammatory drugs and risk of gastric and oesophageal adenocarcinomas: results from a cohort study and a meta-analysis

Use of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) may reduce the risk of gastric or oesophageal adenocarcinomas. We examined the association between self-reported use of aspirin or non-aspirin NSAIDs in the earlier 12 months and gastric non-cardia (N=182), gastric cardia (N=178), and oesophageal adenocarcinomas (N=228) in a prospective cohort (N=311 115) followed for 7 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) come from Cox models adjusted for potential confounders. Use of any aspirin (HR, 95% CI: 0.64, 0.47–0.86) or other NSAIDs (0.68, 0.51–0.92) was associated with a significantly lower risk of gastric non-cardia adenocarcinoma. Neither aspirin (0.86, 0.61–1.20) nor other NSAIDs (0.91, 0.67–1.22) had a significant association with gastric cardia cancer. We found no significant association between using aspirin (1.00, 0.73–1.37) or other NSAIDs (0.90, 69–1.17) and oesophageal adenocarcinoma. We also performed a meta-analysis of the association between the use of NSAIDs and risk of gastric and oesophageal adenocarcinoma. In this analysis, aspirin use was inversely associated with both gastric and oesophageal adenocarcinomas, with summary odds ratios (95% CI) for non-cardia, cardia, and oesophageal adenocarcinomas of 0.64 (0.52–0.80), 0.82 (0.65–1.04), and 0.64 (0.52–0.79), respectively. The corresponding numbers for other NSAIDs were 0.68 (0.57–0.81), 0.80 (0.67–0.95), and 0.65 (0.50–0.85), respectively.

Should patients with Barrett's oesophagus be kept under surveillance? The case for

Oesophageal adenocarcinoma is associated with high mortality rates and its incidence is increasing more rapidly than any other gastrointestinal cancer in the Western world. Several factors, including gastro-oesophageal reflux disease, smoking, alcohol and male gender, are associated with oesophageal adenocarcinoma but none can be used to identify accurately those individuals who will develop adenocarcinoma. It is generally accepted that oesophageal adenocarcinoma arises predominantly in Barrett's oesophagus and it is arguable that Barrett's oesophagus is currently the only clinically useful predictor of oesophageal adenocarcinoma. Surveillance - periodic testing to detect adenocarcinoma or its precursor, high grade dysplasia - is widely recommended for patients with Barrett's oesophagus with the aim of reducing mortality from oesophageal adenocarcinoma. The annual incidence of oesophageal adenocarcinoma in patients with Barrett's oesophagus is 0.5%-1.0% although there is marked variation between studies, attributable variously to publication bias, concurrent acid suppression therapy and differences in patient characteristics. There is limited evidence that surveillance reduces the incidence of oesophageal adenocarcinoma or consequent mortality and the cause of death for patients undergoing surveillance is often unrelated to oesophageal disease. There are, nonetheless, observational studies which suggest that surveillance is associated with earlier detection of malignancy and a reduction in mortality; in addition, data from modelling studies suggest that surveillance can be cost-effective. Furthermore, the advent of new, non-surgical treatments (endoscopic mucosal resection, photodynamic therapy, argon plasma coagulation) for high grade dysplasia and early cancer has reduced the risks associated with therapy for disease detected during surveillance. Surveillance programs have high drop out rates and, for patients who continue surveillance, adherence to standard, published protocols is highly variable. The establishment of specialist Barrett's oesophagus surveillance programs, with coordinator support, has considerable potential to improve adherence to current guidelines, pending the acquisition and publication of data from ongoing studies of chemoprophylaxis and surveillance in the management of Barrett's oesophagus. In consequence, although there is a paucity of data providing unequivocal demonstration of benefit, there is no proof that surveillance is ineffective. It is, therefore, appropriate to offer surveillance for Barrett's oesophagus in accordance with locally-applicable published guidelines after a full informed discussion of the risks and benefits of surveillance and therapy; continued participation should be reviewed regularly to accommodate changes in the patient's health and expectations.

Management of Barrett's esophagus in the UK: overtreated and underbiopsied but improved by the introduction of a national randomized trial

OBJECTIVES

To assess the variation in practice of Barrett's esophagus (BE) management in comparison with accepted international guidelines before and after the introduction of a large BE randomized controlled trial (RCT) with protocols including those of tissue sampling.

DESIGN

A validated anonymized questionnaire was sent to 401 senior attending gastroenterologists asking for details of their current management of BE, especially histological sampling. Of the 228 respondents, 57 individuals (each from a different center) were in the first group to enter the ASPirin Esomeprazole (BE) Chemoprevention Trial (AspECT), and we assessed change in practice in these centers.

