For the first time, a large study shows that using CT scans to screen smokers and ex-smokers for lung cancer can reduce lung cancer deaths by 20% -- potentially saving thousands of lives -- by catching lethal tumors at an earlier, more treatable stage.
Nearly 160,000 Americans a year die from lung cancer, the leading cause of cancer deaths in the world, the American Cancer Society says.
In addition to reducing deaths from lung cancer, the screenings also reduced deaths from any cause by 7%, according to the National Cancer Institute, which financed the eight-year, $250 million study of 53,000 people ages 55 to 74.
Until now, there has never been a reliable way to catch lung cancers early.
Researchers randomly assigned half the patients to receive three annual screenings with either a chest X-ray or low-dose CT (computer tomography). Everyone in the study was a smoker or a former smoker who smoked the equivalent of a pack a day for 30 years.
The results, which were released Thursday, suggest that CT lung screenings are about as effective as mammograms, says Bruce Johnson of Boston's Dana-Farber Cancer Institute, who was not involved in the study.
"It's one of those red-letter days that everyone will remember for a long time," says David Brenner, a professor at Columbia University in New York, who also was not involved with the study.
Doctors expect many of the nation's nearly 100 million smokers and ex-smokers to ask for scans. Any hospital can perform them, Johnson says.
Experts note that avoiding tobacco -- which causes 87% of lung cancers -- is still the best way to prevent smoking-related illness, which kills more than 400,000 Americans a year.
Researchers say they don't know whether CT screenings help non-smokers or people younger than 55. Cancer institute director Harold Varmus says his agency isn't making any recommendations. The American Cancer Society will consider the results but also hasn't yet changed its recommendations, says chief medical officer Otis Brawley.
Right now, neither Medicare nor private insurance companies pay for lung cancer screenings with CT scans, Varmus says. He notes that the Medicare program is going to examine the study's results to decide on coverage.
In general, CT screenings cost about $300, Varmus says. But screening CTs have other costs, such as the risk that patients will have to endure unnecessary invasive follow-up tests. About 25% of patients in the study needed some kind of follow-up, Varmus says. Annual CT screening also increases the risk of new, radiation-related cancers.
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