Transcriptionally active human papillomavirus is strongly associated with Barrett's dysplasia and esophageal adenocarcinoma

Viruses, Other Pathogenic Microorganisms and Esophageal Cancer

BACKGROUND

Esophageal cancer (EC) is the eighth most prevalent malignant tumor and the sixth leading cause of cancer mortality throughout the world. Despite the technical developments in diagnosis and treatment, the 5-year survival rate is still low. The etiology of EC remains poorly understood; multiple risk factors may be involved and account for the great variation in EC incidence in different geographic regions.

SUMMARY

Infection with carcinogenetic pathogens has been proposed as a risk factor for EC. This review explores the recent studies on the association of human papillomavirus (HPV), Epstein-Barr virus (EBV), Helicobacter pylori and esophageal bacterial biota with EC.

KEY MESSAGE

Among the above-mentioned pathogens, HPV most likely contributes to esophageal squamous cell carcinoma (ESCC) in high-risk populations. New techniques are being applied to studies on the role of infection in EC, which will inevitably bring novel ideas to the field in the near future.

PRACTICAL IMPLICATIONS

Multiple meta-analyses support the finding of a higher HPV detection rate in regions associated with high risk for ESCC compared to low-risk areas. A potential role of HPV in the rise of esophageal adenocarcinoma (EAC) was proposed recently. However, further studies are required before a firm conclusion can be drawn. Less work has been done in studying the association between EBV and ESCC, and the results are quite controversial. H. pylori infection is found to be inversely related to EC, which is probably due to the reduced incidence of gastroesophageal reflux disease. Analysis of the esophageal bacterial biota revealed distinct clusters of bacteria in normal and diseased esophagi. A type II microbiome rich in Gram-negative bacteria potentially contributes to EAC by inducing chronic inflammation. Novel findings from such studies as these may benefit public health by justifying anti-infection measures to prevent EC.

Barrett's oesophagus: can meaningful screening and surveillance guidelines be formulated based on new data and rejigging the old paradigm?

Gastro-oesophageal reflux disease (GORD) and Barrett's oesophagus (BO) have been considered to be the most important known risk factors for oesophageal adenocarcinoma (OAC). It has been the fastest growing cancer in the Western World and has occurred against a backdrop of progressive reduction in the risk estimate of malignancy associated with BO and no reduction in mortality from OAC using the prevailing screening and surveillance guidelines. The recently published link between high risk HPV and Barrett's dysplasia/cancer may be the 'missing' strong risk factor responsible for the significant rise of OAC since the 1970's, as has been the case with head and neck tumours, another viral associated cancer. P53 immunohistochemistry has been proposed as a good molecular marker for predicting disease progression in BD. Nevertheless, significant negative staining for this mutation in BD remains a major hurdle to widespread routine clinical use as a sole molecular marker. Recent data raises the distinct possibility of at least 2 (probably more) carcinogenic pathways operating in OAC. One is HPV mediated devoid largely of p53 mutations and the other p53 dependent. The joint use of both these markers as part of a molecular panel may represent the best bet yet of detecting the high risk group of progressors to OAC. Patients who are positive for either or both biomarkers i.e p53 or/and transcriptional markers of HPV may warrant more intensive screening. In future, genome wide technology may provide molecular signatures to aid diagnosis and risk stratification in BO.

Microbiome, innate immunity, and esophageal adenocarcinoma

With the development of culture-independent technique, a complex microbiome has been established and described in the distal esophagus. The incidence of esophageal adenocarcinoma (EAC) has increased dramatically in the United States. Studies documenting an altered microbiome associated with EAC and its precedents suggest that dysbiosis may be contributing to carcinogenesis, potentially mediated by interactions with toll-like receptors. Investigations attempting to associate viruses with EAC have not been as consistent. Currently available data are cross-sectional and therefore cannot prove causal relationships. Prospectively, microbiome studies open a new avenue to the understanding of the etiology and pathogenesis of reflux disorders and EAC.

Infection and esophageal cancer

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on infection and cancer, and includes commentaries on the influence of bacterial infections on mucin expression and cancer risk; the role of esophageal bacterial biota in the incidence of esophageal disease; the association between human papilloma virus (HPV) and esophageal squamous cell carcinoma; the role of HPV in esophageal adenocarcinoma; the role of Helicobacter pylori in cardiac carcinoma; and the role of Epstein-Barr virus infection in esophageal cancer.

