Barrett's esophagus: proton pump inhibitors and chemoprevention II

Targeting Tumor Microenvironment by Metal Peroxide Nanoparticles in Cancer Therapy

Solid tumors have a unique tumor microenvironment (TME), which includes hypoxia, low acidity, and high hydrogen peroxide and glutathione (GSH) levels, among others. These unique factors, which offer favourable microenvironments and nourishment for tumor development and spread, also serve as a gateway for specific and successful cancer therapies. A good example is metal peroxide structures which have been synthesized and utilized to enhance oxygen supply and they have shown great promise in the alleviation of hypoxia. In a hypoxic environment, certain oxygen-dependent treatments such as photodynamic therapy and radiotherapy fail to respond and therefore modulating the hypoxic tumor microenvironment has been found to enhance the antitumor impact of certain drugs. Under acidic environments, the hydrogen peroxide produced by the reaction of metal peroxides with water not only induces oxidative stress but also produces additional oxygen. This is achieved since hydrogen peroxide acts as a reactive substrate for molecules such as catalyse enzymes, alleviating tumor hypoxia observed in the tumor microenvironment. Metal ions released in the process can also offer distinct bioactivity in their own right. Metal peroxides used in anticancer therapy are a rapidly evolving field, and there is good evidence that they are a good option for regulating the tumor microenvironment in cancer therapy. In this regard, the synthesis and mechanisms behind the successful application of metal peroxides to specifically target the tumor microenvironment are highlighted in this review. Various characteristics of TME such as angiogenesis, inflammation, hypoxia, acidity levels, and metal ion homeostasis are addressed in this regard, together with certain forms of synergistic combination treatments.

Management of Dysplastic Barrett's Esophagus and Early Esophageal Adenocarcinoma

While patients with Barrett's esophagus without dysplasia may benefit from endoscopic surveillance, those with low-grade dysplasia may be managed with either endoscopic surveillance or endoscopic eradication. Patients with Barrett's esophagus with high-grade dysplasia and/or intramucosal adenocarcinoma will generally require endoscopic eradication therapy. The management of Barrett's esophagus with dysplasia and early esophageal adenocarcinoma is predominantly endoscopic, with multiple effective methods available for the resection of raised neoplasia and ablation of flat neoplasia. High-dose proton-pump inhibitor therapy is advised during the treatment of Barrett's esophagus with dysplasia and early esophageal adenocarcinoma. After the endoscopic eradication of Barrett's esophagus and associated neoplasia, surveillance is required for the diagnosis and retreatment of recurrence or progression.

Appropriateness of proton pump inhibitors treatment in clinical practice: Prospective evaluation in outpatients and perspective assessment of drug optimisation

BACKGROUND

High rates of inappropriate proton pump inhibitor (PPI) prescriptions have been reported in retrospective database analyses. Assessing the appropriateness of long-term PPIs in outpatients, with a proactive approach at drug optimisation may enhance treatment adequacy.

AIMS

To describe the characteristics of outpatients who are on long-term PPIs, to assess the magnitude of inappropriate PPI prescriptions, and to evaluate the rate of drug optimisation following specialist recommendations.

METHODS

Appropriateness of long-term (>8weeks) PPI prescription was prospectively assessed in 249 consecutive patients referred to a Gastroenterology outpatient clinic. We recorded reason for prescription, dose, modality, duration of therapy, and attempts at PPI optimisation.

RESULTS

PPIs were inappropriately prescribed in 96/249 patients (38.6%). Gastro-oesophageal reflux disease (50/143, 35.0%) and prophylaxis of anti-platelet/non-steroidal anti-inflammatory drugs (5/49, 10.2%) were the most common PPI indications and those with the lowest rate of inappropriateness, while the highest rates were observed for treatment of dyspepsia (10/12, 83.3%) and anti-coagulant therapy (21/21, 100%). PPI treatment was optimised in 112 patients (45.0%).

CONCLUSIONS

PPIs are inappropriately used in about 40% of outpatients, reflecting scant attention to guidelines. A proactive approach may improve therapeutic adequacy in approximately half of patients. Educational efforts to guide PPI prescription should be further pursued.

