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How would you characterize the International Early Lung Cancer Action Program (I-ELCAP) results?
First, Dr. Henschke and her colleagues should be commended. The results suggest the optimism about potentially using spiral CT to screen at-risk patients for lung cancer is well founded.

But, to make truly informed decisions and policy about lung cancer screening, we must understand certain things, even beyond whether it actually decreases mortality, such as the disease's natural progression and the long-term effects of screening-driven interventions. We still don't have this information.

For example, when small nodules are found in screening participants, without invasive follow-up there is no way to distinguish nodules that could progress to a deadly cancer. We also don't have a clear definition of who is at high risk for developing lung cancer. NCI is working to develop validated risk models that will help identify those at highest risk who might benefit most from screening.

Will the National Lung Screening Trial (NLST) address these types of issues?
Because it's a randomized trial with more than 53,000 participants, NLST is different than I-ELCAP in several important ways. NLST should provide definitive evidence about whether there is a true mortality benefit associated with lung cancer screening using CT or chest x-ray.

NLST will also help to answer questions about the medical resources required for follow-up on screening results, the effect of screening on quality of life, and its influence on smoking behaviors and beliefs. NLST is also developing a collection of specimens that is expected to be a valuable resource for years to come.

This is a complex issue. What should the public take away from all of this?
First, for anybody who is still smoking, the most effective way to reduce your risk of lung cancer is to stop.

Second, we just don't know if early diagnosis of lung cancer by spiral CT reduces deaths from the disease, but many people concerned about their lung cancer risk may seek screening. The decision to be screened for lung cancer is an individual one, so it's important that these individuals discuss this with their health care provider, who can assist in weighing the pros and cons for their situation.

It's also important to understand that lung cancer screening is not a test, but a process. Screening results lead to diagnostic workups, which may include follow-up CT scans and/or a lung biopsy. Lung biopsies pose their own risks, and can result in significant complications. Individuals who do get screened should do so at facilities with extensive screening expertise and experience.