Barrett’s esophagus is the only known precursor of esophageal adenocarcinoma. Although endoscopy and biopsy are standard methods for diagnosing Barrett’s esophagus, their high cost and risk limit their use as a screening modality. Researchers sought to develop a screening method based on methylation status in cytology samples captured by a tool called the EsophaCap. Their findings were published by Wang et al in Clinical Cancer Research.
Senior study author Stephen Meltzer, MD, Professor of Medicine and Oncology at the Johns Hopkins University School of Medicine, along with a team of researchers, clinicians, and biomedical engineers, tested the EsophaCap, which uses specific genetic biomarkers to detect dangerous changes in the cells that line the inside of the esophagus. Previous studies have demonstrated the biomarkers’ ability to detect Barrett’s esophagus, which causes the body to replace the tissue that lines the organ with cells that can turn cancerous. Large-scale methods to deploy those biomarkers as a screening tool have been elusive.
The principle behind the EsophaCap is simple, said Dr. Meltzer. The patient swallows a small capsule with a long string attached to it. After the capsule makes its way down the esophagus and into the stomach—a process that takes only a minute or so—the gelatin coating on the capsule begins to dissolve. From the initial capsule, a 2-cm polyurethane sponge emerges, still attached to the string, much of which still hangs from the patient's mouth.
The screener gently pulls the string, and the sponge begins its return journey—out of the stomach, into the esophagus, and, finally, out of the patient's mouth. As it makes its way up, the sponge comes into contact with the entire length and breadth of the esophagus, collecting genetic material along the way. As the sponge nears the top of the esophagus, the screener gives a final gentle tug, popping the sponge past the organ's upper sphincter muscle. The sponge emerges loaded with genetic material that holds the key to the patient’s esophageal health and is then sent for simple genetic tests on the material to determine the patient’s risk for esophageal cancer.
“Early detection is the whole ballgame when it comes to esophageal cancer,” said Dr. Meltzer in a statement. “Patients have a much better chance to treat it—or even prevent it—if they know their risk. We believe this little sponge can bring easy and inexpensive screening to people around the world.”
In previous research, Dr. Meltzer has performed rigorous testing on the set of genetic biomarkers he uses to diagnose Barrett’s esophagus. The gene combination of p16, NELL1, AKAP12, and TAC1 has yielded a sensitivity of nearly 92% and has offered reliable diagnoses.
Dr. Meltzer administered the EsophaCap test to 94 people over the course of the study. About 85% of study participants were able to swallow the capsule, with 100% successful sponge retrieval. Endoscopic evaluation of the patients after EsophaCap administration showed no evidence of bleeding, pain, trauma, or other adverse reactions to the test.
Researchers reported that of the patients able to swallow the capsule, nearly half were diagnosed with Barrett’s esophagus—a rate far higher than that found in the general U.S. population. Most patients enrolled in the study were being treated for gastrointestinal symptoms. “That may explain why we saw a rate of Barrett’s esophagus that was higher than in the general population,” said Dr. Meltzer.
The area under the curve for the EsophaCap was 0.894, with a sensitivity of 94.4% and a specificity of 62.2% in the training set.
Disclosure: The study authors’ full disclosures can be found at clincancerres.aacrjournals.org.
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