It remains unclear why Barrett esophagus (BE)-associated adenocarcinoma (EAC) frequently occurs in the 0 to 3 o'clock area of the BE. The aims of this study were to clarify the localization of specialized intestinal metaplasia (SIM) as a precancerous lesion and of molecular alterations among different locations using 4-quadrant biopsies based on the "Seattle" protocol. We prospectively evaluated microsatellite instability; methylation status at the APC, CDKN2A, hMLH1, RUNX3, and MGMT genes; the immunoreactivity of the monoclonal antibody Das-1 for the colonic phenotype; and Ki-67 staining in 10 early EACs and 128 biopsy samples from 32 BE patients. Among the molecular changes, only APC gene hypermethylation was an independent predictive marker of EAC (odds ratio, 24.4; P = .01). SIM was more frequently identified in the 0 to 3 o'clock quadrant than in the 6 to 9 o'clock quadrant (P = .08). The Ki-67 index was higher in SIM than in the columnar-lined epithelium (CLE) without goblet cells (P < .0001) and in both SIM and CLE with Das-1 reactivity than in those without (P = .04 and P = .06, respectively). Furthermore, the index was relatively higher in the 0 to 3 o'clock quadrant than in the 6 to 9 o'clock quadrant in cases with Das-1 reactivity. RUNX3 methylation was more frequently found in SIM than in CLE (P = .04), whereas the incidence of the other biomarkers did not show a significant difference between the 0 to 3 o'clock and 6 to 9 o'clock areas, nor between SIM and CLE. SIM with Das-1 reactivity, but not molecular alterations, in the 0 to 3 o'clock quadrant may have higher proliferative activity compared to the other areas of the BE.
Keywords: Barrett's esophagus; Columnar-lined epithelium; Das-1; Methylation; Microsatellite instability; Specialized intestinal metaplasia.
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