A potentially life-saving blood test has been developed that may allow doctors to identify signs of lung cancer up to five years before the disease shows up on traditional scans.
Early results show that antibodies produced by the immune system in response to lung cancer could be used as a diagnostic tool.
About one in 10 of around 6,000 high-risk patients screened tested positive for the antibodies, and 207 from this group were found to have lung nodules - lumps of tissue in the lungs that may be cancerous or benign.
So far, chest X-rays and CT (computed tomography) scans have confirmed 16 cases of lung cancer among the positive-testing patients, three quarters of which were at an early stage.
More research is needed to assess the test, but experts believe it has the potential to bring cancers to light that would otherwise remain hidden for years.
Each year, more than 46,000 people are diagnosed with lung cancer in the UK and in excess of 35,500 die from the disease.
Heavy smokers are particularly at risk.
Dr Stuart Schembri, from the University of Dundee, who co-led the research, said: "Lung cancer is a serious and life-threatening illness and our best hope for successful treatment is to detect it as early as possible."
He said he hoped the test would help to detect lung cancer "in its earliest stages when we have an improved chance of successful treatment".
The Scottish study recruited 12,000 adults aged 50 to 75 who were at high risk of lung cancer either because they had been heavy smokers for 20 years or more, or because of their family history.
Half were given the antibody blood test while the rest received standard forms of diagnosis and care.
The scientists are now monitoring the progress of the study participants over two years to see if the test can reduce the incidence of late-stage lung cancer.