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Beth Israel Deaconess Medical Center and Harvard Medical School Boston, MA 02215
I thoroughly enjoyed the spate of articles about screening in the October issue of the AJR [1, 2, 3, 4]. These articles were mostly critical of CT screening. As one who has devoted much of his career to pointing out unnecessary imaging [5], I would like to change positions and take a more supportive position regarding whole-body CT screening.
Those of us who have difficulty accepting the commercialization of screening in medicine [1] might find it helpful to think of these imaging examinations as analogous to the physical examination performed in the office. That time-honored screening examination is far less sensitive, and less expensive, than high-tech imaging, but its benefits are equally unproven.
Like the physical examination, most of what physicians do is based on anecdotal evidence or common sense judgments rather than on random controlled trials (RCTs). When Dr. Rogers [1] asks "where are the results of random controlled trials of whole-body CT screening" or Dr. Swensen [3] states that "we are unequivocally required as scientists and health professionals to thoroughly study this new `beast,'" they are, of course, correct. Who can argue with motherhood and apple pie? Screening mammography was mandated by Congress before any consensus was reached as to its benefit; even after multiple RCTs, some experts contend there is still no proof. I suspect that as with much of medical practice, there will never be consensus on this matter. Medicine is an art as well as a science and much of its practice is done—must be done—without the benefit of RCTs.
RCTs necessary to prove that use of an examination results in a disease-specific decrease in mortality, much less the gold standard of a decrease in long-term overall mortality, are costly. These trials are particularly difficult to assess when patients are being screened for multiple diseases at the same time, as is the case in whole-body CT screening. Additionally, methodology is changing so rapidly, particularly in high-tech specialties like radiology, that the results of RCTs may be rapidly rendered nonapplicable.
The statement is often made that screening is for the worried well [1]. Peace of mind is important. However, whole-body CT screening, and certainly screening mammography when it was also in its infancy, are less well suited for the worried patient, his or her worried primary physician, or the worried insecure radiologist who interprets the examination. How many times has a woman told me, in discussing her screening mammogram, that even if the chance of cancer was one in a 1000, she wanted the abnormality removed rather than followed up? Whole-body CT screening finds indeterminate or equivocal abnormalities far more frequently than does mammography. The societal costs of this examination can be extremely high if patients, physicians, and radiologists are unwilling to accept the small risks of either ignoring or following-up most of these lesions. Fortunately, as we discovered with screening mammography, false-positive results decrease with experience. There is no way that Swensen [3] is going to follow-up or perform a biopsy in each of the 51% of his participants who had noncalcified lung nodules, but he might have done so early in his experience.
Unfortunately, medicolegal concerns, as touched upon by Dr. Berlin [4], and the increasing inability of physicians and patients to tolerate diagnostic uncertainty [6] increase false-positives. The dollar cost of false-positives in screening mammography, including additional studies, follow-ups, referrals, and biopsies, is almost as much as the cost of the screening. Downstream costs for whole-body CT screening will be paid out of our finite health care resources, which takes us back to the fundamental issue of the individual versus societal trade-offs concerning selective screening.
Herman et al. [2] state that "mammography is the only diagnostic imaging examination currently in widespread use as a screening tool." I would add obstetric sonography and bone mineral measurements to that statement. None of these examinations had RCT proof of efficacy at the time of third-party-payment approval; in some instances, this documentation is still not available.
Interestingly, the distinction between screening and diagnostic examinations is becoming increasingly blurred. This is reflected in more nebulous and occasionally phantom indications for body CT and breast and fetal sonography.
Perhaps the greatest short-term benefit of screening is the less tangible incentive it brings to individuals to change their lifestyle. However, those factors, as well as possible ill effects from treatments of false-positives, would not be apparent on short-term RCTs measuring disease-specific survival.
Rogers [1] concludes about whole-body CT that "unfortunately, it appears that the information required to make an informed judgment is not available at this time." He is correct, but if medicine had waited for RCTs to assess the effects of antisepsis, anesthesia, antibiotics, and so forth, we might still be waiting. There is still a place for anecdotal and common-sense medicine—at least until the RCTs are completed. Physicians act on a myriad of commonly diagnosed abnormalities that are incidentally found on CT examinations performed for other reasons. I see no reason why they would not have equal expectations of benefit, hopefully out-weighing harm, when they treat (or elect not to treat) a similar abnormality diagnosed on a screening whole-body CT examination. You cannot have it both ways.
References
American Journal of Roentgenology
It is a free country. Indeed, if you are a physician, it is not illegal to perform whole-body CT scanning. As a radiologist, you are free to do so should you so desire. All it takes is a person who desires a whole-body CT scan and is willing to pay for it and a physician who is willing to perform it. Actually, payment is not required. You could perform the examination for nothing if that is your want to do. I may be rash, but I presume that the examination would not be performed without payment.
As long as both parties in this undertaking understand the limitations of the examination and potential implications of the findings disclosed—that is to say, there is truth in advertising—and the limitations of the examination are fully explained to the patient, it is probably ethical and it is most certainly legal to perform such an examination. However, the examination would seem to me to be unethical if based on false advertising claims made by wily and unscrupulous physicians as a siren call to the unwary and worried public.
In the end, the ethical judgment is rendered not on the whole-body CT examination itself, but on how the examination is advertised, presented, and interpreted.
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  C. D. Furtado, D. A. Aguirre, C. B. Sirlin, D. Dang, S. K. Stamato, P. Lee, F. Sani, M. A. Brown, D. L. Levin, and G. Casola Whole-Body CT Screening: Spectrum of Findings and Recommendations in 1192 Patients Radiology, November 1, 2005; 237(2): 385 - 394. [Abstract] [Full Text] [PDF]
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