June 29, 2011 -- Screening smokers and former smokers for lung cancer with low-dose CT imaging saves lives, a huge, decade-long study shows, but experts say it is too soon to recommend screening for everyone at risk.
Heavy smokers and former smokers who had the CT imaging were 20% less likely to die of lung cancer than smokers who got traditional chest X-rays.
Results from the National Lung Screening Trial, which included more than 53,000 people, were reported Wednesday in the New England Journal of Medicine.
The study is the first to show that screening can reduce lung cancer mortality by finding tumors early. But many questions remain, including who should have the test and at what cost to the health care system.
"We now know that it is possible to reduce deaths from lung cancer with low-dose CT, and now we need to figure out what to do with this knowledge," Dartmouth Medical School professor of medicine Harold C. Sox, MD, tells WebMD. "There are about 94 million smokers or former smokers in the United States, and screening even a portion of them would be very expensive."
Lung cancer claims about 157,000 lives a year in the U.S., according to the National Cancer Institute, which sponsored the study together with the American College of Radiology Imaging Network.
Beginning in the summer of 2002, more than 53,000 heavy smokers and former heavy smokers between the ages of 55 and 74 were enrolled in the study at 33 sites across the country.
The participants were randomly assigned to receive three annual screenings with either low-dose spiral CT or standard chest X-ray.
A traditional X-ray produces a single image of the chest, while spiral CT involves multiple, three-dimensional images of the chest cavity.
Studies show standard X-ray screening to be somewhat effective for identifying lung cancers, but it has never been shown to reduce deaths from the disease.
During the screening phase of the trial, 39% of the low-dose CT participants and 16% of the standard X-ray group had at least one positive screening result; more than nine out of 10 positive tests in the first round of screening led to further diagnostic testing.