Often, the abnormalities turned out to be lymph nodes or scarring from past infections.
"As this study demonstrates, the rate of findings suspicious for lung cancer was high in each screening round (over 27 percent in the first two rounds), but low-dose CT exams also can identify other non-lung related abnormalities, and this positivity rate also was high," Brawley said. "So managing abnormal findings and avoiding doing harm in individuals with false-positive findings are among the major challenges we will confront."
And sticking a needle deep into the tissue of the lung for a biopsy is an invasive procedure that has its own set of risks, such as a collapsed lung, Bevers said.
The trial also found that about 1 percent of people who underwent surgery to remove a cancerous tumor died. Nationwide, that number is closer to 4 percent, which may erase some of the life-saving gains from the early detection, Sox said.
The American Cancer Society has not yet issued recommendations on who should be screened for lung cancer using a CT scan, although this study, as well as other ongoing and soon-to-be published studies out of Europe, will be taken into consideration, Brawley said.
"Guidelines groups have yet to carefully evaluate these and other data to determine who should and should not consider undergoing screening for early lung cancer detection and how often," he said.
Above all, if you smoke, quit, Brawley said. That, more than anything else, will help you avoid getting sick.
"We estimate that quitting smoking will in 10 years' time reduce a smoker's risk of death from lung cancer as much as CT screening did in this study," he said.
The U.S. National Cancer Institute has more on lung cancer.
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