Barrett's esophagus: novel strategies for screening and surveillance

Quality indicators in Barrett's endoscopy: Best is yet to come

There is growing interest in establishing quality indicators (QIs) for endoscopic screening and surveillance in Barrett's esophagus (BE). QIs are objective, measurable, and evidence-based metrics that are applicable in a health-care setting to monitor a process and identify key performance indicators (KPIs) to achieve defined goals. In the Barrett's endoscopy setting, QIs can offer a standardized approach to monitor and maintain high-quality endoscopy for BE screening and surveillance that will allow measuring performance of an endoscopist as an individual, a group, or a facility. Since BE is an endoscopically identifiable premalignant condition with histological corroboration, adherence to QIs is paramount for the early and accurate detection of dysplasia and neoplasia. It is the holy grail for BE screening and surveillance. Although several suggested QIs for Barrett's endoscopy exist, issues remain in determining the most appropriate ones. These issues include inconsistent use of terminology, unclear definitions, and a scarcity of studies linking these QIs with relevant patient outcomes, making it difficult for clinicians to understand the concept and clinical importance. Hence, there is an urgent need to determine what should constitute appropriate QIs for Barrett's endoscopy, clearly define items used in the QIs, and identify ways to measure these KPIs. Ultimately, well-defined and validated QIs will contribute to clinically effective, safe, timely, and patient-focused care. In this review, we summarize recent literature and discuss four proposed QIs: (i) neoplasia detection rate; (ii) postendoscopy Barrett's neoplasia; (iii) Barrett's inspection time; and (iv) adherence to the Seattle biopsy protocol.

Endoscopic Management of Esophageal Cancer

Advances in technology and improved understanding of the pathobiology of esophageal cancer have allowed endoscopy to serve a growing role in the management of this disease. Precursor lesions can be detected using enhanced diagnostic modalities and eradicated with ablation therapy. Furthermore, evolution in endoscopic resection has provided larger specimens for improved diagnostic accuracy and offer potential for cure of early esophageal cancer. In patients with advanced esophageal cancer, endoluminal therapy can improve symptom burden and provide therapeutic options for complications such as leaks, perforations, and fistulas. The purpose of this review article is to highlight the role of endoscopy in the diagnosis, treatment, and palliation of esophageal cancer.

Unsedated transnasal endoscopy for the detection of Barrett's esophagus: systematic review and meta-analysis

Conventional esophagogastroduodenoscopy (cEGD) is currently the gold standard endoscopic procedure for diagnosis and surveillance of Barrett's esophagus (BE). This procedure is however less suitable for widespread screening because of its invasiveness and costs. An alternative endoscopic procedure is unsedated transnasal endoscopy (uTNE). We performed a systematic review and meta-analysis to evaluate the diagnostic accuracy, patient tolerability, technical success rate, and safety of uTNE compared with cEGD for detecting BE and related neoplasia. PubMed, EMBASE, and Cochrane Library were searched for studies that reported the diagnostic accuracy of uTNE compared with cEGD for detecting BE and related neoplasia. Eight prospective studies were included, in which 623 patients underwent both uTNE and cEGD. Pooled sensitivity and specificity of uTNE for detecting columnar epithelium were 98% (95% CI 83-100%) and 99% (95% CI 82-100%), respectively. Pooled sensitivity and specificity of uTNE for detecting intestinal metaplasia in biopsies were 89% (95% CI 78-95%) and 93% (95% CI 71-98%), respectively. In three of the six studies that reported patient tolerability, a higher patient tolerability of uTNE compared with cEGD was reported. The technical success rate of uTNE ranged from 89% to 100% and no (serious) adverse events were reported. This systematic review and meta-analysis provides evidence that uTNE is an accurate, safe, and well-tolerated procedure for the detection of columnar epithelium and can be considered as screening modality for BE.

