NEW YORK (Reuters Health) – The risk of lung cancer is increased in patients with rheumatoid arthritis, even after taking into account the effects of established risk factors such as tobacco and asbestos exposure, according to a study with United States military veterans.

Using a Veterans Health Administration database, Dr. Ritu Khurana, at Temple University Hospital in Philadelphia, and fellow researchers obtained the medical records for approximately 480,000 patients treated between 1998 and 2004, including 7,280 diagnosed with lung cancer and 8,678 diagnosed with rheumatoid arthritis.

The rate of rheumatoid arthritis was 3.4 percent among lung cancer patients compared with 1.8 percent among patients without lung cancer, the investigators report in the Journal of Rheumatology. After considering the potential influence of age, gender, tobacco and asbestos exposure, they found rheumatoid arthritis patients had a 43 percent greater risk of lung cancer compared with the controls.

The association grew stronger with age, Khurana’s group reports.

In a related editorial, Dr. Henrik Kallberg, of Karolinska Institute in Stockholm, points out that “it is not clear… whether the increased risk of developing cancer is due to coexisting risk factors such as smoking, to rheumatoid arthritis disease itself, to rheumatoid arthritis treatment, or simply to earlier detection of cancer because of intense medical surveillance.”

SOURCE: Journal of Rheumatology, September 2008.