Posted on March 26th, 2015 by
Screening for Barrett’s esophagus with a new device called a Cytosponge is accurate compared to endoscopy but less expensive and easier on patients. These findings were reported in the journal PLoS Medicine.
Barrett’s esophagus is a pre-cancerous condition of the esophagus. It means that there is a type of cell called columnar epithelial cells present in the surface lining of the lower esophagus. Typically, the surface lining of the lower esophagus should only contain squamous cells; however reflux of stomach contents, especially acid, into the esophagus causes these squamous cells to be replaced by columnar epithelial cells more similar to those found in the stomach and intestines.
Screening for Barrett’s is important because the condition can lead to precancerous changes and potentially cancer. Screening typically involves endoscopy—an examination with an endoscope (a thin, tube-like instrument that’s used to look at tissues inside the body) and routine biopsies every six months to two years. Screening endoscopy, however, is not recommended for routine use due to expense and patient tolerance.
Researchers recently evaluated a new, minimally invasive way to screen for Barrett’s esophagus. This approach would help identify patients who would benefit from endoscopy and spare others from invasive, costly screening. It uses a device called a Cytosponge, which includes a small sponge-like capsule that’s attached to a string. The patient swallows the capsule, which then quickly expands in the stomach. When the capsule is pulled back up, it picks up samples of cells from the esophagus wall. The cells can then be tested for signs of Barrett’s esophagus.
Researchers in the UK conducted a case-control study between 2011 and 2014 to measure how well Cytosponge worked to detect Barrett’s esophagus compared to endoscopy, as well as the device’s safety and tolerability among patients. They studied the screening procedure in 1,110 patients from 11 hospitals and compared its accuracy with that of endoscopy and biopsy. Of these patients, 463 had symptoms of indigestion, heartburn, and reflux (controls), and 647 had been previously diagnosed with Barrett’s esophagus using endoscopy (cases).
The researchers evaluated the screening accuracy of Cytosponge for Barrett’s esophagus using two measures: sensitivity, which means the likelihood that Cytopsonge would give a positive test result in patients who actually had Barrett’s esophagus; and specificity, which means the likelihood that Cytosponge would give a negative test result in patients without the disease.
Almost all of the patients—1,042 or about 94%—were able to swallow the Cytosponge without serious complications. Overall, the patients reported that they preferred Cytopsonge screening to endoscopy. The procedure’s overall sensitivity was acceptable at almost 80%. In individuals with a higher cancer risk, sensitivity increased to about 87%. When 107 patients swallowed the Cytosponge twice during the study, sensitivity rose to almost 90%. These sensitivity rates remained the same when researchers looked separately at patients with precancerous changes. Specificity for Cytosponge was also impressive at about 92%.
Though, according to these findings, screening for Barrett’s esophagus with the Cytosponge device is widely accurate, we can’t assume Cytosponge will have the same outcomes in the general population as it had in this case-control study. Case-control studies compare two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). As a result, case-control studies don’t directly reflect the general population.
Cytosponge will still need to prove its accuracy beyond the case-control setting. A randomized clinical trial—one in which participants are assigned by chance to different screening groups—is needed to measure how Cytosponge might perform in the general population.
Reference: Ross-Innes CS, Debiram-Beecham I, O’Donovan M, et al. Evaluation of a Minimally Invasive Cell Sampling Device Coupled with Assessment of Trefoil Factor 3 Expression for Diagnosing Barrett’s Esophagus: A Multi-Center Case–Control Study. PLoS Medicine. January 29, 2015
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