Lung cancer screening often yields false positives
Posted Apr 20 2010 9:06am
Imaging tests used to screen symptom-free people for lung cancer often find suspicious growths that turn out to not be cancer, according to a U.S. government study published Monday.
Researchers say the findings point to a significant downside of using the tests — chest X-rays or spiral CT scans — to try to detect lung cancer early.
In recent years, CT scans, in particular, have been promoted by some hospitals and advocacy groups for lung cancer screening, even though studies have not yet shown whether such screening saves lives.
“The most important thing right now is to try to figure out if this lowers death rates,” Dr. Jennifer M. Croswell, the lead researcher on the new study, told Reuters Health.
The current findings, she said, add “pieces to the puzzle” by estimating how likely a person is to have a false-positive result if he or she has repeat screening tests over time.
For the study, Croswell and her colleagues at the National Institutes of Health (NIH) followed nearly 3,200 smokers and former smokers who were randomly assigned to undergo either a chest X-ray or CT scan to detect potentially cancerous abnormalities. If the first result was normal, participants had another test one year later.
Overall, the study found, the chances of having a false-positive result — a suspicious lesion that turned out not to be cancer — were 21 percent after one CT scan, and 33 percent after two.