A Conversation with Drs. Denise Aberle and Christine Berg, NLST Co-Directors
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The recent announcement of ABC-TV News' Peter Jennings' lung cancer diagnosis has increased public interest in the effectiveness of screening tests to detect and reduce mortality from lung cancer. NCI is supporting the National Lung Screening Trial (NLST) to address this question. NLST compares whether chest X-ray (CXR) or spiral CT scan is more effective in reducing lung cancer deaths among high-risk individuals.
What's the status of NLST?
Dr. Berg: We're in the third and final year of screening for many of the participants. We anticipate we'll be done with screening by late 2006 or early 2007.
Some news reports about Mr. Jennings' diagnosis include statements by physicians recommending spiral CT screens, claiming they are more effective than CXRs. Might this have a negative impact on retention of NLST enrollees?
Dr. Aberle: It's a concern, but one to address by answering questions of our participants individually and through trial updates. There's a difference between screening healthy people and diagnosing symptomatic patients, such as Mr. Jennings. The media focuses on spiral CT because it is new technology and detects smaller lesions, inferring - incorrectly - that CT can prevent lung cancer deaths. We just don't know that. We do know that CT detects many more lung nodules (most benign) and even more cancers, many of which are very slow growing. But we have not seen that CT screening reduces the number of lethal cancers or that it has benefits that outweigh the risks associated with diagnostic work-up of additional nodules.
How do you ensure the safety of participants?
Dr. Berg: We have several protections. First, great care and thought by many experts went into NLST's design. Second, each site has an Institutional Review Board responsible for ensuring thorough consent process and the protection of the subjects. Third, sites report all trial-related events and complications, all of which are regularly reviewed by an independent Data and Safety Monitoring Board that recommends changes or even stopping the trial if trends are seen that suggest possible harm to any group of participants.
When will we know results from NLST?
Dr. Berg: The current schedule is for follow-up to end in 2008 and for final data analysis in 2009.
Dr. Aberle: If we don't see some decrease in advanced-stage, lethal lung cancers with CT, that may also provide early evidence that CT doesn't offer a screening advantage over CXR. We would expect to see that sooner than mortality differences. But, NLST is critically important because it offers the potential to identify a screening test that may reduce the burden of death from lung cancer.