Does CT Lung Cancer Screening Meet the Criteria for an Effective Screening Test?

Many of you have already read the study by Claudia Henschke, M.D., Ph.D., et al., in the October 26, 2006, edition of the New England Journal of Medicine, entitled “Survival of Patients with Stage I Lung Cancer Detected on CT Screening,” or you may have read about it on the front page of the New York Times. My purpose here is not to debate the results of Dr. Henschke’s work, but to provide some background on the controversial subject of lung cancer screening with CT and to offer suggestions about how to respond to patients who are interested in this exam.

Because chest radiography for lung cancer screening, dating back to the 1950s, has not seemed viable, interest began to turn to CT in the 1990s. Dr. Henschke and colleagues’ study, the “Early Lung Cancer Action Project” (ELCAP), was the first to look at CT as a screening modality, with initial results published in 1999. They have now published their final data, looking at survival rates as an endpoint. Their study does, in fact, demonstrate improved survival with CT screening. But as Drs. Stephen Swensen and Elliott Fishman point out in the New York Times article, this study should be viewed with caution since there was no control arm. Also, studies using survival rate as an endpoint for a screening test are subject to statistical biases such as lead-time bias, length-time bias and overdiagnosis.

I currently advise against recommending CT lung cancer screening to your patients. Hopefully, by the end of the decade, we will have data from the National Lung Cancer Screening Trial that specifically addresses mortality rates with CT screening. For those of you interested in further reading on lung cancer screening, I have included important references. If you have questions for me, please feel free to call at 503-216-4830.

Steven Zinck, M.D.
Thoracic Imaging Section Chief
The Radiology Group, P.C., at
Providence St. Vincent Medical Center,
and the Center for Medical Imaging