Oct. 12 (HealthDay News) -- British researchers say they've spotted key immune system proteins that could give doctors early warning of lung cancer.

A team at Nottingham City Hospital analyzed blood samples from 104 people with different types of lung cancer and 50 others who were cancer-free.

The samples were tested for autoantibodies -- immune system proteins that are directed at the body's own tissues in response to specific chemical signals. The researchers focused their search on a panel of seven autoantibodies associated with solid tumors. The autoantibodies are triggered when cancerous changes are taking place.

The team detected all seven autoantibodies, and very high levels of at least one of them, in almost 80 percent of the blood samples from the lung cancer patients. The autoantibodies were also found in eight out of the nine cancer patients whose cancer had not infiltrated the lymph nodes, indicating the cancer had not yet spread elsewhere, and the patients still had an 80 percent chance of being cured.

Only one healthy participant had more than one of the seven autoantibodies, the researchers reported Oct. 11 in the online edition of the journal Thorax.

Previous research suggests that these autoantibodies can be detected as early as five years before the clinical symptoms of cancer appear.

The researchers believe a blood test for the seven autoantibodies could be used for smokers and others at high risk for lung cancer. If there's a positive result, patients could be referred for further tests, such as CT or MRI scanning.

SOURCE: BMJ Specialist Journals, news release, Oct. 11, 2007