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Barrett’s esophagus is a premalignant condition associated with gastroesophageal reflux disease, and consists of mucosa with metaplastic columnar epithelium (specialized columnar epithelium). In this study, we examined immunohistochemical mucin expression and Ki-67 labeling index (LI) of 12 esophageal Barrett’s adenocarcinomas as well as 27 cases of short-segment Barrett’s esophagus (SSBE), and clarify significance of incomplete intestinal metaplasia of Barrett’s mucosa as a premalignant lesion. Gastric mucin (MUC5AC, HGM and/or MUC6) were detected in 91.7% of Barrett’s adenocarcinoma, while MUC-2 and CD10 (markers of intestinal phenotypes) were detected in 66.7% and 33.3%, respectively. Ki-67 LI was 33.4% in Barrett’s adenocarcinoma tissues. In all cases, gastric mucin was found in the non-neoplastic Barrett’s mucosa around the adenocarcinoma. MUC2 was detected in 83.3% of proximal non-neoplastic mucosa and in 100% of distal non-neoplastic mucosa of Barrett’s adenocarcinoma, while CD10 was found in 16.7% of proximal non-neoplastic mucosa and in 28.6% of distal non-neoplastic mucosa of Barrett’s adenocarcinoma. Ki-67 LI was 25.8% in proximal non-neoplastic mucosa and 17.8% in distal non-neoplastic mucosa (p < 0.05). We also analyzed mucin expression and Ki-67 LI in SSBE cases without adenocarcinoma. All 27 SSBE cases showed gastric mucin (MUC5AC, HGM and/or MUC6), while MUC2 and CD10 were detected in 51.9% and 48.1% of SSBE. Ki-67 LI of SSBE positive cases for CD10 was 23.6%, while that of SSBE negative cases for CD10 was 14.4% (p < 0.05). SSBE cases were divided into two groups: one was gastric epithelium type with low Ki-67 LI, and the other was metaplastic epithelium with intestinal metaplasia and high Ki-67 LI. In conclusion, Barrett’s esophagus mucosa with intestinal metaplasia and high Ki-67 LI was suggested to be more important as a premalignant lesion, and predominantly found in the proximal region of Barrett’s esophagus, compared with the distal region.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]