What does the simultaneous expression of Lewis antigen and sulphomucins tell about patients at risk for dysplasia and carcinoma?
J. Torrado, J. Garay (San Sebastián)
The evolution of adenocarcinoma in the distal esophagus follows a sequence of alterations including reflux esophagitis and Barrett's esophagus of gastric and specialized types [1-3]. Histologically, the specialized type of Barrett's esophagus is analogous to the intestinal metaplasia in the gastric mucosae and also indicates a greater risk of malignant transformation [4-7].
Sulphomucins characterize the so-called colonic or incomplete type of intestinal metaplasia in the stomach . However, the significance of such finding in Barrett's esophagus remains controversial [9-11]. Although we have linked the simultaneous expression of sulphomucins and Lewis a antigen in areas of intestinal metaplasia in the stomach to an increased risk of premalignant progression [12-14], the prevalence and significance of aberrant expression of Lewis a antigen and sulphomucins in Barrett's esophagus have not been explored.
We have studied a group of 155 consecutive patients with Barrett's esophagus (unpublished results) referred at our hospital for upper gastrointestinal endoscopy and biopsy. The specific aims were to correlate the different histological stages of Barrett's esophagus, including adenocarcinoma, with the expression of sulphomucins and aberrant Lewis a antigen.
Table I shows the prevalence of sulphomucins by type of Barrett's esophagus. Cancer patients expressed sulphomucins in columnar cells in specialized-type areas of Barrett's esophagus more often than patients with specialized Barrett's esophagus without cancer (93.8% vs 58.6%, age-adjusted OR = 9.84, p < 0.05).
Table II shows the prevalence of aberrant Lewis a antigen expression in Lewis (a-b+) patients by type of Barrett's esophagus. Cancer patients expressed Lewis a antigen in columnar cells in specialized type areas more often than patients with specialized Barrett's esophagus without cancer (100% vs 35.4%, OR = 63.5, p < 0.001).
While none of the 36 Lewis (a-b+) patients with gastric type of Barrett's esophagus expressed sulphomucins or Lewis a antigen, all nine Lewis (a-b+) patients with cancer expressed both markers. Only 4 (6.2%) of the 65 Lewis (a-b+) with specialized type of Barrett's esophagus expressed neither sulphomucins nor aberrant Lewis a antigen, 6 (9.2%) expressed only the aberrant Lewis a antigen, 20 (30.8%) expressed only sulphomucins and 35 (53.8%) expressed both markers.
In summary, we propose the existence of a specialized type of Barrett's esophagus similar to the incomplete or colonic type of gastric intestinal metaplasia which expresses sulphomucins and aberrant Lewis a antigen in goblet and columnar cells, and is associated with a higher risk of malignant transformation.
3. Reid BJ, Blount PL, Rubin CE, Levine DS, Haggit RC, Rabinovitch PS. Flow-cytometric and histological progression to malignancy in Barrett's esophagus: prospective endoscopic surveillance of a cohort. Gastroenterology 1992;102:1212-1219.
10. Haggitt RC, Reid BJ, Rabinovitch PS, Rubin CE. Barrett's esophagus. Correlation between mucin histochemistry, flow cytometry, and histologic diagnosis for predicting increased cancer risk. Am J Pathol 1988;131:53-61.