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National Lung Cancer Screening Trial

Lung cancer is currently the leading cause of cancer-related deaths in the United States, claiming more lives than breast, colon and prostate cancers combined. Early detection methods to date have proven somewhat ineffective, and most lung cancers are diagnosed only after symptoms appear. By this time, the cancer has spread outside the lung in up to 30% of cases. Given this fact, researchers have sought to develop methods to screen for the disease before symptoms become evident and treatment options are limited.

In 2002, the National Lung Cancer Screening Trial, sponsored by the National Cancer Institute, was launched with the goal of comparing two ways of detecting lung cancer -- standard chest x-ray versus low-dose helical (spiral) computed tomography (CT) -- and their relationship to lung cancer death rates in a high-risk population of more than 53,000 current or former heavy smokers. In order to qualify for the trial, participants had to be between the ages of 55 and 74 and smoked at least a pack a day for 30 years or more. This randomized clinical trial was conducted at 33 sites across the country over a period of five years.

By 2010, enough data from the trial was available to determine that the study’s primary objective had been met, and that the group receiving the low-dose helical CT scan derived benefit. Overall, researchers found 20% fewer lung cancer deaths occurred in the trial group screened with CT. Additionally, they determined that deaths of participants due to any cause (including lung cancer), was 7% lower in the CT-scanned group. The National Cancer Institute agreed with the Data and Safety Monitoring Board (DSMB) that this information should be made public.

Prior to the release of the results of this study, there had been no guidelines issued for lung cancer screening of at-risk patients, and because CT scans for early detection were not covered by most insurance, primary care physicians did not refer patients for a scan. Does access to this knowledge now dictate that all at-risk patients should have regular CT scans to screen for lung cancer? At this time, probably not. The risk associated with repeated CT scans is still undetermined. Investigators with the National Lung Cancer Screening Trial will continue to analyze data to see how radiation exposure from three low-dose CTs affect a person’s lifetime risk for cancer. Previous studies have shown there may be some risk involved, but it is important to remember that the amount of radiation used in a low-dose CT is not comparable to that of a diagnostic CT. The question then becomes whether the benefit of finding a treatable or potentially curable cancer in a current or heavy smoker outweighs the risk.

After a more in-depth analysis of the findings of the trial, investigators will prepare articles for publication in peer-reviewed journals for release late in the summer of 2011. In the meantime, most of the medical community, while eager for more details, is taking a wait-and-see approach toward the development of screening programs at their institutions. Many issues such as cost-effectiveness, false positives which could lead to potentially unnecessary and risky procedures, how many diagnoses are actually accomplished in early stage and how screening plays a role in both short and long-term smoking behavior are yet to be addressed.