Statins and aspirin for chemoprevention in Barrett's esophagus: results of a cost-effectiveness analysis

Translating Molecular Biology Discoveries to Develop Targeted Cancer Interception in Barrett's Esophagus

Esophageal adenocarcinoma (EAC) is a rapidly increasing lethal tumor. It commonly arises from a metaplastic segment known as Barrett's esophagus (BE), which delineates the at-risk population. Ample research has elucidated the pathogenesis of BE and its progression from metaplasia to invasive carcinoma; and multiple molecular pathways have been implicated in this process, presenting several points of cancer interception. Here, we explore the mechanisms of action of various agents, including proton pump inhibitors, non-steroidal anti-inflammatory drugs, metformin, and statins, and explain their roles in cancer interception. Data from the recent AspECT trial are discussed to determine how viable a multipronged approach to cancer chemoprevention would be. Further, novel concepts, such as the repurposing of chemotherapeutic drugs like dasatinib and the prevention of post-ablation BE recurrence using itraconazole, are discussed.

Targeting Strategies for Aberrant Lipid Metabolism Reprogramming and the Immune Microenvironment in Esophageal Cancer: A Review

Esophageal cancer is of high importance to occurrence, development, and treatment resistance. As evidenced by recent studies, pathways (e.g., Wnt/β-catenin, AMPK, and Hippo) are critical to the proliferation, differentiation, and self-renewal of esophageal cancer. In addition, the above pathways play a certain role in regulating esophageal cancer and act as potential therapeutic targets. Over the past few years, the function of lipid metabolism in controlling tumor cells and immune cells has aroused extensive attention. It has been reported that there are intricate interactions between lipid metabolism reprogramming between immune and esophageal cancer cells, whereas molecular mechanisms should be studied in depth. Immune cells have been commonly recognized as a vital player in the esophageal cancer microenvironment, having complex crosstalk with cancer cells. It is increasingly evidenced that the function of immune cells in the tumor microenvironment (TME) is significantly correlated with abnormal lipid metabolism. In this review, the latest findings in lipid metabolism reprogramming in TME are summarized, and the above findings are linked to esophageal cancer progression. Aberrant lipid metabolism and associated signaling pathways are likely to serve as a novel strategy to treat esophageal cancer through lipid metabolism reprogramming.

Global burden and epidemiology of Barrett oesophagus and oesophageal cancer

Oesophageal cancer is a global health problem; in 2018 there were more than 572,000 people newly diagnosed with oesophageal cancer worldwide. There are two main histological subtypes of oesophageal cancer, oesophageal adenocarcinoma (EAC) and oesophageal squamous cell carcinoma (ESCC), and there has been a dramatic shift in its epidemiology. While the incidence of EAC and its precursor lesion, Barrett oesophagus, has increased in Western populations over the past four decades, the incidence of ESCC has declined in most parts of the world over the same period. ESCC still accounts for the vast majority of all oesophageal cancer cases diagnosed worldwide each year. Prognosis for patients with oesophageal cancer is strongly related to stage at diagnosis. As most patients are diagnosed with late-stage disease, overall 5-year survival for oesophageal cancer remains <20%. Knowledge of epidemiology and risk factors for oesophageal cancer is essential for public health and clinical decisions about risk stratification, screening and prevention. The goal of this Review is to establish the current epidemiology of oesophageal cancer, with a particular focus on the Western world and the increasing incidence of EAC and Barrett oesophagus.

Visceral Obesity, Metabolic Syndrome, and Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) represents an exemplar of obesity-associated carcinogenesis, with a progressive increase in EAC risk with increased body mass index. In this context, there is increased focus on visceral adipose tissue and associated metabolic dysfunction, including hypertension, diabetes mellitus and hyperlipidemia, or combinations of these in the metabolic syndrome. Visceral obesity (VO) may promote EAC via both directly impacting on gastro-esophageal reflux disease and Barrett's esophagus, as well as via reflux-independent effects, involving adipokines, growth factors, insulin resistance, and the microbiome. In this review these pathways are explored, including the impact of VO on the tumor microenvironment, and on cancer outcomes. The current evidence-based literature regarding the role of dietary, lifestyle, pharmacologic and surgical interventions to modulate the risk of EAC is explored.

