Extensive, invasive testing is the last thing you want to go through when you’re worried about your health.

So the news that clinical trials to create breath-based diagnostic tools for cancer are in their final stages will be welcome to many.

The process, which would involve a patient simply breathing into a bag, could help to detect early stages of oesophagus, stomach, pancreas, colon, and even liver cancers.

Professor George Hanna of Imperial College London told The Observer that “these tumours formed more than 20% of all cancer cases in the world.”

The process so far has involved subjects “breath(ing) into the test for 10 minutes to collect a sample, which will then be processed.”

“Initially, I thought I might feel a bit claustrophobic wearing the mask, but I didn’t at all,” says patient Rebecca Coldrick.

After getting the sample, researchers will look for something called volatile organic compounds (VOCs).

“When cells carry out biochemical reactions as part of their metabolism they produce a range of VOCs,” says Cancer Research UK.

These can be exhaled from the body – hence the breathing test.

“If their metabolism becomes altered, such as in cancer and various other conditions, cells can release a different pattern of VOCs. The researchers aim to identify these patterns using Owlstone Medical’s Breath Biopsy® technology.”

If signs of cancer are found, the patient will then be sent on for further tests and screenings.

There are a few reasons why breathing tests could help to spot certain cancers early on.

“It is easier to treat cancer that is diagnosed early. This is because it might be smaller and won’t have spread to other parts of the body. But finding some types of cancer early isn’t easy as there are very few symptoms,” says Cancer Research UK.

For hard-to-spot and early-stage cancers, Cancer Research says a breath test could prove useful.

For instance, “Monitoring patients to find those at high risk of developing a cancer, like oesophageal, is very intrusive for patients, who may not even develop the disease.”

“A non-invasive test using this technology could help to further differentiate those likely to develop oesophageal cancer from those less likely to develop the disease,” Cancer Research add.

Billy Boyle, co-founder and CEO at Owlstone Medical, says that the breath-based screening could help to prevent further stress from more invasive testing, too – “The concept of providing a whole-body snapshot in a completely non-invasive way is very powerful and could reduce harm by sparing patients from more invasive tests that they don’t need.“

And The Observer says that “breath tests will give very quick answers. As the system is likely to be automated, it will also be relatively inexpensive.”

Prof George Hanna of Imperial College London told The Observer that researchers “have been working on this technique for more than 15 years and have now reached the stage where we are going through final clinical trials.”

“After that, we will need to get regulatory approval. So I anticipate that it will take another five years or so before we get cancer breath tests up and running in GP surgeries,” he says.

“if you think about it, it is a logical aim,” he adds. “Dogs can smell cancers in humans. In addition, we have breathalysers that can detect chemicals in the breath. So creating cancer breath tests was an inevitable goal.”

If you want to see the tests in action, Hanna is “planning to give public demonstrations of cancer breath-test technology at the Great Exhibition Road festival which will be held in London on 17-18 June” – though this will only be a demonstration, and will not actually test for cancer.