Predictive biomarkers for Barrett's esophagus: so near and yet so far

Barrett's esophagus (BE) is the strongest risk factor for the development of esophageal adenocarcinoma. However, the risk of cancer progression is difficult to ascertain in individuals, as a significant number of patients with BE do not necessarily progress to esophageal adenocarcinoma. There are several issues with the current strategy of using dysplasia as a marker of disease progression. It is subject to sampling error during biopsy acquisition and interobserver variability among gastrointestinal pathologists. Ideal biomarkers with high sensitivity and specificity are needed to accurately detect high-risk BE patients for early intervention and appropriate cost-effective surveillance. To date, there are no available molecular tests in routine clinical practice despite known genetic and epigenetic aberrations in the Barrett's epithelium. In this review, we present potential biomarkers for the prediction of malignant progression in BE. These include markers of genomic instability, tumor suppressor loci abnormalities, epigenetic changes, proliferation markers, cell cycle predictors, and immunohistochemical markers. Further work in translating biomarkers for routine clinical use may eventually lead to accurate risk stratification.

Medical and endoscopic management of high-grade dysplasia in Barrett's esophagus

The management of high-grade dysplasia in Barrett's esophagus has clearly changed over recent years. The risk of cancer development is still substantial, with about one in three patients developing cancer, but a number of patients do not develop cancer. The nature of high-grade dysplasia has also been genetically elucidated with more evidence of chromosomal instability being present at this stage than previously thought. Therapy of the condition has evolved more toward endoscopic therapy, given the good results of radio-frequency ablation and photodynamic therapy in eliminating dysplasia and decreasing cancer development in randomized controlled trial. The best candidates for treatment include compliant patients that have relatively short segments of Barrett's esophagus, an anatomically straight segment, lack of nodularity, and an intact p16. However, even with excellent long-term results similar to surgical resection, the risk of recurrence is present in over 14% of patients, which indicates that there will be a need to continue surveillance endoscopy in these patients.

Photodynamic therapy for Barrett's esophagus: does light still have a role?

Photodynamic therapy was the first treatment to have been shown to significantly decrease high-grade dysplasia and cancer in patients with Barrett's esophagus. However, its use has been limited, primarily because of the side effects, which include esophageal strictures, cutaneous photosensitivity, chest pain, and nausea and vomiting. The tolerability aspects of photodynamic therapy, as well as the dosimetry, though, can be improved with existing technologies to further develop this therapy into truly a widely applicable therapy. Studies have recently been done to help identify patients more likely to suffer stricture after photodynamic therapy. In addition there has been evidence to suggest that the efficacy of photodynamic therapy also can be limited by genetic abnormalities in the mucosa. By combining knowledge of tissue biology, optical properties of the tissue, and dosimetry issues with ablation, photodynamic therapy can still have a potentially bright future.