April 19 (HealthDay News) -- Someday, a simple urine test might spot smokers at highest risk for lung cancer, scientists report.
The research is still in its preliminary stages, and it may be years before such a test becomes publicly available. But if it works, the urine-based screen could give added motivation to smokers who can't find other reasons to quit, said study author Dr. Jian-Min Yuan, an associate professor at the University of Minnesota.
"You can focus on the higher-risk people, maybe have them come into smoking-cessation programs," Yuan said. "Hopefully, it can reduce the amount of tobacco that is consumed."
The findings were to be released Sunday at the American Association for Cancer Research's annual meeting in Denver.
The U.S. Centers for Disease Control and Prevention estimates that about 23 percent of adult Americans are smokers, and smokers account for about 87 percent of cases of lung cancer, the number one cancer killer.
Currently, there is no way to determine which smokers are most likely to develop lung cancer. Doctors do know that smokers with chronic obstructive pulmonary disease or a prior family history of lung cancer are at higher risk, said Dr. Norman Edelman, chief medical officer with the American Lung Association.
In the new study, researchers in Minnesota, Singapore and China examined findings from two prior surveys.
One study looked at more than 18,000 men who enrolled when they were aged 45-64 in Shanghai, China. The other study included more than 63,000 men and women of Chinese descent, aged 45-74, and was conducted in Singapore between 1993 and 1999.
In the new study, the researchers focused on 246 smokers who developed lung cancer and 245 smokers who were similar to them. The researchers examined urine samples from the subjects and tried to figure out if a biologic marker known as NNAL could predict cases of lung cancer.
The team found that the third of smokers who had the highest levels of NNAL and a marker called cotinine were 8.5 times more likely to develop lung cancer than those with levels in the lowest third and similar histories of smoking.
"We compared apples with apples -- people who smoked the same amount of cigarettes and for the same amount of years," Yuan noted.
Scientists could perfect the predictive powers of the test, which costs about $100 to $120, within a few years, Yuan said.
But there's a catch: Currently, no intervention -- outside of quitting smoking -- reduces a smoker's chance of developing lung cancer.
A screening test could help doctors figure out which smokers should undergo more sophisticated screening, Edelman said, but at the moment it's difficult to detect tumors in their early stages.
"We need better and more sophisticated strategies to allow us to screen for early lung cancer, as that is only when it is curable but also when there are no symptoms," he said.
SOURCES: Jian-Min Yuan, M.D., Ph.D., associate professor, University of Minnesota, Minneapolis; Norman H. Edelman, M.D., chief medical officer, American Lung Association, Chicago; April 19, 2009, presentation, American Association for Cancer Research annual meeting, Denver