The National Cancer Institute says a special type of CT scan can detect lung cancer early enough to save some lives. It's the first evidence that a screening test may help fight the nation's top cancer killer.

At issue are controversial spiral CT scans, where a rotating
scanner views the lungs at various angles to spot growths when
they're about half the size that a standard chest X-ray can detect.
Some previous studies have suggested that the earlier detection
helps, while other research concluded it may do more harm than good by spotting too many benign growths.

The massive National Lung Screening Trial enrolled 53,000
current or former smokers to try to settle the debate - and found
20 percent fewer deaths from lung cancer among those screened with spiral CTs than among those given chest X-rays.