Scientists have developed a test for early-stage lung cancer similar to the breathalyzers used to estimate blood alcohol content in motorists.

The test is the brainchild of scientists at the Max Planck Institute for Heart and Lung Research (MPI-HLR) in Bad Nauheim, Germany.

While not ready for the market just yet, it has shown promise in initial trials.

“The breath test could make detection of early-stage lung cancer easier and more reliable, but it won’t completely supplant conventional techniques,” says Guillermo Barreto, a working-group leader at MPI-HLR.

Certain molecules of RNA – a nucleic acid in all living cells whose main role is to carry the genetic code from DNA needed to synthesise proteins – are altered by cancer growth.

Scientists isolated the extremely low concentrations of RNA molecules released from lung tissue into exhaled breath, noted the RNA profile in subjects with and without lung cancer, and used the data to devise a model for diagnosing the disease.

In a trial involving 138 people whose health status was known, the breath test was able to identify 98% of those with lung cancer.

Barreto says another trial is planned on more than 2,000 patients in five lung clinics.

The scientists also aim to expand the number of tumour markers so that different types of lung cancer can be identified.

According to the latest statistics from the World Health Organization, cancer accounted for 8.8 million deaths in 2015.

Early-stage lung cancer, no symptoms

Lung cancer is the most deadly cancer of all, and killed an estimated 1.69 million people during the same period.

People with early-stage lung cancer usually have no symptoms. When clear symptoms appear, the disease is often too advanced to cure.

When a tumour is detected early, it’s almost always by chance. That’s why an early test for high-risk groups – primarily older smokers, but also people with a family history of the disease – would be a huge boon.

“If detection were possible at an early stage, as many as 70% of the patients could live another five years and more,” says the German Cancer Society (DKG).

Smoking is a known cause of lung cancer, still the biggest killer of all cancers. Photo: dpa

Excited by the potential

Dr Juergen Wolf, an expert on lung cancer diagnostics at Cologne University Hospital, describes the breath test as “super exciting” but cautions that “there’s still a long way to go before it’s usable”.

A breath test that works only in cases of advanced lung cancer “wouldn’t be so valuable”, he says, while one identifying patients with smaller tumours “would be great”.

In any event, he added, “the approach is worth pursuing”.

Regular cancer screening using low-dose computed tomography scans – similar to mammograms for breast cancer – is controversial in some countries.

They’re recommended for smokers over 50 years of age in the US, but not in Germany, for example.

The DKG points to a high number of false positive diagnoses.

More early detection research

Research is also underway on other methods to detect lung cancer early. “A lot is happening at the moment,” Wolf says.

Blood tests have been promising, he says, but analysis of sputum – matter expectorated from the respiratory system – has proven to be useless and “can be shelved”.

It’s still preferable to not get the disease in the first place, of course. And the prime preventative measure – recommended by the DKG, Wolf and countless other experts – is: “Don’t smoke.” – dpa