Portable 'electronic nose' can accurately screen Barrett's oesophagus
A new Portable 'electronic nose' can accurately screen Barrett's oesophagus.
A
portable 'electronic nose' can accurately pick up the precursor
condition to food pipe (oesophageal) cancer, known as Barrett's
oesophagus, indicates a proof of principle study, published online in
the journal Gut. Researchers found that the accuracy of the electronic
nose was high, especially among patients taking a high-dose proton pump
inhibitor, an acid reduction medicine.
This
inexpensive and non-invasive technique may be a promising test for
diagnosing oesophageal cancer in primary care, say the researchers.
The
number of new cases of this cancer has risen sixfold over the past few
decades, with most cases being diagnosed when the disease is already
advanced and difficult to treat.
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.
It
can be diagnosed using a long flexible tube with a camera on the end
(endoscope). But the procedure is expensive and unpleasant for patients,
making it unsuitable for population screening.
So
scientists have been exploring other less invasive and cheaper options,
including analysis of volatile organic compounds, or VOCs for short.
VOCs
are gaseous compounds produced by metabolic processes in the body,
including inflammation and abnormal cellular activity, which can be
detected in a person's breath.
The
researchers wanted to see how effective and accurate a portable
'electronic nose' device 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 5 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%--in other words, its ability to pick
up Barrett's oesophagus--and its specificity was 74%--in other words,
its ability to detect those without the condition.
When
the analysis was further restricted to patients who had been taking
drugs (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," they
write.
While it's still
not clear exactly how breath VOCs indicate cancerous cell changes, 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 have also been used, and 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."