The use of computed tomography, or CT, scans as a screening tool for lung cancer showed fewer people died compared to those screened with a chest X-ray, according to the results of a large-scale study released Thursday.

The study, funded by the National Cancer Institute, showed that 20 percent fewer people died of lung cancer among those who were given CT scans compared to a standard chest X-ray.

The study marks the first time a clear benefit has been shown for the use of a lung-cancer screening test. Unlike for colon cancer and breast cancer, regular screening isn't common for lung cancer, which is the leading cause of all cancer deaths in the U.S.

Until now, no study had clearly shown that screening for lung cancer would reduce the death rate, as opposed to simply finding deadly tumors earlier.

The study, known as the National Lung Screening Trial, involved more than 53,000 current and former heavy smokers ages 55 to 74, and was designed to compare two screening procedures for lung cancer—low-dose helical computed tomography and a chest X-ray.

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