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Commentary on Drs Miettinen and Henschke’s Viewpoint¹

¹ From the Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710 (E.F.P., P.C.G.); and the Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH (W.C.B.). Received March 15, 2001; accepted March 20. Address correspondence to E.F.P. (e-mail: patz0002@mc.duke.edu).

Index terms: Computed tomography (CT), utilization • Lung neoplasms, CT, 60.12111 • Lung neoplasms, diagnosis • Lung neoplasms, screening • Lung neoplasms, staging

	INTRODUCTION

TOP INTRODUCTION REFERENCES

 
The utility of lung cancer screening has been debated for many decades, but despite numerous clinical trials, the fact remains that no scientific study has clearly shown screening for lung cancer to be effective. This is by no means a nihilistic perspective but an appropriately skeptical one. The most well-conceived theories are not always validated in clinical practice, and as confirmed many times before, "there is nothing more deceptive than an obvious fact."

We are sympathetic with the practicing radiologist whom Drs Miettinen and Henschke describe (1). As chest radiologists, we also used to be confident that many lung cancer deaths could be prevented by means of early detection. However, we have come to realize that we cannot safely infer from our clinical observations the effectiveness of screening with computed tomography (CT). Over the past several decades, our fundamental understanding of cancer has changed dramatically. Cancer is now understood to be a complex, multistep process resulting from aberrant genes and environmental factors. Because the natural history of small lung cancers detectable at CT is so variable, the effectiveness of screening can only be reliably determined in a randomized clinical trial with a mortality end point. This is the only study design that can ensure comparability between the screened group and the control group and allow us to determine the effect of screening.

Are we demanding too much from CT screening trials in the effort to prove that this technique is effective? We do not believe this to be the case. It was once thought that screening with chest radiography would reduce lung cancer mortality more than 50% on the basis of the same arguments used to justify screening with CT today. However, 30 years later, the most recent follow-up of the Mayo Lung Project shows slightly more deaths from lung cancer and other causes in the screened group than in the control group (2). This excess of deaths suggests that screening with chest radiography is at least as likely to cause a net harm as a net benefit. Undoubtedly, lack of compliance in the screened group, contamination in the control group, and a short intervention period (6 years) diminished the observed effect of screening in the Mayo Lung Project. However, these deficiencies could not have caused an excess of deaths in the screened group if screening had really conferred a major net benefit.

We all want to reduce lung cancer mortality as fast as possible, but we should not rush headlong into screening with helical CT. We should first verify that this form of screening is indeed effective and that its benefits outweigh its harms. Today, we have a unique opportunity to test these hypotheses and move forward through a logical rigorous discovery and validation process.

	FOOTNOTES

 
See also the articles by Patz et al (pp 587–591 ) and Miettinen and Henschke (pp 592–596 ) in this issue.

	REFERENCES

TOP INTRODUCTION REFERENCES

 

1. Miettinen OS, Henschke CI. CT screening for lung cancer: coping with nihilism. Radiology 2001; 221:592-596.[Abstract/Free Full Text]
2. Marcus PM, Bergstralh EJ, Fagerstrom RM, et al. Lung cancer mortality in the Mayo Lung Project: impact of extended follow-up. J Natl Cancer Inst 2000; 92:1308-1316.[Abstract/Free Full Text]

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This Article Full Text (PDF) All Versions of this Article: 2213010618v1 221/3/597    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Patz, E. F. Articles by Goodman, P. C. Search for Related Content PubMed Articles by Patz, E. F., Jr Articles by Goodman, P. C.