Chemoprevention of esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) is a major cause of cancer-related death, particularly in Western populations, and is rapidly rising in Asian populations at this time. Virtually all EACs develop from the precursor lesion Barrett's esophagus (BE), which is the most significant risk factor for EAC. However, the rates of progression from BE to EAC are low and patients with BE are asymptomatic. Thus, any strategy for EAC prevention must carry a low risk of harm in order to be clinically useful. Since current EAC-screening and BE-surveillance methods carry some procedural risk and are burdensome, there is an opportunity for chemoprevention, i.e. medications or dietary factors that may prevent BE from progressing to EAC. A variety of candidate chemoprevention therapies have been assessed to date. Proton-pump inhibitors (PPIs) are the best studied and have modest EAC-chemoprevention efficacy in BE patients, with a recent randomized trial showing that high-dose PPI may be more effective than low-dose PPI. Aspirin and other non-steroidal anti-inflammatory drugs have moderate quality observational and randomized-trial evidence for preventing progression of BE to EAC, but their risks for harm have precluded their routine clinical use. Other therapies (statins, metformin, female sex hormones) generally do not have strong evidence to support their use in EAC chemoprevention. Although progress has been made in this field, there is still a need for more effective and safe chemoprevention therapies for EAC.

Acid suppression medications reduce risk of oesophageal adenocarcinoma in Barrett's oesophagus: a nested case-control study in US male veterans

BACKGROUND

Proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs) may reduce the risk of oesophageal adenocarcinoma (OAC) in Barrett's oesophagus; however, current epidemiologic studies are inconclusive.

AIM

To evaluate the independent effects of PPIs and H2RAs on risk of OAC in patients with Barrett's oesophagus.

METHODS

We conducted a nested case-control study of male veterans diagnosed with Barrett's oesophagus. Cases with incident OAC were matched by incidence density sampling on birth year and Barrett's diagnosis date to controls with Barrett's oesophagus who did not develop OAC. We identified prescription medication usage 1 year prior to Barrett's oesophagus diagnosis to 3 months prior to the OAC diagnosis. Odds ratios (OR) and 95% CI were estimated using conditional logistic regression.

RESULTS

Compared with 798 controls, the 300 cases were less likely to use PPIs (90.0% vs 94.5%, P = 0.01) and H2RAs (19.7% vs 25.7%, P = 0.04). In the multivariable model including the use of statins, H2RAs, aspirin and nonsteroidal anti-inflammatory drugs, PPI use was associated with 41% lower risk of OAC (OR 0.59, 95% CI 0.35-0.99). While risk reduction of OAC was stronger for high-dose PPIs (omeprazole daily dose >40 mg, adjusted OR 0.11, 95% 0.04-0.36), we did not find a dose-response relationship with PPI duration (P trend = 0.45). Likewise, H2RA use was independently associated with 30% lower risk of OAC (OR 0.70, 95% CI 0.50-0.99).

CONCLUSION

Use of PPIs and H2RAs among patients with Barrett's oesophagus are associated with lower risk of OAC. Further clinical trials are needed to confirm this possible chemopreventive effect.

Screening and Surveillance for Barrett's Esophagus: Is It Cost-Effective?

