A clinical trial (called the Pan-Cancer Early Detection Study) is underway to look at breath tests and see if they can inform on whether someone has cancer. The team of researchers from Addenbrooke’s Hospital (Cambridge, UK) is looking to compare breath samples (also called breath biopsies) from a total of 1500 individuals, including healthy volunteers and those from people with a suspected or confirmed cancer diagnosis, to see if they can pick up differences that could be linked to the presence of early stage disease.
But what is the science behind? Well it is all to do with the fact that tumours by their very nature process metabolites and nutrients in a different way to normal cells and in doing so they produce by-products (or metabolites, in this case volatile organic compounds (VOCs)) that get into the bloodstream and end up in the air that we breath out through the lungs. By analysing breath samples collected from individuals after breathing into a facial mask for about 10 minutes, scientists will be seeking to analyse the VOCs present in each individual and see if they can identify trends or signatures associated with early cancer.
The test could potentially enable early detection of cancer before other signs are visible which makes a huge difference in terms of how curable the disease is. It is also a convenient, patient-friendly, quick and relatively inexpensive way of detecting cancer.
But this method has one caveat and that is the potential for misdiagnosis; for this to be a reliable approach with tangible impact on patient care, the test needs to have very good sensitivity for tumour detection, so no tumours are missed, and a high degree of accuracy, to avoid falsely diagnosing patients with cancer when no tumour is present. It is also unclear if other health conditions will also impact on the test results and whether the test is able to distinguish between different types of cancer (e.g. stomach compared to bladder cancer).
In any case, it is unlikely that the breath test alone will be able to provide a definitive cancer diagnosis, as is the case for urine and blood tests, but it could potentially provide a useful tool for assessing an individual’s health as part of a screening programme and following up with further examinations if necessary.
The results of the trial, which is supported by the charity Cancer Research UK and the breathalyser makers Owlstone Medical Ltd, are expected in 2021.
Clinical trial reference number: NCT03756597