Proton Pump Inhibitors and Radiofrequency Ablation for Treatment of Barrett's Esophagus

Gastroesophageal Reflux Disease (GERD) is characterized by acid and bile reflux in the distal oesophagus, and this may cause the development of reflux esophagitis and Barrett's oesophagus (BE). The natural histological course of untreated BE is non-dysplastic or benign BE (ND), then lowgrade (LGD) and High-Grade Dysplastic (HGD) BE, with the expected increase in malignancy transfer to oesophagal adenocarcinoma (EAC). The gold standard for BE diagnostics involves high-resolution white-light endoscopy, followed by uniform endoscopy findings description (Prague classification) with biopsy performance according to Seattle protocol. The medical treatment of GERD and BE includes the use of proton pump inhibitors (PPIs) regarding symptoms control. It is noteworthy that long-term use of PPIs increases gastrin level, which can contribute to transfer from BE to EAC, as a result of its effects on the proliferation of BE epithelium. Endoscopy treatment includes a wide range of resection and ablative techniques, such as radio-frequency ablation (RFA), often concomitantly used in everyday endoscopy practice (multimodal therapy). RFA promotes mucosal necrosis of treated oesophagal region via high-frequency energy. Laparoscopic surgery, partial or total fundoplication, is reserved for PPIs and endoscopy indolent patients or in those with progressive disease. This review aims to explain distinct effects of PPIs and RFA modalities, illuminate certain aspects of molecular mechanisms involved, as well as the effects of their concomitant use regarding the treatment of BE and prevention of its transfer to EAC.

The appropriate use of proton pump inhibitors (PPIs): Need for a reappraisal

The advent of powerful acid-suppressive drugs, such as proton pump inhibitors (PPIs), has revolutionized the management of acid-related diseases and has minimized the role of surgery. The major and universally recognized indications for their use are represented by treatment of gastro-esophageal reflux disease, eradication of Helicobacter pylori infection in combination with antibiotics, therapy of H. pylori-negative peptic ulcers, healing and prophylaxis of non-steroidal anti-inflammatory drug-associated gastric ulcers and control of several acid hypersecretory conditions. However, in the last decade, we have witnessed an almost continuous growth of their use and this phenomenon cannot be only explained by the simple substitution of the previous H2-receptor antagonists, but also by an inappropriate prescription of these drugs. This endless increase of PPI utilization has created an important problem for many regulatory authorities in terms of increased costs and greater potential risk of adverse events. The main reasons for this overuse of PPIs are the prevention of gastro-duodenal ulcers in low-risk patients or the stress ulcer prophylaxis in non-intensive care units, steroid therapy alone, anticoagulant treatment without risk factors for gastro-duodenal injury, the overtreatment of functional dyspepsia and a wrong diagnosis of acid-related disorder. The cost for this inappropriate use of PPIs has become alarming and requires to be controlled. We believe that gastroenterologists together with the scientific societies and the regulatory authorities should plan educational initiatives to guide both primary care physicians and specialists to the correct use of PPIs in their daily clinical practice, according to the worldwide published guidelines.

Barrett’s esophagus in 2016: From pathophysiology to treatment

Esophageal complications caused by gastroesophageal reflux disease (GERD) include reflux esophagitis and Barrett’s esophagus (BE). BE is a premalignant condition with an increased risk of developing esophageal adenocarcinoma (EAC). The carcinogenic sequence may progress through several steps, from normal esophageal mucosa through BE to EAC. A recent advent of functional esophageal testing (particularly multichannel intraluminal impedance and pH monitoring) has helped to improve our knowledge about GERD pathophysiology, including its complications. Those findings (when properly confirmed) might help to predict BE neoplastic progression. Over the last few decades, the incidence of EAC has continued to rise in Western populations. However, only a minority of BE patients develop EAC, opening the debate regarding the cost-effectiveness of current screening/surveillance strategies. Thus, major efforts in clinical and research practice are focused on new methods for optimal risk assessment that can stratify BE patients at low or high risk of developing EAC, which should improve the cost effectiveness of screening/surveillance programs and consequently significantly affect health-care costs. Furthermore, the area of BE therapeutic management is rapidly evolving. Endoscopic eradication therapies have been shown to be effective, and new therapeutic options for BE and EAC have emerged. The aim of the present review article is to highlight the status of screening/surveillance programs and the current progress of BE therapy. Moreover, we discuss the recent introduction of novel esophageal pathophysiological exams that have improved the knowledge of the mechanisms linking GERD to BE.

Ambulatory reflux monitoring in GERD--which test should be performed and should therapy be stopped?

Diagnosing gastroesophageal reflux disease (GERD) often entails using a combination of patient symptoms, response to proton pump inhibitors (PPI), upper endoscopy, and ambulatory reflux testing. Each of these has limitations of which the clinician must be aware when managing patients with reflux symptoms. Ambulatory reflux monitoring, in particular, can potentially document the true presence of pathologic GERD. Consequently, reflux testing is often necessary in our evaluation of patients with reflux symptoms, and can be useful in distinguishing etiologies driving a lack of response to PPI therapy. Reflux testing results can be also used to guide appropriate PPI prescribing and clinical decision making for appropriate or unnecessary therapy. This review focuses on the limitations of our current diagnostic paradigm and highlights how reflux testing can be helpful in the diagnosis and management of patients with poor response to PPI therapy.