The cost-effectiveness of screening and surveillance for Barrett's esophagus continues to evolve as the incidence of esophageal adenocarcinoma increases, biomarkers enhance the identification of individuals at highest risk for developing cancer, and endoscopic eradication of Barrett's esophagus improves. Screening to detect Barrett's esophagus may be cost-effective in selected high-risk groups based on age, race, sex and other factors such as symptoms of heartburn. Currently, endoscopic eradication therapy for Barrett's esophagus and high-grade dysplasia is a cost-effective intervention, while endoscopic therapy for non-dysplastic Barrett's esophagus is not a cost-effective strategy. As diagnosis of low-grade dysplasia improves, endoscopic eradication therapy may also prove to be a cost-effective intervention.

Adjuvant Statin Therapy for Esophageal Adenocarcinoma: A Cost-Utility Analysis

BACKGROUND

Emerging preclinical evidence indicates statins, medications commonly used in the prevention of cardiovascular disease (CVD), inhibit proliferation, promote apoptosis and limit invasiveness of esophageal adenocarcinoma (EAC). Population-based observational data demonstrate statin treatment after diagnosis of EAC is associated with significant reductions in all-cause and cancer-specific mortality. A feasibility study of adjuvant statin therapy following potentially curative resection for EAC has been completed, with planned progression to a full phase III, randomized controlled trial.

OBJECTIVE

The aim was to estimate the cost-utility of statin therapy following surgical resection for EAC from a UK National Health Service (NHS) perspective.

METHODS

A Markov model was developed to estimate the costs and outcomes [quality-adjusted life years (QALYs)] for hypothetical cohorts of patients with EAC exposed or not exposed to statins following potentially curative surgical resection. Model parameters were based on estimates from published observational and trial data. Costs, utilities and transition probabilities were modeled to reflect clinical practice from a payer's perspective. Probabilistic and one-way sensitivity analyses were performed to account for uncertainty in key parameters.

RESULTS

Overall, a cost saving of £6781 per patient was realized with statin treatment compared to no statins. In probabilistic sensitivity analysis, 99% of all iterations were cost saving and 99% of all iterations were less than £20,000 per QALY gained. These results were robust to changes in the price and effectiveness of statins.

CONCLUSIONS

The cohort exposed to statins had lower costs and better QALY outcomes than the no statin cohort. Assuming a causal improvement in disease outcomes following resection for EAC, statin therapy is very likely to be a cost-saving treatment.

Barrett’s oesophagus: Current controversies

Oesophageal adenocarcinoma is rapidly increasing in Western countries. This tumour frequently presents late in its course with metastatic disease and has a very poor prognosis. Barrett’s oesophagus is an acquired condition whereby the native squamous mucosa of the lower oesophagus is replaced by columnar epithelium following prolonged gastro-oesophageal reflux and is the recognised precursor lesion for oesophageal adenocarcinoma. There are multiple national and society guidelines regarding screening, surveillance and management of Barrett’s oesophagus, however all are limited regarding a clear evidence base for a well-demonstrated benefit and cost-effectiveness of surveillance, and robust risk stratification for patients to best use resources. Currently the accepted risk factors upon which surveillance intervals and interventions are based are Barrett’s segment length and histological interpretation of the systematic biopsies. Further patient risk factors including other demographic features, smoking, gender, obesity, ethnicity, patient age, biomarkers and endoscopic adjuncts remain under consideration and are discussed in full. Recent evidence has been published to support earlier endoscopic intervention by means of ablation of the metaplastic Barrett’s segment when the earliest signs of dysplasia are detected. Further work should concentrate on establishing better risk stratification and primary and secondary preventative strategies to reduce the risk of adenocarcinoma of the oesophagus.

Effectiveness and Cost-Effectiveness of Endoscopic Screening and Surveillance

Guidelines for the screening and surveillance of Barrett's esophagus continue to evolve as the incidence of esophageal adenocarcinoma increases, identification of individuals at highest risk for cancer improves, and management of dysplasia evolves. This article reviews related studies and economic analyses. Advances in diagnosis offer promising strategies to help focus screening efforts on those individuals who are most likely to develop esophageal adenocarcinoma.

