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From the Editor's Notebook |
rstanley{at}ajroffice.org
I was stimulated at that time by the writings of Drs. William Black and H. Gilbert Welch during the decade of the 1990s, and I am gratified to see that others have expressed similar concerns since then.
Although I have no hard data on the status of many of the entrepreneurial imaging centers offering whole-body CT examinations to healthy, asymptomatic adults, my sense is that they have lost their appeal and many have closed.
In my opinion, this type of screening is an inappropriate and potentially dangerous use of diagnostic imaging. To date, there has not been a single well-designed and scientifically valid study to show that the practice has any substantive value, despite the anecdotal testimonials to "lives saved" on popular TV talk shows.
An ongoing national lung tumor screening trial in high-risk individuals with a significant history of smoking, sponsored by the National Cancer Institute and American College of Radiology Imaging Network, has the potential to clarify the earlier results from the Mayo Lung Project, reported in the Journal of the National Cancer Institute in 2000 [2]. Although this screening trial is not comparable to screening healthy, asymptomatic adults, the likelihood is great that this study again will show that the long-term mortality rate from lung cancer will not be appreciably improved by earlier detection, despite the predictable increase in the 5-year survival rate [3].
In an area of nonradiologic screening, the prostate specific antigen (PSA) test now is being looked at carefully to determine if it does more harm than good. Dr. Thomas Stamey, professor of urology at Stanford and one of the earliest users of the PSA test for detecting and monitoring prostate cancer [4], has coauthored an article titled, "The Prostate Specific Antigen Era in the United States Is Over for Prostate Cancer: What Happened in the Last 20 Years?" [5]. The authors conclude that serum PSA was related to prostate cancer 20 years ago. In the last 5 years, serum PSA has been related only to benign prostatic hyperplasia. The authors state that there is an urgent need for serum markers that reflect the size and grade of this ubiquitous cancer. A study is cited showing that with each advancing decade of life, starting in the 20s, the presence of prostate cancer increases until 80% of men have prostate cancer in their 70s. That study indicated that "any...biopsy [of] the prostate has an excellent, age-dependent chance of being positive" [5].
The point of my prostate cancer comments is that the concept of cancer is not well understood. Many neoplasms that would be diagnosed histologically as cancer exist in a form that will do no harm to the person harboring the tumor throughout the extent of his life. Randomly imaging healthy, asymptomatic adults can result in the detection of such lesions. Once such lesions are "detected," a cascade of events follows that may do no good but may do harm to these individuals. Additionally, harm from unnecessary radiation exposure now is being more carefully considered. Brenner and Elliston [6] estimate a measurable risk potentially associated with full-body CT screening in a recently published article. It is encouraging to me to see perspectives on this potential problem also appearing in JAMA [7] and JACR [8].
AJR continues to publish articles on this issue as well. For example, in the October 2004 AJR, a study of the increased use of CT in detecting pulmonary embolism suggests that criteria should be developed so only patients who are most likely to benefit from these examinations have them [9]. Wise counseling on the part of the responsible radiologist will go a long way in educating our fellow clinicians, and I recommend a very insightful opinion piece by Phil Cascade on this topic [8].
Although radiologists usually are not in the business of ordering radiologic examinations, we nevertheless have considerable influence in the appropriate use of the array of imaging methods at our disposal. The value of an examination is not simply that it is readily available, but that it provides accurate information safely, efficiently, and appropriately to patients and practitioners.
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