X-Ray Screening Doesn't Prevent Lung Cancer Deaths: Study
Researchers found no reduction in mortality among those who got chest X-rays
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Wednesday, October 26, 2011
WEDNESDAY, Oct. 26 (HealthDay News) -- Using chest X-rays to screen for lung cancer doesn't prevent deaths from the disease, a new study finds."There really was no benefit of the screening," said study co-author Dr. Christine Berg, chief of the early detection research group at the division of cancer prevention at the U.S. National Cancer Institute. "We detected some of the cancers a little earlier than we would have, but not early enough or in large enough numbers to really have an impact on lung cancer mortality."
Experts noted that the results of the large randomized clinical trial should put an end to any lingering questions about whether X-rays are useful in lung cancer screening. Recent research has indicated that CT scans are more effective at spotting malignancies earlier.
The study involved more than 150,000 never smokers, former smokers and current smokers aged 55 to 74 taking part in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.
Half of the participants, including smokers and nonsmokers, underwent annual chest X-rays for three or four years between 1993 and 2001; half did not get screened.
During 13 years of follow-up, similar numbers of people in both groups were diagnosed with lung cancer -- 1,696 in the screened group and 1,620 who were not screened.
There were 1,213 lung cancer deaths in the screened group and 1,230 in the unscreened group. Those who were not screened were no more likely to die of lung cancer than those who underwent the annual X-rays, according to the study in the Nov. 2 issue of the Journal of the American Medical Association. The research was published early online and is scheduled to be presented Wednesday at the American College of Chest Physicians annual meeting, in Honolulu.
Lung cancer is the leading cause of cancer death in the United States and worldwide, according to background information in the study.
Starting in the 1950s and through the 1970s -- a time when there were both lots of American smokers and a growing understanding about the dangers of smoking -- there was great interest in using chest X-rays to screen for lung cancer, Berg explained.
Studies published in the 1980s showed chest X-rays weren't all that effective, but those studies had small numbers of participants and other flaws that left lingering questions that have been answered in a more definitive way in this new study, Berg said.
Other experts agreed. "The study shows that lung cancer screening with chest X-ray isn't very effective, and certainly not as effective as CT scans," said Robert Smith, director of cancer screening at the American Cancer Society. "This paper indicates that the long tradition of using a chest X-ray to screen for lung cancer is over."
Another study, published recently in the New England Journal of Medicine, found that using a newer technology cut the death rate by 20 percent compared to X-rays.
Helical CT, also called "spiral" CT scan, gives a more precise look at lung tissue. While an X-ray is a single image, portions of which can be blocked by the ribs, a spiral CT scan takes pictures of multiple layers of the lungs to create a three-dimensional image. Think of it like slicing a loaf of bread, with each image about 2.5 millimeters to 3 millimeters thick, Berg explained.
"Lung cancer screening with low-dose helical CT is the only technology that has ever been shown to lower lung cancer mortality," she said.
The downsides of CT scans are that they're more expensive, and they have many more false positives because they're so sensitive, she added.
While lung cancer caught early is more treatable than lung cancer caught later, one challenge with the disease is that many lung cancers are aggressive and difficult to treat, Berg noted. "It's only recently that the drug companies and researchers are beginning to find some drugs that work," she said.
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