Commentary: CT screening for lung cancer - Caveat emptor

The American Cancer Society states that: "Efforts at early detection (lung cancer) have not yet been demonstrated to reduce mortality." "Newer tests, such as low-dose spiral CT scans and molecular markers in sputum, have produced promising results in detecting lung cancers at earlier, more operable stages when survival is better. However, there are considerable risks associated with lung biopsy and surgery that must be considered when evaluating the risks and benefits of screening" [32]. The American College of Chest Physicians in their evidenced-based guidelines made the following recommendations: "We do not recommend that low dose CT be used to screen for lung cancer except in the context of a well-designed clinical trial" [5]. At present, no physician-based medical organization recommends screening for lung cancer in asymptomatic individuals, even if they are at high risk. Table 4 outlines the drawbacks or limitations of CT screening. A number of these points have been addressed above. Currently, there are two large randomized screening trials that are nearing completion. The National Lung Screening Trial (NLST) is a multicenter trial that randomized >53,000 high-risk participants (2002-2004) to low-dose CT screening or chest radiography [33, 2]. Participants received a prevalence and two annual incidence rounds of screening. All participants were followed yearly by questionnaires after the screening rounds. Death certificates will be obtained on all deaths and the National Death Index will be searched for any participants lost to follow-up. Cumulative lung cancer mortality through August 2008 will be determined. The NLST is designed to be able to detect as little as a 20% decrease in mortality. These results will be reported in 2010. The NELSON trial (Netherlands, Belgium, and Denmark) was launched in 2003, 1 year after the NLST [34]. High-risk participants were randomized to low-dose CT screening or no screening of any type. CT scans are performed at baseline, year 1, and year 3. Almost 20,000 participants have been enrolled, and the study will have an 80% power to detect a mortality reduction of 25%. These results will likely be available soon after the NLST trial results are known. Based on the significant limitations in the results reported to date from nonrandomized, observational screening trials, we do not recommend CT screening for lung cancer. Results of these two large randomized controlled trials may provide the needed proof of efficacy in mortality reduction from screening.