New clinical data presented at the European Cancer Congress has raised hopes of a breath test that can successfully detect cancers of the oesophagus and stomach, side-stepping the need for endoscopy, the traditional method of diagnosis.

The test measures levels of five chemicals in the breath (butyric, pentanoic and hexanoic acids, butanal, and decanal) that in earlier research were indicated to be at different levels in patients with such cancers.

Researchers collected breath samples from 335 people at St Mary's Hospital, Imperial College Healthcare NHS Trust, University College London Hospital, and the Royal Marsden Hospital, London, of which 163 had been diagnosed with stomach or oesophageal cancer and 172 were deemed cancer free. Levels of the five chemicals were then measured to determine whether they could indicate the presence of cancer.

According to the data, the test showed overall accuracy of 85 percent, with a sensitivity of 80 percent (identifying those with cancer) and a specificity of 81 percent (identifying those who didn't have the disease).

Dr Sheraz Markar, an NIHR Clinical Trials Fellow from Imperial College London, under the supervision of Professor George Hanna, reportedly told the Congress that a breath test "could be used as a non-invasive, first-line test to reduce the number of unnecessary endoscopies. In the longer term this could also mean earlier diagnosis and treatment, and better survival."

But he also said the findings "must be validated in a larger sample of patients before the test could be used in the clinic."

As such, the researchers are now planning to undertake a larger trial involving patients given an endoscopy but not yet diagnosed with cancer, assessing the test's ability to detect the disease in a group likely to contain only a small percentage of cases.

Stomach and oesophageal cancer account for around 1.4 million new cancer diagnoses each year worldwide, but the five-year survival rate for both is just 15 percent, highlighting the urgent need for earlier detection of these diseases.

The research was funded by the National Institute of Health Research (NIHR), and supported by the NIHR Diagnostic Evidence Co-operative London at Imperial College Healthcare NHS Trust.