A potentially life-saving blood test has been developed that may allow doctors to spot signs of lung cancer up to five years before the disease shows up on traditional scans.
Early results from a major trial showed how antibodies produced by the immune system in response to lung cancer could be used as a diagnostic tool.
Of around 6,000 high-risk patients screened, about one in 10 tested positive for the antibodies.
From this group, 207 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.
The Scottish study recruited 12,000 adults aged 50 to 75 who were at high risk of lung cancer after smoking heavily 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.
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.
"Heavy smokers are particularly at risk, but it is just not possible to scan everyone who is considered high risk. And within those who are scanned, a CT scan alone can falsely suggest lung cancer or pick up incidental, non-clinically relevant findings, causing unnecessary worry and expense.
"We therefore need to find a way to identify which of the people at high-risk need a scan and a way to detect lung cancer before patients present with symptoms.
"This test allows us to scan from a much more informed position and removes the stress around many patients unnecessarily having to go through a CT scan. But most importantly, we feel it may help us to detect lung cancer in its earliest stages when we have an improved chance of successful treatment."
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.
Results from the research were presented at the British Thoracic Society (BTS) Winter Meeting in London.
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 - Britain's biggest cancer killer.
Dr Paul Beckett, consultant lung specialist at Derby Teaching Hospitals NHS Trust and British Thoracic Society member, said: "The good news is that we're seeing an increase in the volume of surgery being undertaken for lung cancer, with very strong success rates."