An experimental breath test can identify oesophageal and stomach cancers in people who already have cancer, according to a new study.

The results, published in JAMA Oncology, suggest the test can move to the next stage of development, to see if it can accurately diagnose these cancers in people who don’t know they have the disease.

Breath samples were collected from 335 people.

72 had stomach cancer, 55 had oesophageal cancer and 36 had cancer at the point where their oesophagus joins their stomach.

Their breath samples were compared to samples from 172 people without cancer but who had other stomach conditions.

The test correctly identified cancer in 81 out of 100 samples.

A patient’s breathes into a sealed bag.

The breath is then analysed by a machine called a mass spectrometer (link is external).

Mass spectrometers are very accurate molecular weighing scales that can identify what molecules are present in a sample.

This type of machine is specially designed to analyse molecules released by cells into the air we breathe out.

A computer programme analyses the reading from the machine and picks out certain molecules that are specific to these cancer types.

Professor Rebecca Fitzgerald, a Cancer Research UK expert on early cancer detection, said the results were promising, but the breath test still has a long way to go before it can reach patients.

“This study is interesting and matters to patients because breath testing could be easily carried out by a nurse or GP,” she said.

Around 9,200 new cases of oesophageal cancer are diagnosed in the UK each year, along with around 6,700 new cases of stomach cancer.

Diagnosing oesophageal and stomach cancers can be tricky as their symptoms are often the same as other conditions.

If a patient is suspected to have one of these two cancers they are scheduled for an endoscopy, which is invasive for the patient and expensive for health services.

If the breath test were to be introduced to the clinic it has the potential to cut costs and reduce the need for certain patients to have further tests, according to the Imperial College London team behind the breath test.

Professor George Hanna, lead author of the study at Imperial College London, said gastric and oesophageal cancers are mostly diagnosed a late stage when curative treatment might not be possible.

“Our breath test could be used as a first-line test before invasive investigations,” he said.

“Early detection of cancer gives patients more treatment options and save more lives.”

Researchers are also working on other tests that could help, including Fitzgerald’s team in Cambridge that is developing a ‘sponge on a string’ to sample cells from the oesophagus.

Fitzgerald said the researchers now need to make sure the breath test can be used to diagnose cancer instead of just recognising it in those who are already have it.

“It will be important to see how the computer programme behind the test performs in patients with upper gastro-intestinal symptoms to see if it can help doctors work out if they have cancer.”

Source: Cancer Research UK