Duke radiologist urges caution in using CT scans to screen for lung cancer

The National Lung Screening Trial compared standard chest X-rays with low-dose CT scans in detecting tumors. The trial was stopped early because the CT imaging caught tumors earlier and led to 20 percent fewer deaths.

In a study published recently in the Journal of the American Medical Association, Duke University radiologist Dr. Edward Patz investigated the National Lung Screening Trial's rate of over-diagnosis.

The problem, Patz said, is that the CT images don't reveal whether a tumor is aggressive and life-threatening. Yet, patients would still incur the costs, anxiety and possible medical complications from a CT scan.

"There is a 20 percent chance that their tumor may be relatively slow-growing and may not cause them any harm," he said. "(Tumors) look virtually identical on (a) CT, but they are very, very different biological behaviors.

"Even once we have the tissue sample, we still cannot separate those who do well versus those who don't do well," he added.

If a tumor is seen on the low-dose CT scan, doctors could order a PET scan, which could help differentiate between patients who need surgery to remove their tumors and those who should wait.

Patz said his findings shouldn't change CT lung screening recommendations for older adults with a history of heavy smoking.

"This just provides them with the information so they can make a better informed decision of how to proceed," he said.