WASHINGTON: Damage to cells lining the mouth can predict similar damage in the lungs that eventually leads to lung cancer in smokers, US researchers reported.

They hope it may be possible to some day swab the mouths of smokers to predict who is developing lung cancer - saving painful and dangerous biopsies of the lung. The process may also lead to tests that will predict other cancers, said Dr Li Mao, an expert in head, neck and lung cancer at the University of Texas MD Anderson Cancer Center in Houston.

"Our study opens the door to enhancing our ability to predict who has higher probability of getting tobacco-related cancers," Mao said in a statement on Sunday. "Not only lung cancer, but pancreatic, bladder and head and neck cancers, which also are associated with tobacco use."

Smoking is the leading cause of lung cancer, but only about 10% of smokers ever get it. It causes few symptoms until it is advanced, which means patients are rarely diagnosed or treated until it is too late for a cure. Mao's team wanted to find a way to monitor patients taking a drug - the COX-2 inhibitor celecoxib, sold by Pfizer under the brand name Celebrex - in the hopes of preventing lung cancer