The Use of Confocal Laser Endomicroscopy in Diagnosing Barrett’s Esophagus and Esophageal Adenocarcinoma

Confocal laser endomicroscopy (CLE) is a diagnostic technique that enables real-time microscopic imaging during microscopic examination and evaluation of epithelial structures with 1000-fold magnification. CLE can be used in the diagnosis of various pathologies, in pneumology, and in urology, and it is very widely utilized in gastroenterology, most importantly in the diagnosis of Barrett’s esophagus (BE), esophageal adenocarcinoma (EAC), biliary strictures, and cystic pancreatic lesions. A literature search was made in MEDLINE/PubMed and Google Scholar databases while focusing on diagnostics using CLE of BE and EAC. We then examined randomized and observational studies, systematic reviews, and meta-analyses relating to the utilization of CLE in BE and EAC diagnostics. Here, we discuss whether CLE can be a suitable diagnostic method for surveillance of BE. Even though many studies have proven that CLE increases diagnostic accuracy in detecting neoplastic transformation of BE, CLE is still not used as a standard diagnostic tool in BE surveillance due to a deficiency of scientific evidence. More studies and data are needed if CLE is to find a place as a new technique in BE surveillance.

The evolution of endoscopic therapy for Barrett's esophagus

Barrett’s esophagus is the condition in which a metaplastic columnar epithelium replaces the stratified squamous epithelium that normally lines the distal esophagus. The condition develops as a consequence of chronic gastroesophageal reflux disease and predisposes the patient to the development of esophageal adenocarcinoma. The diagnosis and management of Barrett’s esophagus have undergone dramatic changes over the years and continue to evolve today. Endoscopic eradication therapy has revolutionized the management of dysplastic Barrett’s esophagus and early esophageal adenocarcinoma by significantly reducing the morbidity and mortality associated with the prior gold standard of therapy, esophagectomy. The purpose of this review is to highlight current principles in the management and endoscopic treatment of this disease.

Gastroesophageal reflux disease: recent innovations in endoscopic assessment and treatment

Innovations in endoscopy have brought about some impressive improvements in diagnosing and treating gastroesophageal reflux disease (GERD). GERD, as one of the most prevalent gastrointestinal disorders in the world, has always been on the cutting edge of endoscopic interventions. A primary diagnosis of GERD is based on symptoms and an initial trial of proton-pump inhibitor (PPI) therapy, which is devoid of adequately instructive value for therapeutic strategies. Endoscopy and optional biopsies can be used to directly observe and determine the abnormal structural and pathophysiological damage in the esophagus. The emergence of minimally invasive endoscopic therapy fills the gap between patients who are reluctant or insensitive to PPIs and candidates who are not indicated for surgical anti-reflux fundoplication. In this review, we discuss the utility of endoscopy and biopsy in patients with persistent GERD-related manifestations after proper medical anti-reflux treatment. Moreover, we portray a landscape of four current endoscopic GERD therapies and clarify the merits and disadvantages of each technique. Future research needs to concentrate on stratifying GERD patients based on personal conditions and elucidating the primary pathophysiology of GERD.

Challenges in Determining the Role of Microbiome Evolution in Barrett's Esophagus and Progression to Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) claims the lives of half of patients within the first year of diagnosis, and its incidence has rapidly increased since the 1970s despite extensive research into etiological factors. The changes in the microbiome within the distal esophagus in modern populations may help explain the growth in cases that other common EAC risk factors together cannot fully explain. The precursor to EAC is Barrett's esophagus (BE), a metaplasia adapted to a reflux-mediated microenvironment that can be challenging to diagnose in patients who do not undergo endoscopic screening. Non-invasive procedures to detect microbial communities in saliva, oral swabs and brushings from the distal esophagus allow us to characterize taxonomic differences in bacterial population abundances within patients with BE versus controls, and may provide an alternative means of BE detection. Unique microbial communities have been identified across healthy esophagus, BE, and various stages of progression to EAC, but studies determining dynamic changes in these communities, including migration from proximal stomach and oral cavity niches, and their potential causal role in cancer formation are lacking. Helicobacter pylori is negatively associated with EAC, and the absence of this species has been implicated in the evolution of chromosomal instability, a main driver of EAC, but joint analyses of microbiome and host genomes are needed. Acknowledging technical challenges, future studies on the prediction of microbial dynamics and evolution within BE and the progression to EAC will require larger esophageal microbiome datasets, improved bioinformatics pipelines, and specialized mathematical models for analysis.

