Patients with suspected lung cancer could in future be breathalysed to check if they have the disease.
Scientists have developed a sensor that can quickly detect lung cancer molecules on the breath.
They believe the technology could lead to cheap, portable breath-test devices with the potential to save large numbers of lives by spotting cancer early.
The lung cancer biomarkers were found by comparing breath samples from 40 diagnosed patients and 56 healthy individuals.
From the results, the researchers identified 42 "volatile organic compounds" (VOCs) present in the breath of 83 per cent of cancer patients but fewer than 83 per cent of healthy volunteers.
Four of the most reliable were used to develop a nine-sensor array made from tiny gold particles coated with reactive chemicals sensitive to the compounds.
Exposed to the VOCs, the sensors generated an electrical signal that produced a distinctive trace pattern.
In tests, the device easily distinguished simulated "healthy" and "cancerous" breath made from artificial compound mixtures.
The Israeli scientists led by Dr Hossam Haick from the Technion-Israel Institute of Technology in Haifa, outline the research today in the journal Nature Nanotechnology. They wrote: "Our results show great promise for fast, easy and cost-effective diagnosis and screening of lung cancer.
"The developed devices are expected to be relatively inexpensive, portable, and amenable to use in widespread screening, making them potentially valuable in saving millions of lives every year."