Preliminary results from a prospective multicenter study of 618 patients show that the prevalent cancer risk within 1 year of diagnosing the index lesion was 6.7% (Clin. Gastroenterol. Hepatol. 2006;4:566–72). Furthermore, when the researchers followed the patients, the risk of cancer in patients with no dysplasia was 0.5% per year while the risk of cancer in patients with low-grade dysplasia was similar at 0.6% per year.
So far, regression of low-grade dysplasia has occurred in 66% of patients. Dr. Canto pointed out that 53% of the incident high-grade dysplasias or cancers developed after two EGDs with no dysplasia. “So what if you have the patient back at year 5 according to the AGA guidelines, but the patient developed a Barrett's cancer or high-grade dysplasia in year 2?” she asked. “We don't have the evidence for increasing the surveillance intervals. In fact, preliminary evidence from this paper suggests that Barrett's high-grade dysplasia or cancer might be missed if you followed the AGA guidelines.”
Screening for Barrett's esophagus and associated neoplasia presents another quagmire. The ACG guidelines state that patients with chronic GERD symptoms are most likely to have Barrett's esophagus and should undergo upper endoscopy, but an AGA technical review concluded that there is no direct evidence that has validated the use of screening for esophageal cancer in the United States.
Dr. Canto said that this is in part because 40% of Barrett's patients with cancer have no GERD symptoms and fewer than 4% have Barrett's diagnosed before the cancer is diagnosed.
One study concluded that screening 50-year-old men with symptoms of GERD to detect adenocarcinoma associated with Barrett's esophagus is probably cost effective, but continuing surveillance of patients who have Barrett's esophagus but no dysplasia is costly, even if screening occurs at 5-year intervals (Ann. Intern. Med. 2003;138:176–86).
Candidates for screening include patients with erosive esophagitis, those with chronic severe GERD, white males over age 50 regardless of symptoms, those with a family history of Barrett's and adenocarcinoma, those who are obese, and postcholecystectomy patients (Am. J. Gastroenterol. 2004;99:2107–14).
Current endoscopic tools for screening include a standard videoendoscope (sedated or unsedated), an unsedated thin videoendoscope, an office-based thin battery-powered endoscope, and wireless capsule endoscopy.
Histology slide shows low-grade dysplasia in a biopsy sample obtained from a patient with Barrett's esophagus. Courtesy Dr. Marcia Irene Canto