Dutch researchers have found that men who screen negative for lung cancer are a bit less likely to try to quit smoking than men whose scan is inconclusive and requires follow up.

The findings in the European Respiratory Journal add to the debate over whether patients will perceive negative results in a lung cancer screen as a license to smoke or a chance to quit.

A U.S. study out last month suggested imaging the lungs of heavy smokers with a special type of CT scanner could catch cancers early and reduce individuals’ risk of dying from the disease by 20 percent compared to ordinary X-rays.

Caught early, lung cancer can be cured surgically, but it causes vague symptoms and usually is not diagnosed until it has spread. Globally, lung cancer kills 1.2 million people annually, and it will kill 157,000 people in the United States this year, according to the American Cancer Society.

Still, 300 smokers would have to be screened to save just one based on the U.S. study, and it is unclear if the scans, at about $300 each, will be cost-effective. The screens also come with a high rate of false alarms, raising questions about the risk to people who undergo unnecessary medical procedures as a result.

For the new study, Carlijn M. van der Aalst of Erasmus MC, University Medical Center Rotterdam, and colleagues tapped into data from an earlier trial on lung cancer screening.

That trial included a third test outcome, “indeterminate,” in addition to negative and positive for patients with small lumps in their lung that might be scars or tumors. Patients with such inconclusive results were referred to another CT scan a few months later.

At a two-year follow-up, the Dutch researchers found men who had tested inconclusive tried to quit more often than the group with negative results, with 1.9 attempts versus 1.5.

Nine percent of men in the negative-results group reported prolonged abstinence, compared to 12 percent among men with inconclusive results. The difference was not statistically reliable, though, and might have been due to chance.

However, the researchers found some hints that the more inconclusive test results a man had gotten, the more likely he was to be smoke-free.

Prolonged abstinence climbed from 11 percent of men after one indeterminate test, to 16 percent after two or more inconclusive results. The researchers said this increase might reflect a teachable moment to encourage smokers to quit.

“More research is needed to investigate the opportunities of lung cancer screening in current as well as former smokers to promote health risk-reducing behavior change and to prevent relapses and to investigate what the most cost-effective approach is in this screening population,” they write.

SOURCE: European Respiratory Journal, online December 9, 2010.