Objects: Although a recent study showed the cancer incidence of Barrett's esophagus (BE) to be 1.2%/year in 251 patient-years in Japan, the long-term outcomes remain unclear. The present study estimated the cancer risk of BE in Japan using our original prospective multicenter cohort. Methods: A total of 98 patients with BE of maximum length of ≥2 cm were enrolled during the period of 2010–2012 and received at least one follow-up endoscopy over 5 years thereafter. Cancer incidence rates with 95% confidence interval for occurrence of esophageal adenocarcinoma (EAC) were calculated as the number of events divided by patient-years of follow-up and were expressed as %/year. Results: Overall, the median endoscopic follow-up period was 59.9 (first and third quartiles, 48.5–60.8) months, constituting a total of 427 patient-years of observation. Since two EAC cases developed, the cancer incidence was 0.47% (0.01%–1.81%)/year. The cancer incidence was 0.39% (−0.16% to 2.44%) in 232 patient-years and 0.31% (−0.13% to 1.95%)/year in 318 patient-years for 55 cases with specialized intestinal metaplasia and 70 with BE ≥3 cm (maximum), respectively. At the end of follow-up, 12 of 92 patients (13.0%) died, but none died from EAC. Conclusion: This is the largest prospective follow-up study with endoscopy to investigate the incidence of EAC in unequivocal BE with the maximum length of ≥2 cm in Japan. Although a further large-scale study will be required to validate our results, the cancer risk of BE in Japan would be lower than previously reported (0.47% vs 1.2%/year).
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