A simple check of cells taken from inside the cheek can help give an early warning of lung cancer, a study says.
Lung cancer kills 30,000 in the UK each year
The test by Canadian cancer research firm Perceptronix accurately predicted early stage-one lung cancer in two-thirds of cases.
The findings were presented at the American College of Chest Physicians conference in Montreal.
But British cancer experts said more work was needed to ensure the tests were accurate enough.
Lung cancer kills more than 30,000 people each year in Britain.
It is often diagnosed late, but is considered treatable if caught early enough.
Researchers took samples by scraping the inner cheek with a spatula.
The buccal mucosa cells were then tested by the company based in Vancouver to examine subtle changes in cells.
More than 150 lung cancer patients were tested along with nearly 1,000 people deemed to be at high risk of the disease.
It proved to be accurate in detecting early stage lung cancer in 61% of cases.
The researchers said the test could be targeted at high-risk groups and was so simple it could be performed at GP surgeries and dental practices with samples collected by patients themselves.
But they said more research was needed to fully develop the test.
Lead researcher Dr Bojana Turic said: "We believe that early detection is the key to reducing lung cancer mortality and have focused our approach around detecting stage-one lung cancer.
"But there is still some way to go."
Professor Michael Seckl, a Cancer Research UK lung cancer expert, said: "This work, while interesting, is still very early.
"This test does not seem to have sufficient predictive value, as it stands, to be a robust screening tool for early lung cancer.
"However, with more work, it may get better so watch this space."