Barrett's Esophagus-3


Esophagus: General
Esophagus: Structure
Esophagus: Function
Barrett's Esophagus-1
Barrett's Esophagus-2
Barrett's Esophagus-3
Photodynamic Therapy




Adenocarcinoma in Barrett esophagus develops in a sequence of changes from nondysplastic or metaplastic columnar epithelium, through low-grade and then high-grade dysplasia and ultimately adenocarcinoma (7).  Thus critical to the pathologic evaluation of patients with Barrett mucosa is the degree of dysplasia, the presumed precursor of malignancy, in columnar epithelium with intestinal metaplasia.  Dysplasia is recognized by the presence of cytologic and architectural abnormalities in the columnar epithelium and can be classified as low-grade or high-grade, with the predominant distinction being a basal orientation of all nuclei in low-grade dysplasia versus nuclei consistently reaching the apex of epithelial cells in high-grade dysplasia.  Approximately 50% of patients with high-grade dysplasia have adjacent adenocarcinoma (8). The molecular pathogenesis of Barrett's esophagus and esophageal adenocarcinoma has been shown to include the accumulation of multiple genetic alterations over time. In Barrett’s esophagus, loss of heterozygosity of such tumor suppressor genes as p53, the adenomatous polyposis coli gene (APC), the gene deleted in colorectal cancer (DCC) and MTS1 (p16) has been demonstrated to correlate with progression from metaplasia to dysplasia to cancer (9). 

There are three primary options once Barrett esophagus has been diagnosed. Patients can undergo aggressive surveillance endoscopy using the Seattle protocol (four quadrant biopsies using jumbo biopsy forceps at 1 cm intervals and biopsy of any mucosal irregularity with a therapeutic endoscope) at 3 month intervals until cancer is identified, or esophagectomy or ablative therapy can be performed. Continued surveillance using the Seattle protocol is largely reserved for poor surgical candidates. Ablation using photodynamic therapy (PDT) is a welcome alternative to esophagectomy for most patients, because esophagectomy is a highly morbid surgery, even in expert centers, with a mortality approaching 5% (10).





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