Scientists create 'cytosponge' to detect oesophageal cancer

It comprises a ‘cytosponge’ compressed inside a gelatin pill capsule on a string, which is swallowed and dissolved before the expanded sponge is pulled back up to retrieve a cell sample.

Persistent heartburn or indigestion, caused by stomach acid coming back up the gullet, is a major risk factor for cancer of the oesophagus. Over time, this can cause the cells lining the lower oesophagus to start to resemble those found in the small and large intestines, a condition known as Barrett’s oesophagus.

If the condition can be diagnosed before cancer develops, patients can be offered closer monitoring and treatment to help remove abnormal cells.

However, most patients with heartburn symptoms take medication without ever having an endoscopy, meaning cases of Barrett’s oesophagus often go undiagnosed.

At present, the condition can only be detected by endoscopy — a relatively expensive procedure that involves putting a camera down the throat to collect a sample of the cells for analysis under the microscope.

A team from Cambridge University, led by Dr Rebecca Fitzgerald, set about looking for cheaper and more comfortable solutions for patients, noting a steadily rising incidence of the condition in the UK.

‘I’ve been thinking about this for well more than 10 years and at first we thought about things that looked a bit like a bottle brush with a rigid deployer. We did make them with engineering, but we never actually put it down anywhere,’ Fitzgerald told The Engineer.

The researchers then turned their attention to various balloon- and sponge-type devices that were being used in other areas of medicine, and then modified them to be able to collect cells.

‘It’s a fine line actually. It’s got to be big enough so that it’s in contact with the oesophageal wall, but it mustn’t be so big that it will cause damage and be too uncomfortable.’

With the correct dimensions in place, the team then turned to materials scientists for the optimal surface.

‘We had to find something that was non-toxic obviously, with the right kind of abrasiveness to collect cells and the right kind of pore size. Some of the previous devices were more like a bathroom type of sponge — this is much more of a lattice work or honeycomb, so it traps cells on the outside of it as well as the inside.’

The device has just undergone a series of clinical trials where it was shown to have an accuracy comparable to that of endoscopy.

One key advantage of the current system is that it can be performed easily by GPs, who simply slip the sponge into a sample bag and send it on for molecular antibody testing. It could pave the way for a large-scale screening programme such as those in place for other cancers.

However, speaking to The Engineer, Fitzgerald cautioned that, while the clinical trials were successful, there were aspects of the device’s design that currently make it unsuitable for mass production and they will be working with industrial partners to find a solution.