If it moves, radiologists will want to screen it

I wrote a column for DI Europe six years ago about screening programs, stating that screening approaches that are not based upon firm foundations become ideological crusades. The outcry was earsplitting. Somebody delivered a broadside against me claiming I would undermine dozens of years of hard work in mammography.

I had pointed out that it was neither my business nor my intention to either bless or damn the use of screening in those groups that would benefit from, in that particular case, x-ray mammography.

"A critical approach is necessary," I wrote. "Two points should never be forgotten: The screening procedure must have a clear advantage for the person screened, and the population must not be left in doubt about its reliability. If these philosophies are not adhered to, the public will lose faith in the screening test and in the people proposing and performing it. . . . I believe that screening in general is an important and necessary task for medical professionals."¹

What has happened in half a decade? Nothing much has changed in mammography. The U.S. National Cancer Institute summarizes the state of affairs: "Several large studies conducted around the world show that breast cancer screening with mammograms reduces the number of deaths from breast cancer for women aged 40 to 69, especially those over age 50. Studies conducted to date have not shown a benefit from regular screening mammograms, or from a baseline screening mammogram (a mammogram used for comparison), in women under age 40."²

Lung screening is different. "Are you a smoker? Then you are at high risk of contracting lung cancer! To rule out cancer at a very early stage you should periodically undergo CT-based screening, a low-dose x-ray examination of your lungs costing less than EUR250 (tax included)!"

I have slightly re-phrased this advertisement seen in a private radiology office somewhere in Europe. I found it unpleasantly close to the edge of being unethical. Many private radiologists are in tough straits, anxiously looking for increased returns on their heavy investments in multislice CT and high-field MRI.

But would I, the leading hypochondriac in town, undergo such an examination? Yes! Immediately! Lung cancer is one of the leading causes of cancer death, and those at greatest risk are identified readily on the basis of age and smoking history. By the way, I don't smoke-unless I am given a Havana cigar.

The radiologist's argument in favor of his offer, which is not reimbursed by any health insurance in his country of residence, is that MSCT will identify small lung lesions at a higher rate than chest x-ray. The individual can then be treated and saved from dying of cancer.

The problem is that there is no proof. On the contrary, the 20-year follow-up of the Mayo Lung Project showed no statistically significant reduction in lung cancer mortality among men who had been offered intense screening compared with those who had not. It additionally suggested that some lung cancers detected through screening have limited clinical relevance.³

The authors of this follow-up study pointed out that their findings only added to the controversy surrounding low-dose MSCT as a lung cancer screening test. They noted that if lung cancer lesions with limited clinical relevance truly exist, then CT may do more harm than good.³

Other research groups have emphasized this point. Dr. Peter Bach and colleagues at the Memorial Sloan-Kettering Cancer Center in New York City observed that while screening for lung cancer with low-dose CT may increase the rate of lung cancer diagnosis and treatment, it may not lead to a meaningful reduction in the risk of advanced lung cancer or death from lung cancer. They stressed that until more conclusive data are available, asymptomatic individuals should not be screened out-side of clinical research studies that have a reasonable likelihood of further clarifying the potential benefits and risks.⁴

Prof. William Black, director of chest radiology at the Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, added his views in a review paper. He noted that CT screening can cause additional harm, for example, from false-positive test results and overdiagnosis.⁵

Even worse, the talk of the town at the 2007 annual meeting of the RSNA in Chicago was an article that had just been published in The New England Journal of Medicine. The paper discussed the growth in the use of CT and the increase in patient radiation exposure. It claimed that CT scanning could be responsible for as many as 2% of all cancers diagnosed in the U.S. over the next 20 to 30 years.⁶

The next step is whole-body scanning. If your health, and that of your partner, your children, your parents, and your in-laws is at stake, a guilty (though misguided) conscience will nag: "Perhaps I should offer them such an examination. Let's keep out of harm's way and get peace of mind. What can we lose?"

Turning medicine or, in this instance, radiology, into an exact, predictive science will not work, because that is not what medicine is. When you read the hundreds of images of a whole-body study carefully enough, you will find something "abnormal" in any asymptomatic person. Then what do you do? The easiest way out is to overlook that finding or propose a reexamination in six months' time.

That is unethical. The study was unethical too. Two unethical things don't cancel each other out. Otherwise you have to kick off an avalanche of additional tests. Half a year and EUR50,000 later, you can tell the client (now a patient) that he/she is healthy-except for the laparotomy scar and the sleepless nights due to worry. There was no peace of mind; quite the contrary. One passes quickly through a gray zone into screening techniques that have no evident benefit for the person studied.

Screening is a little like playing the lottery; you might win, or you might lose. Whole-body CT or MRI screening belongs to these lotteries. Its only advantage over plastic surgery is that you will not die on the table.

