[639] Development of Multilayerd Epithelium (ME) after Photodynamic Therapy (PDT): Does MLE Represent an Inevitable Progression to Barrett's Esophagus (BE)?

F Ogawa, A Srivastava, GY Lauwers, M Mino-Kenudson. Massacusetts General Hospital, Boston, MA; Dartmouth Hitchcock Medical Center, Lebanon, NH

Background: PDT is used to ablate BE and BE-related neoplasia, which then leads to restoration of squamous epithelium, over a variable period of time. ME is a distinctive hybrid-type epithelium with squamous and columnar features that has been observed in association with shorter lengths of BE and is believed to be a precursor to BE. However, ME has also been reported in post-PDT biopsies raising the possibility that ME may represent an intermediate step in the columnar to squamous transition post PDT as well. The aim of this study was to determine the prevalence and significance of ME in pre- and post-PDT biopsies.
Design: The study cohort consisted of 47 BE patients (mean age: 71 years, M:F = 38:9, mean BE length: 6.4 cm) with high-grade dysplasia (n=13), intramucosal adenocarcinoma (n=28) and invasive adenocarcinoma (n=6), all of whom were treated with PDT. All patients were also on proton pump inhibitor therapy. Four quadrant biopsies, every 2 cm, were taken pre and post PDT from the site of the original BE segment. The presence of ME in pre- and post-PDT biopsies was correlated with several clinicopathological features.
Results: ME was found in 4 patients (8.5%) pre PDT and in 24 (51.1%) post PDT. There was a trend towards ME observed more often post PDT (43/456 endoscopies, 9.4%) than pre PDT (4/72, 5.6%). ME was noted only in biopsy levels within 2 cm of GE junction and was often associated with esophageal mucosal glands and/or squamous islands. ME was seen in biopsies performed at an average of 15.7 months after PDT (range: 1 - 63 months). The original BE segment was longer in patients who developed ME post PDT (ME+ group) than in those who did not (ME- group) (7.54cm vs. 5.13cm, respectively, p = 0.01). There was no difference in other clinicopathologic features between the 2 groups. At the end of the follow-up period (mean: 48 months), neoplasia persisted in 10 patients (4 in the ME+ and 6 in the ME- groups, p= 0.36) and residual BE was observed in 15 patients (8 in the ME+ and 7 in the ME- groups, P=0.59).
Conclusions: ME often develops after PDT and is associated with longer BE segment length. The presence of post-PDT ME does not correlate with persistence of BE and/or neoplasia. The results suggest that ME can be seen during the process of squamous restitution (an intermediate step in the columnar to squamous conversion) and that ME does not always represent an inevitable progression to BE.
Category: Gastrointestinal

Monday, March 9, 2009 8:45 AM

Platform Session: Section C, Monday Morning