A large national US study finds that screening current or former heavy smokers with a CT scan can reduce deaths from lung cancers by 20 percent. One potential reason for the reduction is that the scan can pick up tumors at an early stage.
The study was conducted by the National Cancer Institute at 33 centers around the country including Georgetown Lombardi Comprehensive Cancer Center, a part of Georgetown University Medical Center.
The National Lung Screening Trial (NLST) involved more than 53,000 current and former heavy smokers ages 55 to 74. More than 1,800 men and women participated through Lombardi. The study compared the effects of two screening procedures for lung cancer -- low-dose helical computed tomography (CT) and standard chest X-ray.
Under Lombardi's leadership, 1,800 men and women were recruited into the clinical trial at Georgetown University Hospital as well as two other Georgetown community screening locations.
"Overall this study provides strong evidence that older patients who are at high-risk of developing lung cancer could benefit from CT screening and that's a significant finding." says Claudine Isaacs, MD, lead investigator of the NLST study at Lombardi. "We are grateful to all the men and women who participated in this important study. Clinical trials are critical to making progress in medicine."
"These results are very encouraging," says Louis Weiner, MD, director of Lombardi. "Studies like these generate so much excitement, but clearly there is much more work to be done. Lombardi and other NCI-cancer centers continue to explore effective ways to reduce lung cancer deaths including prevention efforts and by conducting clinical trials with the newest available cancer fighting drugs."
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. As of October 20, 2010, a total of 354 deaths from lung cancer had occurred among participants in the CT arm of the study, whereas a significantly larger 442 lung cancer deaths had occurred among those in the chest X-ray group. This represents a 20.3 percent reduction in lung cancer mortality offered by CT scans compared to the X-ray group.
"Potentially, we could save thousands of lives with CT screening, but keep in mind that because smoking causes many lung cancers, we could save hundreds of thousands more if people wouldn't smoke or quit if they do," Isaacs points out.
"We're proud to be a part of this important study designed to answer critical questions," says Howard J. Federoff, MD, PhD, executive vice president for health sciences at GUMC and executive dean of its School of Medicine. "Lombardi's leadership role in the effort to reduce the burden of cancer has an impact at the national and local levels, and benefits our community directly."
"This large and well-designed study used rigorous scientific methods to test ways to prevent death from lung cancer by screening patients at especially high risk," said Harold Varmus, M.D., NCI Director. "Lung cancer is the leading cause of cancer mortality in the U.S. and throughout the world, so a validated approach that can reduce lung cancer mortality by even 20 percent has the potential to spare very significant numbers of people from the ravages of this disease."
The NCI notes that the possible disadvantages of helical CT include the cumulative effects of radiation from multiple CT scans; surgical and medical complications in patients who prove not to have lung cancer but who need additional testing to make that determination; and risks from additional diagnostic work-up for findings unrelated to potential lung cancer, such as liver or kidney disease. In addition, the screening process itself can generate suspicious findings that turn out not to be cancer in the vast majority of cases, producing significant anxiety and expense. These problems must, of course, be weighed against the advantage of a significant reduction in lung cancer mortality.
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