Lung Cancer Screening with Low-dose Computed Tomography Associated with High Rate of False Positives

Individuals who undergo lung cancer screening with low-dose computed tomography (LDCT) are at a high risk for receiving false-positive results, according to the results of a study presented at the 2009 annual meeting of the American Society of Clinical Oncology in Orlando, Florida.[1]

Lung cancer is the most common cancer in the world and is the leading cause of cancer death, with 160,000 deaths in the United States annually. No screening procedure for lung cancer has been proven to decrease the number of lung cancer deaths, and there is currently no consensus as to the best way to screen for lung cancer. Historically, physicians have used imaging tests (such as LDCT and chest X-ray) and sputum cytology to detect lung cancer. New screening procedures continue to be evaluated and refined.

Researchers from the National Institutes of Health (NIH) conducted a study that involved 1,610 patients who underwent screening with LDCT and 1,580 who underwent screening with chest X-ray. All participants in the study were current or former smokers between the ages of 55 and 74. All subjects underwent baseline screening followed by another screening exam one year later. They were then followed for an additional year.

A positive screen was defined as any noncalcified nodule greater than 4 millimeters or any other radiographic finding deemed suspicious for cancer. A false-positive was defined as a positive screen that was then followed by a completed negative work-up or 12 or more months of follow-up with no cancer diagnosis. After analyzing the screening results, the researchers then quantified the cumulative risk of receiving a false-positive result from lung cancer screening. In the LDCT group, the risk of a false-positive result was 21% after one scan and 33% after the second. In the chest X-ray group, the risk of a false-positive result was 9% after one X-ray and 15% after the second.

The researchers concluded that there is a significant risk of receiving a false-positive result with LDCT screening and this could result in a potential economic burden on the system as well as cause unnecessary stress among individuals being screened.


[1] Crosswell JM, Baker SG, Marcus PM, et al. Cumulative risk for a false-positive test using low-dose computed tomography in lung cancer screening. Presented at the 2009 annual meeting of the American Society of Clinical Oncology, May 29-June 2, 2009, Orlando, FL. Abstract CRA1502.

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