Low-dose CT scans decrease lung cancer deaths by 20 percent
AURORA, Colo. – Screening for lung cancer using low-dose “spiral” CT scans reduces lung cancer mortality by 20 percent compared to screening with chest X-ray, the National Cancer Institute announced today.
“For the first time there is evidence from a randomized prospective clinical trial that low dose screening chest CT results in a decrease in the number of deaths in people at high risk for lung cancer,” said Kavita Garg, MD, professor of radiology at the University of Colorado School of Medicine [SOM] and University of Colorado Hospital. “We could save lives. It’s just a matter of time until we get official guidelines for how best to use this tool.”
The results come from the National Lung Screening Trial, a randomized national study involving more than 53,000 current and former heavy smokers ages 55 to 74. The NLST compared the effects to two screening procedures—low-dose helical computed tomography (CT) and standard chest X-ray—on lung cancer mortality and found 20 percent fewer lung cancer deaths among trial participants screened with low-dose CT. The study also showed a 7 percent overall decrease in death from all causes in those screened with CT.
The University of Colorado Cancer Center was the among the largest of 30 trial sites, enrolling 3,743 Colorado smokers and former smokers who had a 30-plus pack year history of smoking. Participants were randomly selected for three annual lung cancer screenings using chest X-ray or low-dose CT scan, then were followed for five years. Garg was co-principal investigator for the Colorado arm of the trial.
Guidelines are forthcoming for how often people at high risk of lung cancer should be screened using low-dose CT will come, the NCI said. Until the data is further analyzed, University of Colorado doctors are cautious, yet optimistic, about recommending screening for high-risk people.
“This is good news for people at high risk for lung cancer, specifically those who have smoked heavily,” said David Lynch, MBMD, professor of diagnostic radiology at the SOM and National Jewish Health. He serves on the national NLST executive committee.
Lynch and Garg recommended that people who have smoked heavily talk to their personal physicians about whether they should undergo screening with low-dose CT. Medicare, Medicaid and private insurance companies do not cover the cost of screening CT scans today.
NCI also announced preliminary data from the Prostate, Lung, Colorectal and Ovarian Cancer screening trial which looked at people enrolled in that study who met the NLST criteria and were either screened for lung cancer using chest X-ray or not screened at all.
“The data indicates that there is no benefit in screening for lung cancer with chest X-ray compared to not screening at all,” Lynch said. “That’s a significant finding, because when you combine it with the NLST data, it means CT screening for lung cancer saves lives compared to not screening at all. That’s never been shown before.”
Size matters in lung cancer
Lung cancer is rarely caught in early stages when it is more easily treated, said Garg, a member of UCCC’s Lung/Head & Neck Cancer Program.
“Size does matter here,” she said. “We stage lung tumors and determine how to treat them based on the size of the tumor, the number of lymph nodes involved and whether the cancer has spread. If we find small tumors that have not spread, we have a much better chance of curing the patient.”
About 50 percent of people diagnosed at UCCC with early-stage lung cancer are alive five years later, compared to less than 5 percent who are diagnosed with Stage IV lung cancer, according to the University of Colorado Hospital tumor registrar.
Risks of screening
Garg echoed cautions from the NCI that screening for lung cancer is not without risk.
“About 25 percent of participants who had CT scans had false-positive readings, meaning there was an abnormal finding that, upon further investigation, turned out not to be cancer,” she said. “That means unnecessary and invasive procedures like biopsies, additional radiation exposure and higher costs.”
She said radiation exposure from a low-dose spiral CT is slightly higher than that of a double-view mammogram, and about 100 times higher than chest X-ray.
Not a cure, does not diminish risks of developing lung cancer
One message is clear from Colorado doctors and the NCI: these results should not give people the idea that it’s OK to smoke.
“In the long run, our first area of discussion must start with smoking prevention and smoking cessation,” she said. “After that, we can now say people at high-risk should undergo screening. Lung cancer is a big public health issue, and if we can avoid late stage cancers, we can not only save lives, but we can save a lot of money. It’s very expensive to treat late-stage lunch cancer, and the treatment doesn’t save many lives at that point. This study leaves room for hope for many people.”
About the University of Colorado Cancer Center
The University of Colorado Cancer Center is the Rocky Mountain region’s only National Cancer Institute-designated comprehensive cancer center. NCI has given only 40 cancer centers this designation, deeming membership as “the best of the best.” Headquartered on the University of Colorado Denver Anschutz Medical Campus, UCCC is a consortium of three state universities (Colorado State University, University of Colorado at Boulder and University of Colorado Denver) and five institutions (The Children’s Hospital, Denver Health, Denver VA Medical Center, National Jewish Health and University of Colorado Hospital). Together, our 440+ members are working to ease the cancer burden through cancer care, research, education and prevention and control. Learn more at www.uccc.info.
Contact: Lynn Clark, 303-724-3160, [email protected]