An electronic device that “sniffs” breath may offer a new way to identify people with a condition that can lead to cancer of the oesophagus, researchers have revealed.
Recent figures suggest there are about 9,000 new cases of oesophageal cancer, or cancer of the food pipe, every year in the UK.
According to the charity Cancer Research UK, people diagnosed with Barrett’s oesophagus – a precancerous condition in which cells lining the food pipe change and may grow abnormally – have more than 11 times greater risk of getting a particular type of oesophageal cancer called oesophageal adenocarcinoma compared with the general population.
Barrett’s oesophagus often has no symptoms but is more common among those with long-term acid reflux problems, while being male, over the age of 50, and overweight or obese are among the other risk factors. UK figures suggest about 3% to 13% of people with Barrett’s oesophagus will go on to develop oesophageal adenocarcinoma, a type of cancer that is on the rise in western countries.
Currently, diagnosis of Barrett’s oesophagus relies on endoscopy – an expensive and invasive technique. Now researchers said they have developed an “electronic nose” that can distinguish between patients with and without Barrett’s oesophagus just by analysing their breath. The team said they hope the non-invasive approach could increase take-up of screening among those at risk of the condition – and hence reduce the number of cases of oesophageal cancer.
“If you have a test available that is non-invasive and easily [detects] patients at risk of developing oesophageal cancer, then of course the participation rates will be much higher as compared to using upper endoscopy,” said Prof Peter Siersema, co-author of the research from the Radboud Institute for Health Sciences in the Netherlands. “Taking this test takes only five minutes,” he added. Patients thought to have Barrett’s oesophagus could then be referred on for further investigation and treatment.
Writing in the journal Gut, Siersema and colleagues reported how they tested their device on 402 patients who were scheduled to undergo an endoscopy. Among these patients, 129 went on to be diagnosed with Barrett’s oesophagus, 141 had gastro-oesophageal reflux disease, and 132 had neither problem.
Before they underwent an endoscopy, each patient was asked to breath into an “electronic nose”– a device that can detect different volatile molecules.
In the breath, such molecules result from processes in the body, however while many of these occur in a healthy individual, some may be linked to particular diseases, either reflecting changes in cells or changes in the local community of microbes caused by a disease. As a result, a particular composition within a breath sample may act as a hallmark of a condition.
The team’s portable electronic nose incorporated a type of artificial intelligence to look for these patterns.
The team first trained the system on samples from 90% of the patients, allowing it to pick out patterns among the molecules in samples from those with and without Barrett’s oesophagus, before testing the system’s diagnostic prowess on the remaining 10% of samples. This was repeated 10 times.
Overall the results reveal that the nose correctly identified patients with Barrett’s oesophagus 91% of the time, while it correctly identified those without the condition 74% of the time. When the test was restricted to only those with either gastro-oesophageal reflux disease or Barrett’s oesophagus, the system was still able to distinguish patients, albeit less accurately.
Siersema said the team are now planning to repeat the work in a group of 1,000 patients, which he expects will increase the system’s accuracy. The team hope to subsequently test the device’s predictive powers in further groups, including in a primary care, or GP, setting.
Siersema said that if all went well the device might be available to GPs in two to three years.
Rebecca Fitzgerald, professor of cancer prevention at the MRC cancer unit at the University of Cambridge, who was not involved in the study, said the approach merited further research.
“It is interesting technology that tackles an important clinical problem – early detection of oesophageal cancer,” she said, although she noted the results suggested there would be a lot of false positives if the electronic nose was applied to a healthy population. “Further refinement and validation will be required but these initial data are encouraging,” she said.