Endoscopic surveillance of gastrointestinal premalignant lesions: current knowledge and future directions

PURPOSE OF REVIEW

Provide an evidence-based resource for the surveillance of gastrointestinal premalignant lesions, focusing on the scientific articles reported recently.

RECENT FINDINGS

No randomized controlled clinical trials exist to definitively support the efficacy of surveillance programs for Barrett's esophagus and gastric intestinal metaplasia. However, surveillance of these premalignant lesions is recommended by some of the leading organizations. To optimize the usefulness of surveillance programs, targeting high-risk patients might maximize its benefits. A Barrett's esophagus segment of at least 3 cm and evidence of intestinal metaplasia can help stratify those patients at highest risk for progression to esophageal adenocarcinoma. The location, extent, and severity of intestinal metaplasia are indicators of risk of developing gastric cancer. Patients with extensive intestinal metaplasia should be offered endoscopic surveillance. Quality in the baseline colonoscopy is crucial to decrease the risk of interval colorectal cancers. The importance of serrated polyps, as well as their surveillance intervals, is emphasized.

SUMMARY

To optimize the usefulness of surveillance programs, targeting high-risk patients might maximize its benefits. Future research is needed to design more effective surveillance strategies. Recently, emerging imaging techniques hold promise for improving sensitivity of endoscopic surveillance of premalignant conditions in the gastrointestinal tract.

Barrett's Esophagus

OPINION STATEMENT

Barrett's esophagus (BE) is the most important and recognizable precursor lesion for esophageal adenocarcinoma (EAC), which is the one of the fastest-growing cancers in the Western world (600 % in the U.S. in the last 40 years), and therefore it is critical to manage the risk of cancer present in BE. New developments in imaging and molecular markers, as well as an armamentarium of novel and effective endoscopic eradication therapy - especially radio-frequency ablation (RFA) and endoscopic mucosal resection (EMR) - are now available to the interventional endoscopist to help curb the significant rise of esophageal adenocarcinoma (EAC). Endoscopic surveillance is currently recommended by most gastroenterology societies worldwide, although there is no data to support this practice in relation to reducing mortality from EAC. Paradoxically, the cancer risk in Barrett's esophagus is being progressively downgraded, which raises fundamental questions about our understanding of the risk factors and molecular biology of the Barrett's metaplasia-dysplasia-adenocarcinoma sequence. The recent discovery of a strong association of transcriptionally active high-risk human papillomavirus (hr-HPV) with Barrett's dysplasia (BD) and EAC may shed some light on this anomaly. It is imperative that we identify the high-risk group of progressors to EAC. While p53 immunohistochemistry is currently probably the best clinical molecular marker for predicting disease progression in BD, we must think outside the box and cast the net wide in search of additional biomarkers (e.g., high-risk human papilloma virus (hr-HPV)].

Research advances in esophageal diseases: bench to bedside

Over the last year, significant steps have been made toward understanding the pathogenesis of esophageal diseases and translating this knowledge to clinical practice. Gastroesophageal reflux disease (GERD) is the most common outpatient diagnosis in gastroenterology and has a high prevalence in the general population. As many as 40% of patients with GERD have incomplete response to medical therapy, and the pathophysiological mechanisms underlying lack of response are now better understood. Novel medical and minimally invasive interventions are available to optimize management of GERD. Esophageal cancer, regardless of the histological subtype, has among the worst survival statistics among all malignancies. Taking advantage of technological advances in genome sequencing, the mutational spectra in esophageal cancer are now emerging, offering novel avenues for targeted therapies. Early diagnosis is another strand for improving survival. While genome-wide association studies are providing insights into genetic susceptibility, novel approaches to early detection of cancer are being devised through the use of biomarkers applied to esophageal samples and as part of imaging technologies. Dysmotility and eosinophilic esophagitis are the differential diagnoses in patients with dysphagia. New pathophysiological classifications have improved the management of motility disorders. Meanwhile, exciting progress has been made in the endoscopic management of these conditions. Eosinophilic esophagitis is still a relatively new entity, and the pathogenesis remains poorly understood. However, it is now clear that an allergic reaction to food plays an important role, and dietary interventions as well as biologic agents to block the inflammatory cascade are novel, promising fields of clinical research.