‘Pill on a String’ to Detect Esophageal Cancer

• Barrett esophagus, also called Barrett’s esophagus (BE), can be a precursor to esophageal adenocarcinoma — the most common type of esophageal cancer in Canada. Identifying individuals with BE allows them to be monitored, and if necessary, treated to remove abnormal cells and reduce their risk for developing esophageal cancer.
• Endoscopy and biopsy, the standard for identifying BE, is an expensive procedure that is uncomfortable for patients, requires sedation, and carries some risks.
• The Cytosponge is a small mesh sponge within a soluble gelatin capsule that can safely be administered orally by a nurse in primary care settings to collect esophageal cells for analysis. In combination with biomarker analysis, the Cytosponge has good sensitivity and specificity for detecting individuals likely to have BE.
• Use of the Cytosponge with biomarker analysis could improve identification of individuals with BE through a test that is less onerous for patients than endoscopy, as well as less costly.

Retiree Tony Richards survived cancer of the esophagus and gets an endoscopy every year to look for any sign of cancer’s return. Richards says the endoscopy procedure — where medics insert a camera-enabled tube-like device down an often sedated patient’s throat to collect esophagus cells — would take him out of commission for the day.

“It’s not a very pleasant process,” Richards says.

That’s why Cytosponge is such an exciting news for patients like Richard.

The Technology

The Cytosponge (Medtronic GI Solutions) is a single-use device used to collect cells from the lining of the esophagus. It consists of a small mesh sponge, about 30 mm in diameter, contained in a gelatin capsule and attached to a string. The patient swallows the capsule with water and the gelatin coating dissolves once the Cytosponge reaches the stomach. The patient may be offered a lidocaine throat spray to reduce discomfort. After approximately five minutes, the health care provider uses the string to retrieve the expanded sponge. As it is retrieved, the slightly abrasive mesh collects cells along the length of the esophagus. The collected cells are analyzed using immunohistochemical staining to detect a biomarker that has been validated as an indicator of BE: Trefoil factor 3 (TFF3).

“The sponge contains about half a million cells,” says lead researcher, Professor Rebecca Fitzgerald of the MRC Cancer Unit at the University of Cambridge. Fitzgerald says the sponge technique collects a more representative and comprehensive sweep of cells in the esophagus than an endoscopy, that snips cells from the esophagus wall. “If you directly compare the [Cytosponge] results to endoscopy, it’s accurate to 80 to 90 percent of the time,” Fitzgerald says.

Doctors tested the Cytosponge on more than a thousand people. The trial results claim more than 94 percent of the patients who swallowed the sponge reported no serious side effects. Researchers say patients who were not sedated for an endoscopy procedure were more likely to rate the Cytosponge as “a preferable experience.”

Richards, who took part in the trial, says the Cytosponge is a nice alternative to the endoscopy. “Well, I think it is a no-brainer because the sponge test is so much easier,” he says.

Medics say a traditional endoscopy costs around $900 per procedure. Fitzgerald says the sponge technique costs less than a hundred dollars. In a statement, British cancer charity Cancer Research UK said the Cytosponge trial results are very encouraging. “It will be good news if such a simple and cheap test can replace endoscopy,” said Dr. Julie Sharp, the organization’s head of health information.

Doctors hope to start offering the sponge to patients in Britain sometime next year and say it could become available in the United States within three years.