Progression of Barrett's esophagus toward esophageal adenocarcinoma: an overview

In Barrett's esophagus, normal squamous epithelium is replaced by a metaplastic columnar epithelium as a consequence of chronic gastroesophageal reflux disease. There is a strong association with esophageal adenocarcinoma. In view of the increasing incidence of esophageal adenocarcinoma in the western world, it is important that more attention be paid to the progression of Barrett's esophagus toward esophageal adenocarcinoma. Recently, several molecular factors have been identified that contribute to the sequence towards adenocarcinoma. This might help identify patients at risk and detect new targets for the prevention and treatment of esophageal adenocarcinoma in the future.

Determination of risk for Barrett's esophagus and esophageal adenocarcinoma

PURPOSE OF REVIEW

The incidence of esophageal adenocarcinoma and its precursor, Barrett's esophagus, have increased greatly over the past 40 years and continue to rise. This report summarizes the most recent data on the risk factors for Barrett's esophagus and esophageal adenocarcinoma.

RECENT FINDINGS

Other factors, highly correlated with increasing trends for obesity, are the dominant driver of the increase in incidence of esophageal adenocarcinoma, interacting with gastroesophageal reflux disease symptoms. Abdominal obesity, independently of gastroesophageal reflux disease symptoms, is associated with increased risk of Barrett's esophagus and this association is likely mediated by high levels of leptin and insulin. Use of aspirin, nonsteroidal anti-inflammatory drugs, statins, and proton pump inhibitors are associated with a reduced risk of Barrett's esophagus as well as lower risk of neoplastic progression in patients with Barrett's esophagus. An increasing number of genetic loci have been associated with risk of Barrett's esophagus and esophageal adenocarcinoma.

SUMMARY

Recent advances in identifying risk factors and reporting of more precise estimates of effect for the main risk factors will positively impact clinical risk stratification efforts for Barrett's esophagus and esophageal adenocarcinoma. Large pooling studies are underway to derive and validate reliable clinical risk models.

Statin use reduces risk of esophageal adenocarcinoma in US veterans with Barrett's esophagus: a nested case-control study

BACKGROUND & AIMS

Statins have been reported to protect against esophageal adenocarcinoma (EAC) in patients with Barrett's esophagus (BE). However, there are few data from adequately powered cohort studies of subjects with BE.

METHODS

We conducted a nested case-control study of a cohort of BE patients identified from national Veteran Affairs (VA) outpatient files, diagnosed with BE from 2004 through 2009. New cases of EAC recorded after BE diagnosis were identified during a follow-up period that ended in 2011 and verified using electronic medical records. We selected patients with BE without EAC (controls) using incidence density sampling; 3 controls were matched to each case based on birth year and date of BE diagnosis. Our analysis included only male patients with at least 1 VA visit per year of follow up. We identified prescriptions for statins and non-statin lipid lowering medications filled after BE diagnosis and up to 90 days before EAC diagnosis for cases and controls (during the corresponding time period); we examined the association between statin use and EAC in conditional logistic regression models.

RESULTS

We compared 311 EAC cases to 856 controls. Cases were less likely to use any statins than controls (40.2% vs 54.0%; P < .01). Significantly lower proportions of cases used statins for 6-18 months (10.0% cases vs 17.1% controls) and >18 months (19.3% vs 24.0%, respectively; P < .01). Simvastatin was the most commonly prescribed statin (accounting for 86.9% of statin use); the defined daily dose of simvastatin was lower in cases than in controls (21-40 mg/day, 9.3% vs 14.5%, respectively; and >40 mg/day, 8.4% vs 12.6%, respectively; P < .01). In multivariate analysis, statin use was inversely associated with development of EAC (adjusted odds ratio [OR], 0.65; 95% confidence interval [CI], 0.47-0.91). This protective association was strongest for patients with advanced-stage EAC: in a stratified analysis, comparison of 189 cases with stage 0-1 EAC to 520 controls produced an adjusted OR of 0.85 (95% CI, 0.54-1.33). Among patients with late-stage EAC (stages 2-4, n = 106) and 291 controls, the adjusted OR was 0.44 (95% CI, 0.25-0.79). We found no association between EAC and non-statin lipid-lowering medications.

