Breath test could save lives by detecting cancers of the stomach and oesophagus earlier
A study carried out by researchers from Imperial College London and the Karolinska Institutet in Sweden found that four out of five tested chemicals were expressed differently in the breath samples from those diagnosed with cancer, compared to those where no cancer had been found.
The breath test was able to correctly indicate cancer in around 85% of patients who had cancer, and similarly able to correctly exclude cancer in around 80% who did not have cancer.
The lead researcher, Dr Markar, said: “Because cancer cells are different to healthy ones, they produce a different mixture of chemicals. This study suggests that we may be able detect these differences and use a breath test to indicate which patients are likely to have cancer of the oesophagus and stomach, and which do not.”
Based on these findings, the chemicals of interest in the breath samples were:
- butyric acid
- pentanoic acid
- hexanoic acid
These five substances were considered a “chemical signature” for oesophageal cancer.
In most of those people with cancer who took part in the research, the cancer had spread to the lymph nodes. Therefore, it is unclear if the breath test would be able to detect less advanced cases.
Both oesophageal and stomach cancer tend to be diagnosed late because in the early stages they either cause no symptoms – in the case of oesophageal cancer – or symptoms that are vague and easy to mistake for other less serious conditions – in the case of stomach cancer.
Worldwide, oesophageal cancers account for around 1.4 million diagnoses a year but diagnosis tends to be late and therefore survival rates are low.
Routinely, these cancers can only be diagnosed using endoscopy, which involves a camera attached to a flexible tube being passed down the throat. The procedure can be uncomfortable and is costly to the NHS.
While the results show promise, it is not yet possible to say whether the test could have a future role in practice as it is unclear if the breath test would be able to detect cancers at an earlier stage. However, the test is likely to be most useful as a possible indicator for when endoscopy, a more invasive test, is needed in people who present with gastrointestinal symptoms.
Lorelle Williams, Assistant Litigation Executive at Fletchers said: “Whilst the issue of false negatives with this form of testing must be very carefully considered and safeguarding put in place, this breath test could be the first line of investigation, potentially saving some of the approximate 15,000 patients that are diagnosed with these cancers at least one endoscopy that costs the NHS around £600 per patient. Up to 95% of endoscopies for these types of cancer are returned as negative. The test’s accuracy is to be refined further with a much larger trial involving GPs to assess the effectiveness in detecting earlier symptoms and its ability to pick up other cancers such as pancreatic malignancies”.