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CT SCREENING FOR LUNG CANCER SAVES LIVES, PROMPTS SMOKERS TO QUIT
CHICAGO -- Mounting research suggests that using computed tomography (CT) to screen people 60 years and older who are at high risk for lung cancer may not only save lives, but has the extra benefit of convincing nearly a quarter of those screened to quit smoking, even though they don't have cancer, according to research being presented here today at the 85th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA).
"Lung cancer is considered a silent killer because there are no early warning signs. By the time it's detected, lung cancer is typically the size of an orange. By screening with CT, cancers can be found when they're smaller than the size of a grain of rice," said Claudia I. Henschke, M.D., Ph.D., professor of radiology and division chief of chest imaging at Weill Medical College of Cornell University, New York. "In cancers caught at the later stage, there's a 10 percent to 14 percent five-year survival rate, whereas for those caught early, survival moves up to 80 percent."
More than 160,000 people die of lung cancer every year in the United States, and it is the leading cause of cancer mortality in both men and women, according to the American Lung Association. Those who quit smoking decrease their risk of getting lung cancer, but even after 20 years, smokers and former smokers remain at more than twice the risk of developing lung cancer as non-smokers. Both smokers and former smokers are the at-risk individuals targeted by the on-going study.
Those at risk for developing lung cancer were defined by the study as men and women 60 years or older who smoked at least a pack of cigarettes every day for at least 10 years, or two packs a day for 5 years.
Repeat CT Screening Catches More Lung Cancers
The study reported on second-year data from the Early Lung Cancer Action Program (ELCAP), developed by researchers at Weill Medical College of Cornell University and New York University Medical Center. In phase one, reported at RSNA last year, 1,000 smokers and former smokers had baseline screenings using CT, which proved to be much better at detecting early cancers than standard chest X-ray. In phase two, researchers are reporting results of 808 smokers and former smokers based on their multiple annual repeat screenings, a total of 1,398 person-years of annual CT screening.
Seventy-eight subjects had nodules on repeat annual screening CT, yielding a rate of
6 percent (78/1398). These nodules can be signs of pneumonia, viral inflammation, benign calcifications or cancer. Nine of these subjects were found to have small tumors, either first appearing on the annual screening or missed on the prior screening. In the others, the nodules either resolved after treatment with antibiotics or are being followed to determine growth.
"This demonstrates why yearly screening is important," said Dr. Henschke. "Before we can recommend this as a national screening program, we must follow the subjects with lung cancer to determine the cure rate to prove that lives would be saved by using CT to annually screen smokers and former smokers for lung cancer."
The Japanese already use CT to annually screen those at risk for lung cancer. CT lung cancer screening is also in the early stages at the Mayo Clinic, Rochester, Minn.; H. Lee Moffitt Cancer Center, Tampa, Fla.; and at one site each in Germany and Israel.
CT Screening Prompts Many Smokers to Kick the Habit
A related study shows ELCAP had the unexpected and positive benefit of convincing 23 percent of those screened to quit smoking, whereas the national annual rate of smoking cessation is about 6 percent, said Dr. Henschke. Another 23 percent were convinced to cut back. Prior to the baseline screening, half of all of the people screened had already quit smoking. Men were more likely to quit than women, results showed.
"When we reviewed the CT images with those screened, they also showed the extent of emphysema people had," said Dr. Henschke. "Emphysema makes the lungs look like Swiss cheese with big empty holes in place of the normal lung tissue and many were unaware they had this disease."
Emphysema can be caused by smoking, which irritates the tiny airways in the lung. The airways become inflamed, heal and scar. Air gets trapped in the airways, which eventually rupture. When people with severe emphysema breathe, they feel as though they can't exhale all of the air they've inhaled.
Co-authors of a paper on the ELCAP program being presented at RSNA by Dr. Henschke are: David P. Naidich, M.D.; David F. Yankelevitz, M.D.; Dorothy I. McCauley, M.D.; Georgeann McGuinness, M.D.; James P. Smith, M.D.; Daniel Libby, M.D.; Mark Pasmantier, M.D.; and Olli Miettenen, M.D.
In addition to Dr. Henschke, co-authors of a paper on those in the ELCAP program who were prompted to quit smoking are: Natasha Buckshee, M.D.; Carol Mancuso, M.D.; and David F. Yankelevitz, M.D.
The RSNA is an association of 31,000 radiologists and physicists in medicine dedicated to education and research in the science of radiology. The Society's headquarters are located at 820 Jorie Blvd., Oak Brook, Illinois 60523-2251.
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Note: Copies of 1999 RSNA news releases are available online at http://www.pcipr.com/rsna beginning Monday, Nov. 29.
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