How accurate is CT screening for lung cancer?

January 01, 0001

How accurate is CT screening for lung cancer?

Direct-to-consumer promotion of lung cancer screening has increased, especially low-dose computed tomography (CT). However, screening exposes healthy persons to potential harms, and cumulative false-positive rates for low-dose CT have never been formally reported. These US authors quantified the cumulative risk that a person who participated in a 1- or 2- year lung cancer screening examination would receive at least 1 false-positive result, as well as rates of unnecessary diagnostic procedures in a randomized, controlled trial of low-dose CT versus chest radiography. Patients were current or former smokers, aged 55 to 74 years, with a smoking history of 30 pack-years or more and no history of lung cancer (n = 3190).

They found: "By using a Kaplan-Meier analysis, a person's cumulative probability of 1 or more false-positive low-dose CT examinations was 21% after 1 screening and 33% after 2. The rates for chest radiography were 9% and 15%, respectively. A total of 7% of participants with a false-positive low-dose CT examination and 4% with a false-positive chest radiography had a resulting invasive procedure.

The authors concluded: "Risks for false-positive results on lung cancer screening tests are substantial after only 2 annual examinations, particularly for low-dose CT. Further study of resulting economic, psychosocial, and physical burdens of these methods is warranted."

Evidence for benefit of any kind of lung cancer screening is not established.

For the full abstract, click here.

Annals of Internal Medicine 152(8):505-512, 20 April 2010
© 2010 to the American College of Physicians
Cumulative Incidence of False-Positive Test Results in Lung Cancer Screening-A Randomized Trial. Jennifer M. Croswell, Stuart G. Baker, Pamela M. Marcus, Jonathan D. Clapp, and Barnett S. Kramer. Correspondence to Dr. Croswell:

Category: R. Respiratory. Keywords: lung cancer, smoking, screening, computed tomography, radiography, false positive, randomized controlled trial, journal watch.
Synopsis edited by Dr Linda French, Toledo, Ohio. Posted on Global Family Doctor 11 May 2010

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