Current state of prognostication, therapy and prospective innovations for Barrett's-related esophageal adenocarcinoma: a literature review

Objective

Barrett's esophagus (BE) is the only known precursor to esophageal adenocarcinoma (EAC), which has one of the lowest 5-year survival rates in oncology. The reasons for poor survival are twofold: the large majority of diagnoses are in advanced stages (~80%) and limited treatment options, with a deficit of biology-guided therapies. As a rapidly growing public health concern with poor prognosis, research into the molecular progression for BE and novel therapeutics for EAC currently has high clinical utility. Review of the literature reveals that innovative analysis of metaplastic progression from BE to EAC at a molecular level can shed light on the underlying transformative probabilities of BE into malignant pathologies and may impact current of future therapeutic modalities for management of these diseases.

Background

EAC is the fastest increasing cancer in the United States with a 600% increase over the past 25 years. This cancer arises from dysplastic tissue of BE, a complication of gastroesophageal reflux disease (GERD). Chronic acid and bile reflux in the distal esophagus initiates a metaplastic conversion of normal squamous epithelium to premalignant intestinalized columnar epithelium. Patients with BE have a 125-fold higher risk of cancer compared to the general population.

Methods

We critically reviewed the current status of BE monitoring, and subsequent therapeutic strategies being used in patients who have progressed to cancer. Also, new diagnostic tools and therapeutic candidates for BE-related EAC are discussed. Highly-targeted searches of databases containing recent original peer-reviewed papers were utilized for this review.

Conclusions

Novel and well-described biomarkers analyzed in the patient's diseased tissue will provide for more powerful diagnostics, but also possess the potential to develop strategies for personalized management and identify targets for intervention to either cease disease progression or treat BE and/or EAC. Since millions of Americans develop BE without progressing to cancer, there is a critical need to identify the small percentage of Barrett's patients who possess hallmarks of disease progression or carcinogenesis with novel screening techniques. Incorporation of such tools into standard screening protocols for BE surveillance and/or therapy would be critical to detect malignant transformations before clinically obvious cancer ever develops.

Endoscopic management of Barrett's esophagus: Western perspective of current status and future prospects

Barrett's esophagus (BE) is a precursor to esophageal adenocarcinoma and current practice is to establish endoscopic surveillance once diagnosed, in order to identify early dysplasia and neoplasia that has the potential to undergo endoscopic eradication therapy (EET). Before embarking upon EET the clinical team has a duty to consider all viable options and come to a plan based on recent evidence. The therapeutic approach varies greatly but largely adheres to the mantra of 'Detect-Resect-Ablate', in which high-quality endoscopy identifies BE associated pathology, associated lesions (if present) undergo safe endoscopic resection and remaining intestinal metaplasia in the esophagus is ablated to prevent recurrence of dysplasia. In this review, current practice, pitfalls, complications, and the future perspectives on practice in this field are discussed. The Western perspective is focused on here, with an outline of the differences in clinical practice with Asian nations and attempts to bridge these differences.

WATS3D versus forceps biopsy in screening for Barrett's esophagus: experience in community endoscopy centers

Background

Barrett’s esophagus (BE) is a premalignant condition diagnosed using systematic 4-quadrant forceps biopsies (FB) during endoscopy. This method is fraught with errors due to the randomness of sampling and variability among operators. Wide-area transepithelial sampling with 3-dimensional computer-assisted analysis (WATS^3D) is an emerging technique used to collect esophageal samples. The aim of this study was to evaluate WATS^3D as a diagnostic tool for detecting BE in addition to FB, compared to FB alone.

Methods

A retrospective observational cohort study was conducted and included patients who underwent screening for BE with WATS^3D and FB between January 2015 and January 2019 across 3 endoscopy centers in Wichita, Kansas. The FB specimens were reviewed by community pathologists, while the WATS^3D samples were sent to CDX technology labs, NY.

Results

A total of 108 patients were screened for BE using both modalities concurrently. FB and WATS^3D detected 62 (57.4%) and 83 (76%) cases of BE, respectively. The absolute difference of 21 cases (18.6%) of BE was attributed to the addition of WATS^3D. The number needed to test with WATS^3D was 5. We divided the sample into 4 groups to compare the agreement across all groups: (FB–; WATS^3D+), (FB–; WATS^3D–), (FB+; WATS^3D+), and (FB+ and WATS^3D–). Overall agreement by kappa statistic was 0.74.

Conclusion

WATS^3D identified 21 cases of BE missed by FB. Using WATS^3D in addition to FB increased the yield of BE during surveillance endoscopy, with no increase in complications.

Does the nissen fundoplication procedure improve esophageal dysmotility in patients with barrett's esophagus?

