Buried metaplasia after endoscopic ablation of Barrett's esophagus: a systematic review

Abstract

Objectives: Endoscopic ablation of Barrett's esophagus can bury metaplastic glands under a layer of neosquamous epithelium. To explore the frequency and importance of buried metaplasia, we have conducted a systematic review of reports on endoscopic ablation.

Methods: We performed computerized and manual searches for articles on the results of photodynamic therapy (PDT) and radiofrequency ablation (RFA) for Barrett's esophagus. We extracted information on the number of patients treated, biopsy protocol, biopsy depth, and frequency of buried metaplasia.

Results: We found 9 articles describing 34 patients with neoplasia appearing in buried metaplasia (31 after PDT). We found five articles describing a baseline prevalence of buried metaplasia (before ablation) ranging from 0% to 28%. In 22 reports on PDT for 953 patients, buried metaplasia was found in 135 (14.2%); in 18 reports on RFA for 1,004 patients, buried metaplasia was found in only 9 (0.9%). A major problem limiting the conclusions that can be drawn from these reports is that they do not describe specifically how frequently biopsy specimens contained sufficient subepithelial lamina propria to be informative for buried metaplasia.

Conclusions: Endoscopic ablation can bury metaplastic glands with neoplastic potential but, even without ablation, buried metaplasia often is found in areas where Barrett's epithelium abuts squamous epithelium. Buried metaplasia is reported less frequently after RFA than after PDT. However, available reports do not provide crucial information on the adequacy of biopsy specimens and, therefore, the frequency and importance of buried metaplasia after endoscopic ablation remain unclear.

Figure 1

Flowchart of the literature search. AF, all searchable fields; MeSH, medical subject heading; PDT, photodynamic therapy; RFA, radiofrequency ablation.

Figure 2

Endoscopic photograph of Barrett's esophagus using narrow band imaging. The metaplastic columnar (Barrett's) epithelium is dark, and the squamous epithelium is light. Notice the squamous islands, which presumably develop as a consequence of biopsy sampling of metaplastic epithelium during endoscopic surveillance.

Figure 3

Photomicrograph of a pinch biopsy specimen of neosquamous mucosa showing buried metaplastic glands in the subepithelial lamina propria (H&E, magnification ×40). The blue lines delimit a hypothetical biopsy specimen that contains only the epithelial layer. Note that this hypothetical specimen includes papillae, and so could be categorized as containing “lamina propria.” This categorization belies the true depth of the hypothetical biopsy specimen, because such a specimen is not informative for buried metaplasia.