Weighing value, risk of full-body scans

There are more than 108 commercial imaging facilities in the U.S., offering heart, lung, brain and other scans to asymptomatic people. Under what circumstances is it ethical for a doctor to own and operate a self-referral, full-body imaging facility?

Reply

Recent events have placed the practice of self-referred, elective, full-body screening in the spotlight. Study results published in the New England Journal of Medicine in the last year suggest that CT screening may increase survival rates among asymptomatic patients with early-stage lung cancer. Direct-to-consumer advertising continues to spark demand among a health-conscious patient population. And, although the practice is not currently supported by organized medicine, its growing popularity and public interest are outpacing the availability of evidence about its efficacy.

Proponents argue that its potential risks are outweighed by the benefits of early detection for many common, serious diseases and the potential increase in survival rates through early intervention. Meanwhile, the ethical implications of widespread screening that may affect the health of tens of thousands of individuals have garnered little attention.

Typical full-body CT exams evaluate the chest, abdomen and pelvis for cancer, cardiovascular disease and other presymptomatic disease findings. Centers have begun offering specialized services, including CT lung screening for patients with a history of smoking, coronary calcium scoring to assess heart disease, and CT colonoscopy to detect or prevent early colon cancer.

Physicians involved in self-referral imaging centers have to balance the basic medical ethics principles of nonmaleficence and respect for patient autonomy. We have a duty to not expose patients to unnecessary harm from screening exams, while promoting their right to make decisions about their health by offering exams that have a reasonable potential to benefit them.

The concern about unnecessary radiation exposure is real; the effective radiation dose from chest and abdominopelvic CT scans approaches the range experienced by atomic bomb survivors who later were found to have a statistically significant increase in solid cancer risk and mortality. The comparison between the number of cancers that could be caused by this exposure and the number that might be detected early enough to benefit asymptomatic patients is uncertain.

Incidental abnormalities are common but still require diagnostic work-up and management. The follow-up radiation and invasive diagnostic procedures that must be performed to confirm false-positive results often cause patients anxiety and loss of productivity.

While full-body screening is not reimbursed by most third-party payers, all follow-up diagnostic studies and interventions for incidental abnormal findings typically are covered. If whole-body screening becomes mainstream, society may be burdened by the additional cost of screening and follow-up. While self-referring physicians may profit from out-of-pocket payments from patients, the increased overall health expenditures will be passed on to the public through higher insurance premiums.

Given the lack of evidence for full-body screening's effectiveness, physicians involved in centers that offer the service must provide thorough informed consent to patients. That is, before any screening exam, physicians must outline the benefits, risks, alternatives and associated costs (emotional, physical and economic) of the procedure. Physicians also must disclose their financial interest if they are referring patients to their own imaging centers.

For asymptomatic full-body screening to become an acceptable, ethical practice, more research is needed into its effectiveness at identifying disease early enough to increase survival rates for different types of cancers. Possible benefits must be weighed against radiation-induced cancers and increased morbidity and mortality from interventions that must follow false-positive results. More detailed cost-effectiveness models are needed to project economic and quality-of-life costs associated with screening for both the individual and society.

Howard P. Forman, MD, MBA, professor of diagnostic radiology, management and public health, Yale University, Connecticut

Christoph L. Lee, MD, Dept. of Diagnostic Radiology, Stanford University School of Medicine, California

Reply

Full-body screening is being marketed to healthy, asymptomatic individuals who have the financial resources to pay the direct cost of the test. One national telephone survey revealed that 86% of people would have a full-body scanning, if offered free; 85% would prefer receiving a full-body scan to receiving $1,000 cash.

The guiding ethical principle for physicians who wish to open a full-body scanning service should be beneficence, to which they have sworn an oath; the effect of their actions should result in net benefit. There should be clear evidence that the technology has a proven net benefit and that the process of administering the testing upholds the integrity of the profession.

What is the current evidence for the benefits and harms of full-body scanning?

There are no data from randomized trials that examine the impact of full-body scanning on health outcomes, but it is possible to extrapolate from information about the performance of CT in screening for lung cancer and coronary heart disease.

A study of high-risk smokers reported in Radiology in 2005 found lung cancer in only 1.7% of those screened, while 74% had at least one uncalcified pulmonary nodule.

If these findings are extrapolated to the 90 million current and past smokers in the U.S., screening would identify more than 180 million uncalcified nodules, with only 2% proving malignant after five years of follow-up. The ratio of false-positive to true-positive findings would be even higher in a lower-risk population of younger nonsmokers.

The premise in scanning for coronary artery calcification is that detection of subclinical atherosclerosis could guide preventive strategies. Although there is ample evidence that coronary calcification predicts risk for cardiovascular disease and overall mortality, there are no data, independent of risk factors, that screening improves health outcomes or motivates behavioral change, as is often purported.

Normal findings may lessen a person's anxiety about risk of disease, and the act of undergoing screening could lead to changes in lifestyle by causing patients to pay more attention to risky behaviors.

A study published in Cancer in 2003 found that individuals who were smokers and participated in a study of CT screening for lung cancer reported a higher rate of abstinence one year after screening than would have been expected in other cohorts.

Direct-to-consumer marketing of full-body scanning frequently preys on people's sense of vulnerability. Advertisements for the service contain statements that evoke negative emotions in listeners about their health, thus creating an incentive to obtain the respective test.

Many of the potential harms are well-recognized: the risks of false-positive results that must be investigated; exposure to high doses of radiation; and the cost to patients for the scans and to insurers for follow-up treatment. But more subtle negative consequences are unappreciated. Here are just a few:

Quality of life. Small decrements in quality of life -- office visits, time away from work, unnecessary concern -- have a substantial net effect when accumulated over large, healthy screening populations.

Overdiagnosis. Conditions are diagnosed -- and then treated -- that would not have become clinically significant.

Early diagnosis. This may not improve outcomes and could lead to worse outcomes; patients might undergo risky diagnostic and therapeutic interventions earlier in the course of disease, leading to earlier complications without resultant benefit.

Future insurability. Most health insurance policies seek to exclude patients with known health conditions. Even in asymptomatic individuals, conditions uncovered with full-body imaging may have implications for future insurability.

Psychological effects. Receiving positive or suspicious test results is associated in the short term with anxiety, depression, poorer perceptions of health and psychological distress.

It will be ethical for a physician to own and operate full-body scanning centers when there is evidence that screening is associated with improvement in patient-related health outcomes at acceptable cost to patients and society.

Absent data on the accuracy and cost-effectiveness of screening or improved outcomes after the screening of asymptomatic individuals, it is difficult to endorse physician involvement in the enterprise.

Indeed, one might argue that the ethical stance should be to advocate against widespread use of full-body scans because the potential for harm seems to be stronger than the potential for beneficial health outcomes.

Army Lt. Col. Patrick G. O'Malley, MD, MPH, chief of general internal medicine, Walter Reed Medical Center, Washington, D.C.