NCRI lecture: Detecting oesophageal cancer with a ‘sponge on a string’

Oesophageal cancer is one of the fastest rising – and most deadly – cancers in the modern world. Rates in the UK alone have risen dramatically in the last thirty years, yet the five-year survival rates are among the poorest – partly because the disease is often detected at a late stage.

One of the main risk factors for the disease is a condition called Barrett’s oesophagus. This occurs in some people who suffer from what doctors call acid reflux, and the rest of us call heartburn.

Acid reflux is caused by stomach acid coming back up into the gullet. In Barrett’s oesophagus, this acid causes changes in the cells that line the oesophagus, increasing the likelihood that they will develop into cancer.

On average, one in ten of us gets heartburn at some point in our lives. But only one in ten people with heartburn has Barrett’s oesophagus. And around one in a hundred people with Barrett’s oesophagus will go on to get oesophageal cancer – a small risk, but still up to 125 times higher than the general population, and a similar degree of relative risk to women who carry faults in their BRCA genes.

So developing a way to identify these ‘high risk’ people, and offer them the appropriate monitoring and treatment, would save lives. Dr Rebecca Fitzgerald, from Cambridge University, is leading the way.

Sponge on a string

There are two obstacles to effectively screening for Barrett’s oesophagus. Firstly, the main method used to detect the disease – endoscopy – is uncomfortable and time-consuming. Secondly, there’s no agreed treatment for Barrett’s oesophagus that will prevent subsequent cancer from developing.

To overcome the first problem, Dr Fitzgerald’s team have developed a detection method that is elegant in its simplicity. It involves swallowing a pill on a string that expands in the stomach to form a rough sponge. This is then gently pulled up the oesophagus and out, removing a small sample of cells as it passes – you can see this in the videos below.

[youtube=http://uk.youtube.com/watch?v=-nf34PRmcpM]
[youtube=http://uk.youtube.com/watch?v=yaWA0Yfwvbw]

Although it looks pretty uncomfortable, patients who’ve undergone this proceedure and also experienced an endoscopy say they prefer the former by a large margin, according to Dr Fitzgerald’s research, which is funded by the MRC.

Her team has also worked out how to analyse the resulting cell samples to find tell-tale signs of Barrett’s oesophagus. This is no trivial matter, as the cells removed by the sponge include stomach, diaphragm and oesophageal cells, all jumbled together.

The researchers are also looking at ways of detecting dodgy cells using fluorescent markers, meaning that the screening process could potentially be automated in the future.

Dr Fitzgerald’s been running a trial – BEST – to look at how their ‘sponge-on-a-string’ performs alongside regular endoscopy. And the device has been approved for use by the MHRA – the organisation that regulates new medical devices in the UK.

But a screening test is no use unless there’s a decent follow up treatment. And scientists are making strides here too.

Radiofrequency ablation

Radiofrequency ablation, or RFA, is a relatively new method of treating disease. It involves inserting a probe into the body so that it’s in contact with the affected area, and heating it up, killing any cells in the immediate vicinity.

Researchers are currently conducting trials to look at whether treating Barrett’s oesophagus with RFA can stop the condition from coming back – effectively stopping it from developing into cancer.

If this turns out to be the case – and Dr Fitzgerald says the initial results are very encouraging – then screening people with long-term heartburn with the sponge-on-a-string, then treating any found to have Barrett’s oesophagus with RFA, could be a new way to prevent oesophageal cancer and reverse the upwards trend.

As well as RFA, researchers are also looking at drugs that could halt the transition from Barrett’s oesophagus to cancer. For example, there’s the Cancer Research UK-funded ASPECT and WASP trials, testing whether aspirin and anti-acid drugs can prevent the disease.

According to Dr Fitzgerald, there’s a fair amount of fine-tuning to be done to both the device and the RFA treatment, but if it all goes well, we could realistically expect to see some form of test being used to prevent cancer within the next five or six years.

 You can listen to Dr Fitzgerald talking about the importance of early detection for oesophageal cancer, and the sponge-on-a-string, in this podcast from the NCRI Conference.

Henry