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Background--The incidence of oesophageal adenocarcinoma has increased greatly. Barrett's oesophagus is a known risk factor.
Aims--To identify changes in the incidence, prevalence, and outcome of Barrett's oesophagus in a defined population.
Subjects--Residents of Olmsted County, Minnesota, with clinically diagnosed Barrett's oesophagus, or oesophageal or oesophagogastric junction adenocarcinoma.
Methods--Cases were identified using the Rochester Epidemiology Project medical records linkage system. Records were reviewed with follow up to 1 January 1998.
Results--The incidence of clinically diagnosed Barrett's oesophagus ([greater than]3 cm) increased 28-fold from 0.37/100 000 person years in 1965-69 to 10.5/100 000 in 1995-97. Of note, gastroscopic examinations increased 22-fold in this same time period. The prevalence of diagnosed Barrett's oesophagns increased from 22.6 (95% confidence interval (CI) 11.7-33.6) per 100 000 in 1987 to 82.6/100 000 in 1998. The prevalence of short segment Barrett's oesophagus ([less than]3 cm) in 1998 was 33.4/100 000. Patients with Barrett's oesophagus had shorter than expected survival but only one patient with Barrett's oesophagus died from adenocarcinoma. Only four of 64 adenocarcinomas occurred in patients with previously known Barrett's oesophagus.
Conclusions--The incidence and prevalence of clinically diagnosed Barrett's oesophagus have increased in parallel with the increased use of endoscopy. We infer that the true population prevalence of Barrett's oesophagus has not changed greatly, although the incidence of oesophageal adenocarcinoma increased 10-fold. Many adenocarcinomas occurred in patients without a previous diagnosis of Barrett's oesophagus, suggesting that many people with this condition remain undiagnosed in the community.
Keywords: Barrett's oesophagus; oesophageal adenocarcinoma; adenocarcinoma of cardia; epidemiology; gastroscopy; gastro-oesophageal reflux disease
The incidence of adenocarcinoma of the oesophagus and oesophagogastric junction has increased greatly in western countries since about 1970, especially in white males. [1-4] The cause of the increase is unknown, although risk factors including smoking, obesity, and a history of gastro-oesophageal reflux disease have been identified, [5-9] and an inverse relationship to the declining prevalence of Helicobacter pylori has been noted.  The outlook for patients with oesophageal adenocarcinoma is poor; one review showed five year survival of 17% after surgical resection and [less than]1% for unresectable tumours. 
Most oesophageal adenocarcinomas arise in a Barrett's oesophagus. [12 13] Adenocarcinoma of the oesophagogastric junction may arise in short or long segments of Barrett's oesophagus. [12-14] In Barrett's oesophagus, the squamous epithelium of the distal oesophagus, damaged by gastro-oesophageal reflux, is replaced by columnar epithelium." [15 16] In Barrett's oesophagus, there is an estimated 30-52 times increased risk of developing oesophageal cancer.  Patients with Barrett's oesophagus are usually advised to have periodic endoscopy and biopsy [17 18] for early detection of malignancy.
It is not clear if the increasing incidence of adenocarcinoma is due to a greater prevalence of Barrett's oesophagus, a greater risk of malignant transformation in Barrett's oesophagus, or mechanisms unrelated to Barrett's oesophagus. We sought to address this issue by examining trends in the incidence, prevalence, and outcome of Barrett's oesophagus in a defined population.
Materials and methods
Population based research is feasible in Olmsted County, Minnesota, because medical care is virtually self contained within the community and there are relatively few providers. The major institution is the Mayo Clinic which has maintained a common medical record with its two affiliated hospitals for over 90 years. Recorded diagnoses and surgical procedures (including endoscopy) are indexed, including diagnoses made for outpatients seen in office or clinic consultations, emergency room visits, or nursing home care, and diagnoses recorded for hospital inpatients, autopsies, or on death certificates. Medical records of other providers serving the local population, especially the Olmstead Medical Center with its affiliated hospital, are also indexed and retrievable. Thus details of the medical care of county residents are available through this linked records system, as described elsewhere.