VIDEO: How to handle positive scans in lung cancer screening

WASHINGTON — David E. Midthun, professor of medicine and director of the lung cancer screening program at Mayo Clinic, discussed various aspects of lung cancer screening here at the annual American College of Physicians Internal Medicine Meeting.

"The other big concern within lung cancer screening is the issue of the positive scan, a scan that shows one or more lung nodules. I think you could define someone as normal, as someone who has not yet had a CT scan of the chest, in the sense that in this age group and smoking history, we're finding that over 50% have one or more lung nodules.”

The false positive rate within the National Lung Screening Trial was about 96%, with a positive report defined as a nodule 4 mm or larger , Midthun said. The important consideration is that a 4 mm nodule has less than 1% likelihood of being malignant, so false positive, in the usual sense of the word — indicating likely presence of malignancy — doesn't apply in the lung cancer screening setting.

In addition, to reduce harm and maximize benefit, the screening program has to handle the results and tell the patients what to do with the results, whether it be referral for a biopsy or annual scan, instead of just reporting the results to primary care physicians, he said.