OBJECTIVE

to evaluate esophageal dysmotility (ED) and the extent of Barrett's esophagus (BE) before and after laparoscopic Nissen fundoplication (LNF) in patients previously diagnosed with BE and ED.

METHODS

twenty-two patients with BE diagnosed by upper gastrointestinal (GI) endoscopy with biopsies and ED diagnosed by conventional esophageal manometry (CEM) were submitted to a LNF, and followed up with clinical evaluations, upper GI endoscopy with biopsies and CEM, for a minimum of 12 months after the surgical procedure.

RESULTS

: sixteen patients were male (72.7%) and six were females (27.3%). The mean age was 55.14 (± 15.52) years old. and the mean postoperative follow-up was 26.2 months. The upper GI endoscopy showed that the mean length of BE was 4.09 cm preoperatively and 3.91cm postoperatively (p=0.042). The evaluation of esophageal dysmotility through conventional manometry showed that: the preoperative median of the lower esophageal sphincter resting pressure (LESRP) was 9.15 mmHg and 13.2 mmHg postoperatively (p=0.006). The preoperative median of the esophageal contraction amplitude was 47.85 mmHg, and 57.50 mmHg postoperatively (p=0.408). Preoperative evaluation of esophageal peristalsis showed that 13.6% of the sample presented diffuse esophageal spasm and 9.1% ineffective esophageal motility. In the postoperative, 4.5% of patients had diffuse esophageal spasm, 13.6% of aperistalsis and 22.7% of ineffective motor activity (p=0.133).

CONCLUSION

LNF decreased the BE extension, increased the LES resting pressure, and increased the amplitude of the distal esophageal contraction; however, it was unable to improve ED.

Artificial Intelligence and Its Role in Identifying Esophageal Neoplasia

Randomized trials have demonstrated that ablation of dysplastic Barrett's esophagus can reduce the risk of progression to cancer. Endoscopic resection for early stage esophageal adenocarcinoma and squamous cell carcinoma can significantly reduce postoperative morbidity compared to esophagectomy. Unfortunately, current endoscopic surveillance technologies (e.g., high-definition white light, electronic, and dye-based chromoendoscopy) lack sensitivity at identifying subtle areas of dysplasia and cancer. Random biopsies sample only approximately 5% of the esophageal mucosa at risk, and there is poor agreement among pathologists in identifying low-grade dysplasia. Machine-based deep learning medical image and video assessment technologies have progressed significantly in recent years, enabled in large part by advances in computer processing capabilities. In deep learning, sequential layers allow models to transform input data (e.g., pixels for imaging data) into a composite representation that allows for classification and feature identification. Several publications have attempted to use this technology to help identify dysplasia and early esophageal cancer. The aims of this reviews are as follows: (a) discussing limitations in our current strategies to identify esophageal dysplasia and cancer, (b) explaining the concepts behind deep learning and convolutional neural networks using language appropriate for clinicians without an engineering background, (c) systematically reviewing the literature for studies that have used deep learning to identify esophageal neoplasia, and (d) based on the systemic review, outlining strategies on further work necessary before these technologies are ready for "prime-time," i.e., use in routine clinical care.

Towards screening Barrett's oesophagus: current guidelines, imaging modalities and future developments

Barrett's oesophagus is the only known precursor to oesophageal adenocarcinoma (OAC). Although guidelines on the screening and surveillance exist in Barrett's oesophagus, the current strategies are inadequate. Oesophagogastroduodenoscopy (OGD) is the gold standard method in screening for Barrett's oesophagus. This invasive method is expensive with associated risks negating its use as a current screening tool for Barrett's oesophagus. This review explores current definitions, epidemiology, biomarkers, surveillance, and screening in Barrett's oesophagus. Imaging modalities applicable to this condition are discussed, in addition to future developments. There is an urgent need for an alternative non-invasive method of screening and/or surveillance which could be highly beneficial towards reducing waiting times, alleviating patient fears and reducing future costs in current healthcare services. Vibrational spectroscopy has been shown to be promising in categorising Barrett's oesophagus through to high-grade dysplasia (HGD) and OAC. These techniques need further validation through multicentre trials.

Risk Prediction Models for Barrett's Esophagus Discriminate Well and Are Generalizable in an External Validation Study

BACKGROUND

Barrett's esophagus is the precursor to the highly lethal esophageal adenocarcinoma. Risk prediction models have been developed to assist in its detection, potentially improving early identification and treatment of esophageal adenocarcinoma. Six models have been developed.