RESULTS

Ninety percent of specialists did not take adequate biopsies for histological diagnosis. Furthermore, 74% would consider aggressive surgical resection for prevalent cases of high-grade dysplasia in BE as their first-line choice despite the associated perioperative mortality. Ninety-two percent claim their lack of adherence to guidelines is because there is a need for stronger evidence for surveillance and medical interventions. Effect of the AspECT trial: Those clinicians in centers where the AspECT trial has started have improved adherence to ACG guidelines compared with their previous practice (P < 0.05). BE patients now get 18.8% more biopsies compared with previous practice, and 37.7% if the patient is entered into the AspECT trial (P < 0.01).

CONCLUSIONS

This large study indicates both wide variation in practice and poor compliance with guidelines. Because optimal histology is arguably the most important facet of BE management, the improvement in practice in centers taking part in the AspECT trial indicates an additional value of large international RCTs.

Chemoprevention of gastrointestinal cancer

Lags behind prevention of other diseases

Molecular changes in the progression of Barrett's oesophagus

Barrett's oesophagus is a frequent complication of gastro-oesophageal reflux disease predicting oesophageal adenocarcinoma. The majority of Barrett's patients will not develop cancer, so that specific methods of identification of those at risk are required. Recent molecular studies have identified a selection of candidate biomarkers that need validation in prospective studies. They reflect various changes in cell behaviour during neoplastic progression. The ASPECT trial in the UK aims to establish whether chemoprevention with aspirin and a proton pump inhibitor will reduce adenocarcinoma development and mortality in patients with Barrett's oesophagus. It will also validate biomarkers for progression and clinical response and further study disease pathogenesis.

Risk of mortality and cancer incidence in Barrett's esophagus

BACKGROUND

There are very few prospective follow-up studies of Barrett esophagus (BE) cohorts assessing the risk of extraesophageal cancer incidence or mortality. Such studies are necessary in order to understand the overall risks of cancer and death experienced by patients with BE.

METHODS

A cohort of 502 patients with BE were identified at Leeds General Infirmary, England. Mortality and cancer incidence information were provided by the Office for National Statistics. Standardized mortality ratios (SMR) and standardized incidence ratios (SIR) were calculated using indirect standardization.

RESULTS

All-cause mortality was found to be elevated in patients with BE [SMR, 1.21; 95% confidence interval (95% CI), 1.06, 1.37] and remained so after esophageal cancers were excluded (SMR, 1.16; 95% CI, 1.01-1.32). Increased mortality risks were also found for malignant neoplasms of the esophagus (SMR, 7.26; 95% CI, 3.87-12.42) and diseases of the digestive system (SMR, 2.03; 95% CI, 1.11-3.40). The remaining disease categories produced no altered risk estimates. Circulatory disease mortality was borderline statistically significant (SMR, 1.24; 95% CI, 1.00-1.52; P = 0.053) for those with a specialized intestinal metaplasia diagnosis of BE. In the cancer incidence analyses, esophageal malignancies (SIR, 8.66; 95% CI, 4.73-14.53) and esophageal adenocarcinomas (SIR, 14.29; 95% CI, 7.13-22.56) were found to be increased in BE. All remaining analyses provided unaltered risks, including that of colorectal cancer.

CONCLUSIONS

This study has shown evidence of an increased risk of esophageal cancer incidence and mortality in BE. It has also shown that those who have a histologic BE diagnosis may also have an increased risk of circulatory disease mortality.

The evidence base of proton pump inhibitor chemopreventative agents in Barrett's esophagus--the good, the bad, and the flawed!

Gastric acid is believed to be an important etiological factor in the pathogenesis of Barrett's esophagus. Pulsatile acid exposure increases cell proliferation in ex vivo Barrrett's tissue and normalization of esophageal pH reverses this. Proton pump inhibitors (PPIs) are the mainstay of therapy in Barrett's esophagus, and have numerous beneficial effects including symptom control, reduction of inflammation, and promotion of the development of squamous islands. However, PPI therapy causes hypergastrinemia and has not prevented recent increase in the incidences of esophageal cancer. Additionally, evidence presented here by Feagins et al. suggests that acid exposure has a p53-mediated, antiproliferative effect on a nondysplastic Barrett's epithelial cell line, an effect that acid suppression might abrogate. These complex pH, inflammation, and growth factor biological interactions can be most reliably tested in large clinical trials with hard end points like cancer conversion or all causes of mortality. Combining the anti-inflammatory effects of acid suppression with aspirin, a nonsteroidal anti-inflammatory agent, is the subject of the AspECT clinical trial, and this may be the future of chemoprevention in Barrett's.