Screening differs from clinical practice. It targets apparently healthy people, offering to help individuals make more informed choices about their health. The U.S. Food and Drug Administration (FDA) offers the following advice:

"Taking preventive action, finding unsuspected disease, uncovering problems while they are treatable, these all sound great, almost too good to be true! In fact, at this time the FDA knows of no scientific evidence demonstrating that whole-body scanning of individuals without symptoms provides more benefit than harm to people being screened. The FDA is responsible for assuring the safety and effectiveness of such medical devices, and it prohibits CT manufacturers from promoting their systems for use in whole-body screening of asymptomatic people. The FDA, however, does not regulate practitioners, and they may choose to use a device for any use they deem appropriate."⁷

Drs. David Brenner and Eric Hall from the Center for Radiological Research at Columbia University in New York concluded in the NEJM paper that, "When a CT scan is justified by medical need, the associated risk is small relative to the diagnostic information obtained. However, if it is true that about one-third of all CT scans are not justified by medical need, and it appears to be likely, perhaps 20 million adults and, crucially, more than one million children per year in the U.S. are being irradiated unnecessarily."⁶

Many different organizations have set up straightforward criteria for screening, including the World Health Organization and the U.K. National Screening Committee.^8,9 The following are taken from the U.K. criteria:

• The condition should be an important health problem.
• The epidemiology and natural history of the condition, including development from latent to declared disease, should be adequately understood, and there should be a detectable risk factor, disease marker, latent period, or early symptomatic stage.
• There should be a simple, safe, precise, and validated screening test.
• There should be an agreed policy on the further diagnostic investigation of individuals with a positive test result and on the choices available to those individuals.
• There should be an effective treatment or intervention for patients identified through early detection, with evidence of early treatment leading to better outcomes than late treatment.
• Clinical management of the condition and patient outcomes should be optimized in all healthcare providers prior to participation in a screening program.
• There should be evidence from high-quality randomized controlled trials that the program is effective in reducing mortality or morbidity.
• There should be evidence that the complete screening program (test, diagnostic procedures, treatment/intervention) is clinically, socially, and ethically acceptable to health professionals and the public.
• The benefit from the screening program should outweigh the physical and psychological harm (caused by the test, diagnostic procedures, and treatment).
• The cost of the screening program (including testing, diagnosis, and treatment, administration, training, and quality assurance) should be economically balanced in relation to expenditure on medical care as a whole (i.e., value for money).
• Evidence-based information, explaining the consequences of testing, investigation, and treatment, should be made available to potential participants to assist them in making an informed choice.

Yet the public health environment insists that lung or whole-body screening is a public health issue that should not be questioned. Skepticism, even when endorsed by scientific results, might just delay action; and any action is good. They don't see that action for the sake of action can be very harmful.

When lining up for the security check at an airport a few weeks ago, I suddenly thought, "This is like medical screening, so the outcome should be assessed like that of medical screening." I checked the literature when I came home and found that somebody else already had had the idea. A U.S. group had published a paper on it.¹⁰

Approximately 2000 people have died as a result of explosives on airplanes since 1969. A similar number have been killed in attacks on trains. Yet there is no screening of railroad passengers, apparently without major harm.

The authors argue that by analogy, in medical screening this would be like screening the left breast with x-ray mammography but not the right breast. They concluded: "Of course, we are not proposing that money spent on unconfirmed, but politically comforting, efforts to identify and seize water bottles and skin moisturizers should be diverted to research on cancer or malaria vaccines."

The manner in which airport checks are performed resembles the comment made to me by a patient regarding his annual prostate examination."I always go to my prostate screening; therefore I have not gotten cancer," he said.

The "therefore" is wrong. There is no causality between making visits to the doctor and getting cancer.

On the other hand, remember the story of the man who entered the U.S. and after the security check was told: "You should get the opinion of a real medical doctor concerning your prostate as quickly as possible."

PROF. DR. RINCK is visiting professor at the University of Mons in Belgium. He can be reached at peter.rinck@umh.ac.be

References

1. Rinck PA. Screening programs must show clear benefits. Diagnostic Imaging Europe 2002;18(5):12-13.
2. National Cancer Institute. Screening mammograms: questions and answers.

www.cancer.gov/cancertopics/factsheet/Detection/screening-mammograms

, accessed April 10, 2008.
3. 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(16):1308-1316.
4. Bach PB, Jett JR, Pastorino U, et al. Computed tomography screening and lung cancer outcomes. JAMA 2007;297(9):953-961.
5. Black WC. Computed tomography screening for lung cancer: review of screening principles and update on current status. Cancer 2007;110(11):2370-2384.
6. Brenner DJ, Hall EJ. Computed tomography-an increasing source of radiation exposure. NEJM 2007;357(22):2277-2284.
7. U.S. Food and Drug Administration. Whole body scanning using computed tomography (CT).

www.fda.gov/cdrh/ct/

, accessed April 10, 2008.
8. Wilson JM, Jungner YG. [Principles and practice of mass screening for disease.] Bol Oficina Sanit Panam 1968;65(4):281-393. Spanish.
9. U.K. National Screening Committee. Criteria for appraising the viability, effectiveness and appropriateness of a screening programme

www.nsc.nhs.uk/uk_nsc/uk_nsc_ind.htm

, accessed April 10, 2008.
10. Linos E, Linos E, and Colditz G. Screening programme evaluation applied to airport security. BMJ 2007;335(7633):1290-1292.