Lung cancer is the third most common cancer but it has a very high mortality rate. Less than 9% of patients survive more than five year after diagnosis - often because it is spotted too late.
A trial of 12,209 high-risk patients in Scotland found that those who took the blood test were diagnosed at an earlier stage than those who received standard care.
Oncimmune Holdings, the global company that designed the test, said it works by detecting autoantibodies made by the body's immune system as a natural defence against cancer cells.
In a statement, it said: "Lung cancer was chosen as the first target of the technology because it is the world's leading cause of cancer-related death and is often detected at an advanced stage with approximately 85% of patients in the UK undiagnosed until the disease has spread to other parts of the body."
The trial was reported earlier this year but the results are being presented at a conference in Barcelona.
Oncimmune said that, of those who had the EarlyCDT Lung test and developed lung cancer within two years, 41.1% were diagnosed at an early stage.