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Whole-body CT scans can increase cancer risk

Los Angeles Times, Aug. 31, 2004, 4:09PM

Whole-body CT scans, long controversial because of doubts about their effectiveness in finding hidden disease, can significantly increase the recipient's risk of developing cancer, according to a new study.

The radiation from a single whole-body scan is equal to that from 100 mammograms and is similar to that received by survivors of the atomic bombing of Hiroshima and Nagasaki -- about 1.5 miles from the explosion -- according to radiation biologist David J. Brenner of Columbia University

The radiation from one scan is enough to produce one tumor in every 1,200 people who undergo the procedure, reported Brenner and co-author Carl D. Elliston of Columbia in the journal Radiology. For those who have annual scans, the risk goes as high as one tumor in every 50 people, they said.

"The risks for a single scan are not huge," Brenner said. "But if you have them repeatedly, the risk starts to build up quite a lot and becomes quite significant."

Brenner cautioned that his results apply only to healthy individuals who choose to receive the scans. "The risk-benefit equation changes dramatically for adults who are referred for CT exams for medical diagnosis," he said. "Diagnostic benefits far outweigh the risks."

CT scans, short for computerized tomography, are produced with X-rays using an X-ray source that travels from head to toe, spiraling around the body. Powerful computer programs integrate the data to produce threedimensional images of the body in high detail.

The tests, which cost $800 to $1,500, are heavily advertised, with slogans touting the device's ability to detect hidden diseases. The most commonly sought diseases are cancers, especially lung cancers.

Whole-body CT scans have surged in popularity since they were first used in the mid-1990s, converting a procedure once reserved for the seriously ill to a commonplace screening technique that reached a peak of 32 million scans in 2002.

But the total number of scans has been declining recently because of the slow economy, according to Bruce Friedman of Heart Check America, one of the largest centers in Los Angeles.

Friedman said he thinks the study means "it is worth talking about the risks as well as the benefits." He doesn't think the study is a reason for people to get scared, but still recommends that they be cautious.

Even though 15 percent of his business is for whole-body scans, Friedman said, "I have never had a full-body scan, and I wouldn't recommend one to anyone I know who doesn't have a reason to think they are sick."

Most major health organizations, including the Food and Drug Administration, the American Cancer Society, the Environmental Protection Agency and the American College of Radiology, recommend against elective whole-body scans.

An FDA statement, for example, says that the agency "knows of no data demonstrating that whole-body CT screening is effective in detecting any particular disease early enough for the disease to be managed, treated, or cured and advantageously spare a person at least some of the detriment associated with serious illness or premature death."

Similarly, the Health Physics Society, a major organization of radiologists, says that "no medical use of radiation should be employed unless there is a clear medical benefit," which is not the case for whole-body CT scanning. "Generally, people with no symptoms have a very low prevalence of disease."

For the same reason, most insurance companies do not pay for the scans.

Texas and Pennsylvania have banned the scans unless the patient is referred by a physician, and other states are thought to be considering taking similar action.

No one has been documented to have a tumor caused by whole-body CT scans -- at least in part because the technique has been around for only a few years and radiation-induced tumors take decades to develop.

The analysis used data from atomic-bomb survivors, Brenner said, because they have been studied for more than 50 years, long enough for most potential cancers to occur.

Brenner and Elliston found that one CT scan exposes the recipient to about 12 millisieverts of radiation. Atomic-bomb survivors in the low-dose range received 5 to 100 millisieverts and showed a statistically significant increase in risk of solid tumors, such as cancers of the lung and digestive system.

Previous controversies about whole-body scans have centered on their great sensitivity, which reveals many abnormalities that ultimately prove to be harmless, but which must be studied further, often with invasive techniques.

A 2002 study by Dr. Giovanna Casola and her colleagues at the University of California, San Diego found that about a third of patients receiving the whole-body scans required follow-up exams. About 10 percent of the patients were told that they might have a tumor, but only 1 percent of all patients were found to have a life-threatening condition.

Casola said that the new study "obviously reinforces" concerns about the procedure.

"The tests are failing, and failing on a high level, to show that they are worthwhile," said Dr. Barry Pressman of Cedars-Sinai Medical Center in Los Angeles. "There is no clear proof that they are beneficial and more reason to think they are harmful."

And since at least the subject of CT scans bears repeating, here is a similar article warning about Whole Body CT Scans and cancer: Repeated Body CT Scans Boost Cancer Risk
Screening tool has risks while benefits are unclear

By Steven Reinberg
HealthDay Reporter

TUESDAY, Aug. 31 (HealthDayNews) -- Body scans, a screening tool that many have touted as a way to catch cancer early, may actually increase the risk of disease if used too often.

The chances of dying from cancer caused by radiation from a full-body CT scan is low when done only once, but a new study finds the danger increases dramatically if the scan is performed every year or two.

These scans are an elective procedure that has become increasingly popular, and as more seemingly healthy people get them, researchers have become concerned about the potential risk.

"CT scans, by their nature, produce high radiation doses," explained lead researcher David J. Brenner, a professor of radiation oncology and public health at Columbia University Medical Center.

In terms of benefits, Brenner said there have not been any studies yet that have showed longevity or health is improved by having a scan or a series of scans.

Brenner and his colleague, Carl D. Elliston, wanted to find out the risk for a fatal cancer caused by a full-body CT scan. The researchers knew the radiation dose from a full-body CT scan is similar to the doses of radiation received by some survivors of the atomic bombs at Hiroshima and Nagasaki, Japan, during World War II. They also knew those survivors faced an increased cancer risk.

Using that data, the researchers calculated the risk of developing a fatal cancer from the radiation used in a full-body CT scan. Brenner added that older people tolerate radiation better.

The study appears in the September issue of Radiology.

For someone aged 45, the risk of developing a fatal cancer from a single full-body CT scan is about one in 1,200, "meaning that if 1,200 people had one scan, you might expect one of them to die of a radiation-induced cancer, which is not a huge risk," Brenner said.

However, if you have a scan every year or every couple of years, the radiation dose accumulates, and so does the risk, he said. "A 45-year-old who has one of these scans every year for 30 years, the risk is one in 50," he added.

"There you have a very substantial risk, so the benefit would have to be more than that to justify using this procedure," Brenner said. "And right now, we don't have evidence of the benefits."

"It's probably premature to consider having these tests until we really understand the benefits better, knowing what the risks are. It's a questionable decision to make at this point," Brenner said.

Another expert also urged caution.

"Whole-body CT scans are not recommended because we do not have evidence that they confer net benefit. This paper by Brenner is important for highlighting the potential harm," said Dr. David L. Katz, an associate clinical professor of public health and director of the Prevention Research Center at Yale University School of Medicine.

"Why would you voluntarily have a test not known to confer benefit, pay for it, and incur a cancer risk some 10,000 times greater than that associated with dioxin?" he added.

Katz noted that high-end medical businesses are making money by peddling such technology with very convincing advertisements.

"Confer with a trusted health-care provider about what tests to have and what tests to avoid," Katz said. "When it comes to whole-body CT scans, step away from the radiation, and your checkbook, and you'll be much better off," he advised.

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