AIMS

To externally validate three models (Rubenstein, Thrift, and Baldwin-Hunter models) and compare them to a fourth risk prediction model (Ireland model) for Barrett's esophagus.

METHODS

Data from 120 Barrett's cases and 235 population controls were available to externally validate the three models. Discriminatory ability of these models was assessed by the area under the receiver operating characteristic curve. Calibration was assessed with the calibration slope, Hosmer-Lemeshow test, and Lowess smoother calibration plot. Following external validation, diagnostic accuracy of the three models was compared to that of the Ireland model.

RESULTS

On external validation, the Rubenstein model had an area under the receiver operating characteristic curve of 0.71 and was well calibrated (Hosmer-Lemeshow test, p = 0.67). Likewise, the Thrift and Baldwin-Hunter models had similar discrimination (0.71 and 0.70, respectively) and were also well calibrated (p = 0.69 and p = 0.28). Our previous external validation of the Ireland model provided an area under the receiver operating characteristic curve of 0.83 and was well calibrated (p = 0.14). The Ireland model demonstrated a statistically significantly greater area under the receiver operating characteristic curve than the Rubenstein (p = 0.02), Thrift (p = 0.001), and Baldwin-Hunter (p = 0.002) models.

CONCLUSION

We externally validated the Rubenstein, Thrift, and Baldwin-Hunter risk prediction models and compared them to the Ireland model. The Ireland model demonstrated improved accuracy, albeit with slightly poorer calibration.

Is Routine Preoperative Esophagogastroduodenoscopy Prior to Bariatric Surgery Mandatory? Systematic Review and Meta-analysis of 10,685 Patients

BACKGROUND

This systematic review and meta-analysis searched, retrieved and synthesized the evidence as to whether preoperative esophagogastroduodenoscopy (p-EGD) should be routine before bariatric surgery (BS).

METHODS

Databases searched for retrospective, prospective, and randomized (RCT) or quasi-RCT studies (01 January 2000-30 April 2019) of outcomes of routine p-EGD before BS. STROBE checklist assessed the quality of the studies. P-EGD findings were categorized: Group 0 (no abnormal findings); Group 1 (abnormal findings that do not necessitate changing the surgical approach or postponing surgery); Group 2 (abnormal findings that change the surgical approach or postpone surgery); and Group 3 (findings that signify absolute contraindications to surgery). We assessed data heterogeneity and publication bias. Random effect model was used.

RESULTS

Twenty-five eligible studies were included (10,685 patients). Studies were heterogeneous, and there was publication bias. Group 0 comprised 5424 patients (56%, 95% CI: 45-67%); Group 1, 2064 patients (26%, 95% CI: 23-50%); Group 2, 1351 patients (16%, 95% CI: 11-21%); and Group 3 included 31 patients (0.4%, 95% CI: 0-1%).

CONCLUSION

For 82% of patients, routine p-EGD did not change surgical plan/ postpone surgery. For 16% of patients, p-EGD findings necessitated changing the surgical approach/ postponing surgery, but the proportion of postponements due to medical treatment of H Pylori as opposed to "necessary" substantial change in surgical approach is unclear. For 0.4% patients, p-EGD findings signified absolute contraindication to surgery. These findings invite a revisit to whether p-EGD should be routine before BS, and whether it is judicious to expose many obese patients to an invasive procedure that has potential risk and insufficient evidence of effectiveness. Further justification is required.

Is routine preoperative esophagogastroduodenscopy prior to bariatric surgery mandatory? protocol for a systematic review and meta-analysis

INTRODUCTION

Routine preoperative esophagogastroduodenscopy (p-EGD) prior to bariatric surgery (BS) is currently widely undertaken, and hence an important issue with many clinical and financial repercussions. Yet, the true extent of why p-EGD is routinely undertaken for all bariatric patients remains not well understood.

