CHICAGO - Routine chest X-rays do not prevent lung cancer deaths, not even in smokers or former smokers, according to a big U.S. government study challenging a once common type of screening.
In the study of more than 150,000 older Americans, those who had four annual chest X-ray screenings were just as likely to die of lung cancer as participants who didn't have those tests.
The results from the National Cancer Institute-funded research confirm previous, smaller X-ray studies. They follow another big study from that institute favouring a newer, more sophisticated imaging test. That found fewer lung cancer deaths among current or former heavy smokers who had special CT imaging scans versus those who had chest X-rays.
CT scans provide much more detailed images than X-rays, and while no major medical group recommends any type of routine lung cancer screening, several are preparing new guidelines.
Screening refers to routine tests in people without symptoms; doctors say chest X-rays are still useful to help diagnose people with lung cancer symptoms, including a persistent cough or coughing up blood.
Chest X-ray screening for lung cancer was common decades ago, and some doctors continue to recommend it in smokers and former smokers. The new study results should put an end to that practice, said Robert Smith, director of cancer screening at the American Cancer Society.
"No one recommends it but they do occur quite a lot," said Smith, who was not involved in the study.
The study was released online in the Journal of the American Medical Association on Wednesday, when it was presented at an American College of Chest Physicians meeting in Hawaii. The doctors' group is among those preparing new lung cancer screening recommendations.
The study's participants were aged 55 to 74 and were tracked for about 13 years. During that time, there were about 1,200 lung cancer deaths in participants who got X-rays and in those who got usual medical care. That's equal to about 14 deaths per 10,000 people each year.
Lung cancer is the leading cancer killer; it will be diagnosed this year in about 220,000 people nationwide, and more than half that number will die from lung cancer, the cancer society estimates.
Less than one per cent of never smokers will develop lung cancer in their lifetime. By contrast, about 18 per cent of current smokers will get the disease by age 75; the risk is somewhat lower but not zero for former smokers, depending on how long ago they quit, said Dr. Christine Berg, the study's senior author and chief of the National Cancer Institute's early detection research group.
"We were really hoping chest X-rays might be beneficial," partly because they are relatively inexpensive -- about $60 versus hundreds and sometimes thousands of dollars for CT scans, Berg said.
But Smith said the study shows routine chest X-ray screenings in healthy people without symptoms are "a waste of time," plus they can lead to false-positive results that may lead to invasive and potentially harmful tests.
Similar concerns have been raised recently about too-frequent pap tests for cervical cancer, routine PSA tests for prostate cancer screening, and excessive mammograms for breast cancer, leading to revised guidelines from the U.S. Preventive Services Task Force.
That independent group, which advises the U.S. government, concluded in 2004 that there was no evidence to support any method of routine lung cancer screening in people without symptoms, including X-rays and CT scans.
It is updating those guidelines based on recent new evidence, including last year's CT scan vs. chest X-ray study, and will take into account the new X-ray study, too, said Dr. Michael LeFevre, co-vice chairman of the task force and a family physician at the University of Missouri. That process may take up to two years, he said.
Because CT scans also can yield false positive results, it is unlikely any group will recommend them for screening nonsmokers.
