Using CT scans to screen patients for lung cancer doesn't appear to save lives, according to a new study that says the annual screenings may miss the most deadly, fast-growing cancers.

The Associated Press reported that while a long-term study on the effectiveness of CT scans as screening tools for lung cancer is not yet complete, research published this week concluded that the scans could actually increase health risks for some patients. That's because the scans did increase diagnosis and treatment, but probably only detected slow-growing cancers that might never have caused death. Patients who underwent surgery for these cancers may not have had any net health benefit, and in fact put themselves at risk of surgical complications, the authors said.

"We don't see a trace of evidence that a single life was saved, that a single case of advanced cancer was avoided," said study co-author Dr. Peter Bach of Memorial Sloan-Kettering Cancer Center.

The American Cancer Society won't endorse the CT scans until evidence of their effectiveness is shown, and most insurers don't cover the $300-$400 screenings, either.

The study was published in the March 7, 2007 issue of the Journal of the American Medical Association.