Barrett Esophagus May Progress to Cancer Less Often than Thought
The risk of Barrett esophagus (BE) developing into esophageal cancer may be lower than previously thought, according to one of the largest studies of its kind. The study was conducted in Ireland, where the clinical parameters for diagnosing BE are different than they are in the United States. As a result, the implications of these results for care in the United States are unclear. The study was published online June 16 in the Journal of the National Cancer Institute.
Esophageal cancer incidence has been rising dramatically in the United States, with an increase of 300 to 400 percent in the last 30 years. BE is a strong risk factor for the development of esophageal cancer. Current clinical guidelines advise that people who have BE without evidence of significant cellular aberrations, known as dysplasia, undergo an endoscopy every 3 to 5 years, with more frequent endoscopies in people whose BE has more significant dysplasia.
In this study, researchers followed more than 8,500 BE patients who were listed in the Northern Ireland Barrett Esophagus Registry. After a mean follow-up of 7 years, 79 participants had been diagnosed with esophageal cancer, 16 with cancer of the gastric cardia (the junction between the esophagus and stomach), and 36 with high-grade dysplasia, meaning that the esophageal tissue had severe precancerous changes. The combined incidence of all three outcomes was 0.22 percent per year, lower than what has been seen in previous studies. Consistent with previous studies, cancer risk was higher among men and in patients over 50 years of age.
In addition to showing a lower risk of progression than previously seen, the study “makes it possible to more accurately determine risk in subgroups and to estimate changes in risk of progression over time,” wrote the study’s lead investigator, Dr. Shivaram Bhat of Queen’s University Belfast, and his colleagues.
However, only 46 percent of the BE patients in the registry had changes in the esophageal lining (identified during an endoscopy) known as specialized intestinal metaplasia (SIM), a condition which is used to diagnose BE in the United States. The remaining patients had been diagnosed with BE based on the presence of less severe changes to the esophageal lining, determined via a biopsy. The combined incidence of progression from BE to esophageal cancer, gastric cardia cancer, or high-grade dysplasia in patients with SIM was 0.38 percent per year. Patients without SIM at their first biopsy had a much lower incidence of progression, just 0.07 percent per year.
Diagnosing BE in patients without SIM “could meaningfully bias the results,” wrote Dr. Douglas Corley of the Kaiser Permanente Northern California Division of Research in an accompanying editorial. In the patients with SIM, he noted, the incidence of progression to cancer was only slightly lower than prior estimates. “The current study…provides general support for many paradigms underlying current thoughts about the management of Barrett esophagus,” explained Dr. Corley. Further studies will be necessary to determine “whether surveillance or treatment actually decrease cancer deaths and the development of better techniques for risk stratification.”
The conflicting diagnostic criteria for BE “makes it difficult to compare these results with other studies,” agreed Dr. Asad Umar of NCI’s Division of Cancer Prevention. The findings, he continued, “need to be analyzed with caution, as the practice of endoscopic and pathologic evaluations varies greatly among practices and research groups.”
NCI Cancer Bulletin for June 28, 2011 - National Cancer Institute