Key points from article :
Experts carried out a random controlled trial on more than 12,000 people in Scotland.
Adults who were smokers or former smokers took part in the trial.
People who took the test were more likely to be diagnosed with cancer at an early stage.
Findings were presented at the 2019 World Conference on Lung Cancer.
Experts hope the test will be given to another 200,000 patients for further research.