‘Sponge on a string’ test will help pinpoint gullet cancer
Trials of a new weapon in the battle against cancer are to be launched across Britain next month. The cytosponge – a sponge on a string – is to be used to pinpoint individuals at risk of developing oesophageal cancer.
The aim is to tackle one of Britain’s most pernicious illnesses. Oesophageal cancer is often diagnosed late in its development when it is difficult to treat. It is the sixth most common cause of cancer deaths in the UK with only 15% of patients surviving five years after diagnosis and is more common in older people.
“The cytosponge should allow doctors to pinpoint patients in the early stages of the disease or who are at risk of subsequently developing cancer,” said Professor Rebecca Fitzgerald, of Cambridge University. “The treatment is less invasive and more effective when detected at an earlier stage and that should greatly improve survival rates.”
The oesophagus – or gullet – carries food from our mouths to our stomachs. Cancer is triggered when cells on its lining start to divide uncontrollably.
Crucially this cancer is more common among people who suffer from a related ailment known as Barrett’s oesophagus and which often develops in people who have heartburn, acid reflux or serious indigestion. The cytosponge has been developed to pinpoint Barrett’s simply and cheaply.
“At present, people suspected of having Barrett’s have to go to hospital for an endoscopic examination which requires sedation and takes time. The cytosponge can be administered in minutes by a nurse,” said Fitzgerald, leader of the cytosponge project which has been funded by Cancer Research UK.
The sponge – which is now made by the medical manufacturer Medtronic – is administered as a pill which is swallowed. In the stomach it expands into a small sponge which is pulled back up the gullet by the string it is attached to, collecting oesophagus cells on the way. These are then sent for analysis.
Most cases of Barrett’s do not progress to cancer but a small proportion do and Fitzgerald’s team has developed a test which pinpoints a protein, called TFF3 , which is found only in pre-cancerous cells. “These show up as brown stains on the slides we make from patients’ oesophagus cells,” said Fitzgerald, of the CRUK Cambridge Centre.
Pinpointing these cells is done by pathologists working in central laboratories but the work can be painstaking. “It’s like looking for a credit card on a football pitch,” said Dr Marcel Gehrung, co-founder and CEO of Cyted, the company delivering the diagnostic testing. “It can take a pathologist quite a lot time to pinpoint affected cells as a result.”
Gehrung’s team is implementing an AI programme that has greatly improved the speed at which pre-cancerous cells can be found. “Ironically we were helped by the Covid pandemic which brought a halt to most endoscopic tests in hospitals – the main method for spotting oesophageal cancer cases,” Gehrung added. “That led to considerable enthusiasm for finding alternatives and the cytosponge has fitted the bill nicely.”
Early trials suggest that the sponge is more than 10 times more effective at pinpointing Barrett’s oesophagus than past methods. Early cancer detection rates should thus improve considerably in coming years and bring corresponding improvements in survival rates. “That should help us reach our goal of seeing three-quarters of people surviving their cancer within the next 20 years,” said Michelle Mitchell, head of Cancer Research UK.
A demonstration of the potential of the cytosponge is provided by the story of Liz Chipchase, a retired researcher involved in an early trial of the device. “I had suffered from acid reflux for years and was asked by my GP if I wanted to take part in the trial,” she told the Observer.
Cells from her oesophagus – provided by the cytosponge that she swallowed – showed she not only had Barrett’s but was in the early stages of oesophageal cancer. The cancer was removed four years ago and Chipchase has remained in good health since then. “I thought I was OK before I had the test but I wasn’t,” she said. “However, I am fine now – thanks to the cytosponge.”