Systematic review: Cyclo-oxygenase-2 in human oesophageal adenocarcinogenesis

BACKGROUND

Published in vitro and animal in vivo studies have demonstrated that cyclo-oxygenase-2 plays an important role during oesophageal adenocarcinogenesis. However, the extent to which these studies are directly relevant to events in the human lower oesophagus is questionable.

AIM

To perform a systematic review of all available human studies that have evaluated levels of cyclo-oxygenase-2 expression during the progression from Barrett's metaplasia to oesophageal adenocarcinoma.

METHODS

A literature search was performed to identify all studies which qualitatively or quantitatively assessed cyclo-oxygenase-2 protein or gene expression in either Barrett's, dysplastic or adenocarcinoma tissue in humans.

RESULTS

A total of 27 studies met the inclusion criteria. There was general agreement that cyclo-oxygenase-2 was either absent or very weakly expressed in normal oesophageal squamous mucosa, but considerable disagreement regarding the presence of cyclo-oxygenase-2 in Barrett's and low-grade dysplasia. All studies agreed that high-grade dysplasia and adenocarcinoma expressed cyclo-oxygenase-2 to some extent although levels varied considerably between tissue samples.

CONCLUSIONS

There is conflicting evidence in the literature for cyclo-oxygenase-2 playing an important role in early oesophageal adenocarcinogenesis. Other non-cyclo-oxygenase-2 targets may account for the epidemiological data supporting the use of non-steroidal anti-inflammatory drugs in the chemoprevention of oesophageal adenocarcinoma.

A methodologic analysis of chemoprevention and cancer prevention strategies for gastrointestinal cancer

Gastroenterology lags behind other specialties such as cardiology in the quality of its evidence base for clinical practice. One area where this is particularly evident is in cancer prevention, despite developments in chemoprevention strategies for high-risk patients. For chemoprevention strategies to be successful, we need appropriate clinical networks and translational science infrastructures, model chemoprevention agents and multiple, large, flexible and randomized clinical trials. Translational science must also be embedded into large-scale, long-term, randomized clinical trials that have hard endpoints, so that irrefutable evidence of the longevity of treatment efficacy can be gathered. We also need to be able to identify an individual's cancer risk using valid global patient populations, so that medical benefits can be applied to all, regardless of ethnicity, sex, economic status, age and comorbidities. The future success of gastrointestinal chemoprevention relies on fostering a closer link between basic pharmaceutical research and clinical applications, in a 'bench to bedside and back' manner. In this review we systematically assess the evidence for various cancer prevention strategies, especially chemoprevention, and highlight the obstacles to further exploitation of this knowledge base.

Interactions among smoking, obesity, and symptoms of acid reflux in Barrett's esophagus

BACKGROUND

Barrett's esophagus, a metaplastic precursor to esophageal adenocarcinoma, is becoming increasingly prevalent in many populations. Clinical studies suggest acid reflux causes Barrett's esophagus; however, no population-based estimates of risk have been reported, and the role of other health factors in modifying risk is unclear.

METHODS

We conducted a population-based case-control study in Brisbane, Australia. Cases were 167 patients with histologically confirmed Barrett's esophagus diagnosed between February and December 2003. Age-matched and sex-matched controls (n = 261) were randomly selected from a population register. Data on exposure to self-reported symptoms of acid reflux, smoking, obesity, and other factors were collected through self-completed questionnaires followed by telephone interview. Risks of Barrett's esophagus and Barrett's esophagus with dysplasia associated with these exposures were estimated by the odds ratio (OR) and 95% confidence interval (95% CI), both crude and adjusted for other factors.

RESULTS

Self-reported weekly episodes of acid reflux were associated with greatly increased risks of Barrett's esophagus (adjusted OR, 29.7; 95% CI, 12.2-72.6) and Barrett's esophagus with dysplasia (OR, 59.7; 95% CI, 18.5-193). Smoking was also associated with risk of Barrett's esophagus. We found evidence of interactions between symptoms of acid reflux and smoking and obesity. Obese people with self-reported symptoms of acid reflux had markedly higher risks of Barrett's esophagus (OR, 34.4; 95% CI, 6.3-188) than people with reflux alone (OR, 9.3; 95% CI, 1.4-62.2) or obesity alone (OR, 0.7; 95% CI, 0.2-2.4). Similarly, those reporting both acid reflux symptoms and smoking were at substantially higher risks of Barrett's esophagus (OR, 51.4; 95% CI, 14.1-188) than those reporting acid reflux or smoking alone.

