Landmark Lung Cancer Screening Study
Compares Screening Procedures
The largest lung cancer study ever to be conducted in the United States has yielded its final findings, revealing that screening current or former heavy smokers with a CT scan can reduce deaths from lung cancers by 20 percent. Georgetown Lombardi Comprehensive was one of 33 centers around the country that participated in the study, and the only site in the Washington, D.C. area.
The National Lung Screening Trial, or NLST, involved more than 53,000 current and former heavy smokers ages 55 to 74. Under Georgetown Lombardi’s leadership, 1,800 men and women were recruited into the clinical trial at Georgetown Lombardi as well as two other Georgetown University Hospital community-screening locations.
The study compared the effects of two screening procedures for lung cancer: low-dose helical computed tomography (CT) and standard chest X-ray. It also examined complications from follow up procedures after a positive result. The eight-year-long study, the results of which were published in June in the New England Journal of Medicine, determined that the screening does carry risk, though not common.
“These results are significant. It is clear from this study that CT screening of smokers or former smokers at high risk of developing lung cancer can save lives,” says Claudine Isaacs, MD, lead investigator of the NLST study at Georgetown Lombardi. “That said, with the newly published results, we’re getting a look at the false-positive rate and the complications that can come with follow-up procedures to positives scans. This is important information when weighing the risks and benefits of screening.”
False-positive results describe scans that show a lesion or artifact in the lung that, after a follow up CT scan or invasive procedure (such as a biopsy), are determined to not be lung cancer.
“We are grateful to all the men and women who participated in this important study. Clinical trials are critical to making progress in medicine,” Isaacs says.
“Going forward, we need to determine who best benefits from this screening and ensure that we are offering those at risk the best course of screening,” says Louis M. Weiner, MD, director of Georgetown Lombardi. “While studies like these generate excitement, clearly there is much more work to be done. Georgetown Lombardi and our MedStar partner hospitals continue to explore effective ways to reduce lung cancer deaths including prevention and screening efforts, and by conducting clinical trials with the newest diagnostic tools and available cancer fighting drugs.”
A Closer Look at the NLST
The NLST study began enrolling participants in August 2002. Participants were required to have a smoking history of at least 30 pack-years and were either current or former smokers without signs, symptoms, or history of lung cancer. Pack-years are calculated by multiplying the average number of packs of cigarettes smoked per day by the number of years a person has smoked.
The men and women were randomly assigned to receive three annual screens with either low-dose helical CT (often referred to as spiral CT) or standard chest X-ray. Helical CT uses X-rays to obtain a multiple-image scan of the entire chest during a 7 to 15 second breath-hold. A standard chest X-ray requires only a sub-second breath-hold but produces a single image of the whole chest in which anatomic structures overlie one another. Previous efforts to demonstrate that standard chest X-ray examinations can reduce lung cancer mortality have been unsuccessful.
The trial participants received their screening tests at the time of enrollment and at the end of their first and second years on the trial. The participants were then followed for up to another five years; all deaths were documented, with special attention given to the verification of lung cancer as a cause of death. A total of 356 deaths from lung cancer had occurred among participants in the CT arm of the study, whereas a significantly larger 443 lung cancer deaths had occurred among those in the chest X-ray group. This represents a 20 percent reduction in lung cancer mortality offered by CT scans compared to the X-ray group.