METHODS AND ANALYSIS

To address this, we will undertake a systematic review and meta-analysis of routine p-EGD prior to BS from around the world. This protocol describes the methodological approach to be adopted and outlines the search strategies and eligibility criteria that will be employed to identify and select studies, and the way by which data from the selected studies will be extracted for analysis. PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), WHO International Clinical Trials Registry Platform, Cochrane Library, MEDLINE, Scopus, clinicaltrials.gov and Google scholar will be searched from 01 January 2000 to 30 April 2019 for original studies written in English that provided prevalence estimates of the outcomes of routine p-EGD prior to BS. STROBE criteria will assess the methodological quality of the selected studies. The use of fixed or random effects model will depend on the results of statistical tests for heterogeneity. Publication bias will be visually estimated by assessing funnel plots. Pooled estimates will be calculated. This protocol conforms to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines and has been submitted for registration at the PROSPERO International Prospective Register of systematic reviews. No ethical clearance is required for this study. This review will be published in a peer- reviewed journal and will be presented at various national and international conferences.

Volumetric laser endomicroscopy in Barrett's esophagus: ready for primetime

Barrett's esophagus (BE) is the condition where intestinal metaplastic changes are found in the normal stratified squamous epithelium of the esophagus predisposing an individual to dysplasia and esophageal adenocarcinoma (EAC). It tends to affect males and is often the result of chronic gastroesophageal reflux disease (GERD). The current standard of therapy for diagnosing Barrett's is white light endoscopy (WLE) with biopsies obtained using the Seattle protocol. Multiple newer advanced modalities have been developed to improve diagnostic abilities, including volumetric laser endomicroscopy (VLE). This technique utilizes second generation optical coherence tomography (OCT) to provide an enhanced circumferential image to a depth of 3 mm with the potential for improved diagnostic yield for dysplasia, particularly submucosal lesions or lesions not seen by WLE. It has also been evaluated in guiding mapping of endotherapy as well as post therapy surveillance for recurrence. Although the results have been promising when used with current diagnostic standards, overall data are limited to support the routine use of VLE.

Screening for esophageal adenocarcinoma and precancerous conditions (dysplasia and Barrett's esophagus) in patients with chronic gastroesophageal reflux disease with or without other risk factors: two systematic reviews and one overview of reviews to inform a guideline of the Canadian Task Force on Preventive Health Care (CTFPHC)

BACKGROUND

Two reviews and an overview were produced for the Canadian Task Force on Preventive Health Care guideline on screening for esophageal adenocarcinoma in patients with chronic gastroesophageal reflux disease (GERD) without alarm symptoms. The goal was to systematically review three key questions (KQs): (1) The effectiveness of screening for these conditions; (2) How adults with chronic GERD weigh the benefits and harms of screening, and what factors contribute to their preferences and decision to undergo screening; and (3) Treatment options for Barrett's esophagus (BE), dysplasia or stage 1 EAC (overview of reviews).

METHODS

Bibliographic databases (e.g. Ovid MEDLINE®) were searched for each review in October 2018. We also searched for unpublished literature (e.g. relevant websites). The liberal accelerated approach was used for title and abstract screening. Two reviewers independently screened full-text articles. Data extraction and risk of bias assessments were completed by one reviewer and verified by another reviewer (KQ1 and 2). Quality assessments were completed by two reviewers independently in duplicate (KQ3). Disagreements were resolved through discussion. We used various risk of bias tools suitable for study design. The GRADE framework was used for rating the certainty of the evidence.

RESULTS

Ten studies evaluated the effectiveness of screening. One retrospective study reported no difference in long-term survival (approximately 6 to 12 years) between those who had a prior esophagogastroduodenoscopy and those who had not (adjusted HR 0.93, 95% confidence interval (CI) 0.58-1.50). Though there may be higher odds of a stage 1 diagnosis than a more advanced diagnosis (stage 2-4) if an EGD had been performed in the previous 5 years (OR 2.27, 95% CI 1.00-7.67). Seven studies compared different screening modalities, and showed little difference between modalities. Three studies reported on patients' unwillingness to be screened (e.g. due to anxiety, fear of gagging). Eleven systematic reviews evaluated treatment modalities, providing some evidence of early treatment effect for some outcomes.

CONCLUSIONS

Little evidence exists on the effectiveness of screening and values and preferences to screening. Many treatment modalities have been evaluated, but studies are small. Overall, there is uncertainty in understanding the effectiveness of screening and early treatments.

SYSTEMATIC REVIEW REGISTRATIONS

PROSPERO (CRD42017049993 [KQ1], CRD42017050014 [KQ2], CRD42018084825 [KQ3]).