CONCLUSIONS

Although history of symptoms of acid reflux is the principle factor associated with Barrett's esophagus, risks are substantially increased by obesity and smoking.

Non-steroidal anti-inflammatory drugs and risk of neoplastic progression in Barrett's oesophagus: a prospective study

BACKGROUND

Aspirin and other non-steroidal anti-inflammatory drugs (NSAID) probably decrease the risk of colorectal neoplasia; however their effect on development of oesophageal adenocarcinoma is less clear. We aimed to assess the role of NSAID in the development of oesophageal adenocarcinoma and precursor lesions in people with Barrett's oesophagus--a metaplastic disorder that confers a high risk of oesophageal adenocarcinoma.

METHODS

We did a prospective study of the relation between duration, frequency, and recency of NSAID use and the risk of oesophageal adenocarcinoma, aneuploidy, and tetraploidy in a cohort of 350 people with Barrett's oesophagus followed for 20,770 person-months. We used proportional-hazards regression to calculate hazard ratios (HR) adjusted for age, sex, cigarette use, and anthropometric measurements.

FINDINGS

Median follow-up was 65.5 months (range 3.1-106.9). Compared with never users, HR for oesophageal adenocarcinoma (n=37 cases) in current NSAID users was 0.32 (95% CI 0.14-0.76), and in former users was 0.70 (0.31-1.58). 5-year cumulative incidence of oesophageal adenocarcinoma was 14.3% (95% CI 9.3-21.6) for never users, 9.7% (4.5-20.5) for former users, and 6.6% (3.1-13.6) for current NSAID users. When changes in NSAID use during follow up were taken into account, the associations were strengthened: HR for oesophageal adenocarcinoma for current users at baseline or afterwards was 0.20 (95% CI 0.10-0.41) compared with never users. Compared with never users, current NSAID users (at baseline and follow-up) had less aneuploidy (n=35 cases; 0.25 [0.12-0.54]) and tetraploidy (n=45 cases; 0.44 [0.22-0.87]).

INTERPRETATION

NSAID use might be an effective chemopreventive strategy, reducing the risk of neoplastic progression in Barrett's oesophagus.

Review article: management of oesophageal adenocarcinoma -- control of acid, bile and inflammation in intervention strategies for Barrett's oesophagus

Oesophagitis is associated with Barrett's metaplasia in about 10% of individuals. The UK has one of the highest world-wide prevalences of Barrett's metaplasia, with 1% of adults having the condition, resulting in an incidence of oesophageal adenocarcinoma two to three times that seen in either Europe or North America. In addition, the conversion rate to cancer in individuals with Barrett's metaplasia in UK surveillance programmes is twice that observed in the USA (0.96% per year vs. 0.4% per year), lending further support to the notion that the UK is a high-risk region. The evidence base on what can be achieved with medical therapy to reduce the risk of dysplasia or the development of adenocarcinoma needs to be strengthened with data from randomized controlled trials, as existing data have many limitations. Patients with Barrett's metaplasia respond variably to proton pump inhibitor therapy (even high-dose therapy 'normalizes' acid reflux in only 85% of cases), and symptom control is a poor determinant of the adequacy of suppression of acid reflux. Gastro-oesophageal reflux is implicated in the pathogenesis of Barrett's metaplasia, and ex vivo and in vitro evidence suggests that its attenuation reverses proliferation and biological variables over days, and perhaps the metaplastic histology to a degree over years. The effect of proton pump inhibitor therapy on cancer risk in the long term is essentially unknown. Acid suppressant therapy or anti-reflux surgery on its own does not result in the complete regression of the metaplastic epithelium. Bile acids, present especially frequently in the refluxate of Barrett's oesophagus patients, are also likely to influence the development and persistence of metaplasia. Barrett's metaplasia is replaced by a squamous epithelium when acid reflux is well controlled and the epithelium is physically destroyed by ablation with argon plasma coagulation or photodynamic therapy. These modalities are invasive and are not likely to be useful in the routine management of patients with Barrett's oesophagus without dysplasia or cancer. Why metaplasia does not fully regress once external initiating stimuli are removed is a mystery. There is some evidence to implicate a variety of molecules, including cyclo-oxygenase-2, tumour necrosis factor-alpha, beta-catenin nuclear translocation and mitogen-activated protein kinase signalling, because they are expressed preferentially in metaplastic rather than normal or inflamed squamous oesophageal mucosa. The use of non-steroidal anti-inflammatory drugs, including aspirin, is associated with a decreased incidence of oesophageal adenocarcinoma. There is therefore a great need for randomized controlled trials to assess the outcomes of such chemopreventive therapy in patients with Barrett's metaplasia.