With rates of esophageal cancer having quadrupled since the 1970s and fewer than 20% of patients surviving five years post-diagnosis, early detection is more critical than ever. The capsule sponge test offers a powerful tool for risk stratification, ensuring that high-risk individuals continue receiving endoscopy while sparing low-risk patients from unnecessary invasive procedures.The gold standard for monitoring patients at risk of esophageal (throat) cancer has been the endoscopy—a procedure that, while effective, is invasive, uncomfortable, and resource-intensive. Now, a simple device known as the “pill-on-a-string” or capsule sponge test is emerging as a transformative alternative, promising to make screening and surveillance for throat cancer faster, less invasive, and more accessible for millions worldwide.The concept is ingeniously simple: patients swallow a small capsule attached to a string. Once in the stomach, the capsule dissolves, releasing a sponge that expands to about the size of a coin. Healthcare professionals then gently pull the sponge back up by the string, allowing it to collect cells from the lining of the esophagus as it travels upward. The entire procedure takes about ten minutes and can be performed by a nurse in a clinic or even a mobile screening van.Barrett’s esophagus is a chronic condition in which prolonged acid reflux damages the lining of the esophagus. Over time, the damaged cells can become precancerous, forming dysplasia, and potentially progressing into esophageal adenocarcinoma—a type of throat cancer with notoriously poor survival rates. Despite the relatively low annual conversion rate from Barrett’s to cancer (approximately 0.5%), regular monitoring is essential.Traditionally, endoscopy has been the go-to method for this surveillance. However, it is not without drawbacks: sedation, fasting, potential complications, and significant cost. This is where the pill-on-a-string method is poised to transform care—making monitoring more accessible, efficient, and patient-friendly.What Is the Pill-on-a-String Test?The new test involves swallowing a capsule containing a compressed sponge. Once it reaches the stomach, the capsule dissolves, allowing the sponge to expand. Attached to a string, the sponge is gently pulled back up through the esophagus, collecting cells from the lining along the way. These cells are then analyzed in a lab for red-flag changes indicative of dysplasia or early cancer.Though the idea may initially sound uncomfortable, the experience has proven to be far more tolerable than an endoscopy. For Duncan Cook, a 57-year-old heating engineer from Cambridge, who has endured nearly two decades of endoscopic monitoring, the change was welcome.“The first time I had the sponge, I was a bit nervous,” Cook shared in a news release. “It’s quite a big pill to swallow, but it’s much better than going for endoscopies... I was able to have the test done and go right back to work after.”A major challenge is that symptoms often overlap with benign conditions like heartburn, leading to late diagnoses when treatment options are limited. Early detection is critical: when caught at stage 1, five-year survival rates can reach 63%. This is why regular surveillance of high-risk individuals—particularly those with Barrett’s esophagus—is so important.In a large multi-center trial involving 910 patients across 13 hospitals in the U.K., researchers from the University of Cambridge and Queen Mary University of London evaluated the effectiveness of the capsule sponge test. Participants—all of whom were already being monitored for Barrett’s esophagus—underwent both the new test and a standard endoscopy for comparison. Findings from the study, recently published in The Lancet, are compelling:54% of patients were classified as low-risk after the sponge test, showing no cellular changes that could indicate progression to cancer.Only 0.4% of the low-risk group were later found via endoscopy to have high-risk cell changes.No cancers were detected in those flagged as low-risk by the sponge test.These results suggest that more than half of the patients undergoing routine endoscopies could safely switch to the capsule test without compromising diagnostic accuracy.“Our findings suggest that the capsule sponge could help stratify patients with Barrett’s esophagus by risk,” said Dr. Peter Sasieni, director of the Cancer Research UK Cancer Prevention Trials Unit. “Given the low risk of progression in these individuals, it should be safe to replace their usual endoscopy with the capsule sponge.”The research team isn’t stopping here. Scientists are now working to refine the sponge test further by enhancing laboratory analysis of the collected cell samples. Artificial intelligence (AI) is being evaluated to assist in identifying early signs of dysplasia, potentially boosting accuracy and reducing human error.Professor Rebecca Fitzgerald, director of the Early Cancer Institute at Cambridge, noted, “We need an alternative surveillance method that’s less invasive, easier to administer and more reliable… Endoscopies aren’t always a reliable way of spotting early cancers, and they depend on the skill of the person doing it."