Sponge on a String – Detecting a Lethal Cancer
Esophageal cancer can be lethal. When diagnosed after the onset of symptoms, only 20% of patients have a survival rate of five years. However, when the disease is diagnosed early, before the onset of symptoms, it can be successfully treated and results in greater than 80% survival at five years.
Esophageal cancer arises from a precancerous condition known as Barrett's esophagus (BE). Currently, BE can only be diagnosed using an endoscope, but only 10% of patients who are eligible to undergo endoscopy take advantage of the screening opportunity. Their reluctance is likely due to the expensive and invasive nature of the procedure that also requires sedation.
Mayo Clinic gastroenterologist, Dr. Prasad Iyer, and his team have developed a new, minimally invasive method – using a compressed sponge on a string, about the size of a multivitamin capsule covered with a dissolvable shell – to diagnose Barrett's esophagus and associated cancer.
A patient undergoing the test swallows the capsule with a few sips of water. As the capsule dissolves it releases the sponge, which is then pulled out using the attached string. The whole procedure takes less than 10 minutes and can be administered by a nurse – the patient does not require sedation.
The sponge provides a rich sample of the entire esophagus – almost a million cells – which are then tested for biomarkers consistent with cancer or pre-cancer. "This test can make widespread screening for Barrett's esophagus feasible,” says Dr. Iyer.
Based on this analysis, researchers have developed promising genetic markers which can predict the presence/absence of BE with 97%–100% accuracy in Phase 1 and Phase 2 trials. They have also developed markers which detect the presence of dysplasia in these same samples. The study documenting the discovery and validation of novel methylated markers, along with results of a pilot study, have been published in the American Journal of Gastroenterology.
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