Portable ‘electronic nose’ picks up early warning signs of oesophageal cancer
Author: Caroline White
A portable ‘electronic nose’ can accurately pick up the changes that precede the development of oesophageal cancer, indicates a proof of principle study*, published online today in the journal Gut.
This inexpensive and non-invasive technique may prove a promising test for diagnosing Barret’s oesophagus in primary care, without the need for costly and uncomfortable endoscopy, suggest the researchers.
The number of new cases of oesophageal cancer has risen six-fold over the past few decades, with most cases diagnosed when the disease is already advanced and very difficult to treat successfully.
Barrett’s oesophagus, a condition in which healthy cells lining the food pipe are replaced by abnormal cells, is a known precursor to the disease.
The current procedure for diagnosis is expensive, and unpleasant for patients, making it unsuitable for population screening.
This has prompted scientists to explore less invasive and cheaper alternatives, including analysis of volatile organic compounds, or VOCs for short.
VOCs, the gaseous compounds produced by metabolic processes in the body, including inflammation and abnormal cellular activity, can be detected in a person’s breath.
The researchers wanted to see how effective and accurate a portable ‘electronic nose’ would be for picking up Barrett’s oesophagus.
Some 402 adults scheduled for endoscopy breathed into a highly sensitive electronic nose, designed to detect subtle differences in VOC patterns, for five minutes.
Of this group, 129 patients had Barrett’s oesophagus; 141 had acid reflux disease, including 50 who had an inflamed oesophagus as a result; and 132 had a normal oesophagus or hiatus hernia that accounted for their symptoms.
Analysis of the VOC profiles detected by the 'electronic nose' showed that these differed significantly among patients with Barrett’s oesophagus, acid reflux, and those with a normal oesophagus/hernia.
The sensitivity of the device was 91%, while the specificity was 74%.
When the analysis was further restricted to patients who had been taking proton pump inhibitors to curb stomach acid production for at least a month or those with a hiatus hernia, both of which are likely to muddy the diagnostic waters, its accuracy was still good.
“The findings of our study provide evidence that patients with [Barrett’s oesophagus] have VOC breath prints different from those without,” write the researchers.
The sensitivity of the device was 91%, while the specificity was 74%. It’s still not clear exactly how breath VOCs indicate cancerous cell changes, but the sensitivity and specificity of VOC breath testing for Barrett’s oesophagus is comparable to that of breast cancer and bowel cancer screening, they explain.
Chemical analytical techniques for VOC analysis are very effective, but they are also expensive. What’s more, they are time consuming and require highly skilled staff to operate them and analyse the results, point out the researchers.
Further research will be required to validate these findings in a much larger study, they emphasise. But they conclude: “Given the high tolerability, high acceptability and low costs, breath testing may be a promising approach to be used for non-invasive screening for [Barrett’s oesophagus] in a primary care setting.”
*Peters Y, Schrauwen RWM, Tan AC, et al. Detection of Barrett’s oesophagus through exhaled breath using an electronic nose device. Gut Published Online First: 25 February 2020. doi: 10.1136/gutjnl-2019-320273