CONCLUSIONS

In a case-control study of US veterans, statin use among those with BE appeared to decrease the risk of EAC. This protective effect was strongest against advanced-stage EAC, and increased with statin dose.

Obesity and increased risk of esophageal adenocarcinoma

There has been a substantial increase in the incidence of esophageal adenocarcinoma over the past 40 years. Meta-analyses of large prospective cohorts and population-based case-control studies demonstrate consistent associations between obesity and the development of adenocarcinoma of the esophagus and esophago-gastric junction, with an approximate doubling of risk of esophageal adenocarcinoma among patients who are obese, and an almost five-fold increased risk among those with BMI >40 kg/m². The pathologic precursor, specialized intestinal metaplasia in Barrett's esophagus, is also associated with increased adiposity. Epidemiologic evidence suggests that this cancer risk is not solely due to increased gastro-esophageal reflux, and that adipose tissue itself, in particular visceral adipose, may fuel carcinogenesis through the production of adipokines, cytokines, growth factors, and increased inflammation. The robust epidemiologic evidence linking obesity with esophageal adenocarcinoma makes it an exemplar model for investigating the molecular mechanisms underpinning obesity-associated malignant progression, which are discussed in this review.

Cost-Analyses Studies in Barrett's Esophagus: What Is Their Utility?

Approximately 10% to 15% of the chronic gastroesophageal reflux disease population is at risk for the development of Barrett's esophagus, particularly in the setting of other risk factors, including male gender, Caucasian race, age more than 50, and central obesity. The risk of cancer progression for patients with nondysplastic BE has been estimated to be approximately 0.2% to 0.5% per year. Given these low progression rates and the high cost of endoscopic surveillance, cost-effectiveness analyses in this area are useful to determine appropriate resource allocation.

Cost considerations in implementing a screening and surveillance strategy for Barrett's oesophagus

There is increasing concern over the rising costs of healthcare leading to debate regarding the use of resources to implement preventive strategies. Oesophageal adenocarcinoma and its precursor, Barrett's oesophagus provides an excellent opportunity to highlight this issue since cancer is uncommon even among individuals with documented Barrett's oesophagus. This review provides a brief introduction to economic analysis in healthcare and summarizes published studies of the cost-effectiveness of strategies to reduce mortality from cancer. Current best estimates highlight the cost-effectiveness of endoscopic ablation among patients with Barrett's oesophagus and high-grade dysplasia and the low cost-effectiveness of ablation among patients without dysplasia. The cost-effectiveness of ablation among patients with Barrett's and low-grade dysplasia is poorly defined due to the ambiguity of diagnosing dysplasia, the unknown risk of cancer among patients with low-grade dysplasia, and the uncertain durability of ablation to maintain remission from metaplasia and dysplasia and prevent cancer.

The role of inflammation in cancer of the esophagus

Esophageal adenocarcinoma is the eighth most common malignancy worldwide. The overall prognosis is poor, with 5-year survival ranges of approximately 15-25%, and 30-50% for patients who can be treated with curative intent. There has been a marked increase in incidence of esophageal adenocarcinoma over the last 30 years, with chronic and severe reflux, diet and obesity identified as principal factors fuelling this rise in the West. Esophageal adenocarcinoma is an exemplar model of an inflammation-associated cancer. The key molecular pathways driving tumor development and influencing tumor biology are the subject of considerable research efforts, and is the principal focus of this review. In addition, the diverse range of changes occurring in the local immune response, tissue microenvironment, metabolic profile, intracellular signaling mechanisms and microRNA signatures are discussed, as well as novel targeted therapies.

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.