Computed tomography scans widely marketed to consumers may not be valuable for mass screening of lung cancer, a Johns Hopkins study has found.
Results of the study, published in the Jan. 15 issue of the Journal of the American Medical Association, show that the number of lives saved by annual whole body CT screening may be outweighed by its costs and the harm of unnecessary testing for lung nodules identified that turn out to be benign. Screening was increasingly less cost-effective for those who quit smoking at the time of the first screening and for former smokers.
"Direct-to-consumer marketing and media coverage of CT trials has encouraged demand for lung cancer screening despite a lack of evidence for its efficacy," says lead author Parthiv J. Mahadevia, a research scientist at MEDTAP International in Bethesda, Md., who was a Robert Wood Johnson Clinical Scholar at Johns Hopkins when the study was completed. "These scans are not risk-free. There is a downside to this, including high costs and possible harm to individuals who may unnecessarily get invasive procedures if the scan detects a benign lung nodule."
An estimated 50 million men and women in the United States have smoked between the ages of 45 and 75, the authors note. If just half of this group received periodic annual screening, the program costs would be approximately $115 billion.
The National Cancer Institute has begun an eight-year trial comparing CT scans to chest X-rays in the diagnosis of lung cancer. But until there's solid data, consumers may want to hold off on the screenings, says senior author Neil R. Powe, director of Johns Hopkins' Welch Center for Prevention, Epidemiology and Clinical Research. Smoking cessation is the only proven, cost-effective method to reduce lung cancer risk, he says.
"We're not down on the technology, just its injudicious use," says Powe, also a professor of medicine and epidemiology. "CT can be a very useful tool, but only when recommended by a physician for a specific clinical purpose.
"Getting a scan does not mean doctors will detect cancer and save your life," Powe adds. "Doctors need to help patients think about their own personal risk for lung cancer, and whether this is worth it."
Researchers studied data from published lung cancer studies and from the Surveillance, Epidemiology and End Results national cancer database, known as SEER, then used this information to develop a computer program comparing annual CT screening to no screening in hypothetical groups of 100,000 60-year-old current smokers, in smokers who were in the process of quitting at the time of the first screening and in smokers who had quit five or more years prior to screening. The investigators measured benefits by comparing the difference in lung cancer deaths, and harm by the number of false-positive invasive tests or surgeries.
Over a 20-year period, there were 462,352 screening exams for current smokers. Researchers estimated 4,168 lung cancer deaths per 100,000 people who did not get screened, compared with 3,615 lung cancer deaths among those who were screened, yielding a reduction in mortality of 553 deaths, or 13 percent. However, there also were 1,186 invasive tests or surgeries for benign lesions in the screened group.
A cost-effectiveness analysis found that to save one year of "high-quality" life (called a "quality-adjusted life-year") would cost $116,300. Annual screening became progressively less cost-effective the longer former smokers had been smoke-free. The screening cost among those who quit at the start of screening was $558,600 per quality-adjusted life-year and for former smokers, $2.3 million per quality-adjusted life-year. Many other screening tests currently reimbursed by insurers and recommended by physician groups have cost-effectiveness ratios of less than $100,000 per quality-adjusted life-year. The study also found that screening was most cost-effective when started between ages 55 and 65, and that during the first two years of screening, there was a loss in cost effectiveness because of the harms and costs associated with unnecessary testing and treatment of benign masses. Gains in cost effectiveness did not appear until the third year of follow-up.
The computed tomography studied is called helical, or spiral, CT--technology introduced in the 1990s that can pick up tumors well under 1 centimeter in size. More than half the hospitals in the United States own the machines and routinely use them for diagnosing lung or other diseases in patients with symptoms.
The study was supported by the Robert Wood Johnson Clinical Scholars Program. Co-authors were Lee A. Fleisher, Kevin D. Frick, John Eng and Steven N. Goodman.