Routine whole-body scans risk cancer

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Routine whole-body scans risk cancer

Reuters

Tuesday, 31 August 2004

 

 

 

Healthy people are exposing themselves to unnecessary risks if they have

routine whole-body CT scans, says new research (Image: U.S. FDA)

People who pay for whole-body CT scans in the hope of finding tumors at

their earliest stages may, ironically, be raising their overall risk of

cancer, doctors warned.

 

The scans are marketed as a way to catch cancer before symptoms begin, but

the radiation from the scans themselves could cause cancer, the researchers

said in the September issue of the journal Radiology.

 

The research relates to scans marketed directly to people to detect early

signs of diseases including heart disease, lung cancer or colon cancer.

 

These CT or computed tomography scans involve x-rays, but computer software

and multiple angles produce a higher-quality image than the traditional flat

x-ray.

 

The scans are not the same as magnetic resonance imaging or MRI scans, which

do not expose the body to radiation.

 

And the research relates specifically to whole-body CT scans for people

without symptoms rather than CT scans for people whose doctor recommends

them.

 

Radiation oncologist Professor David Brenner and colleagues at Columbia

University in New York said whole-body CT scans pack a considerable

radiation wallop.

 

" The radiation dose from a full-body CT scan is comparable to the doses

received by some of the atomic-bomb survivors from Hiroshima and Nagasaki,

where there is clear evidence of increased cancer risk, " Brenner said.

 

The researchers studied survivors who were exposed to low doses of radiation

from the bombs, not those who got the highest doses.

 

The dose from a single full-body CT was only slightly lower than the mean

dose experienced by some atomic bomb survivors, they said, and was nearly

100 times that of a typical screening mammogram.

 

A 45-year-old person who gets one full-body CT screening would have an

estimated lifetime cancer death risk of approximately 0.08%, which would

produce cancer in one in 1200 people, the researchers estimated.

 

But a 45-year-old who has annual full-body CT scans for 30 years would

accrue an estimated lifetime cancer mortality risk of about 1.9% or almost

one in 50.

 

The researchers noted that different CT scanners expose patients to

different doses of radiation, and so people are exposed to different risks.

 

Weighing up the risks and the benefits

 

Brenner said, unlike self-referred whole-body scans where the risks

outweighed the benefits, when doctors recommended scans, the potential

benefit outweighed the risks.

 

Another problem with the self-referred full-body scans, the researchers

said, was the number of people who had additional tests as a result of the

scans but who turned out not to have an underlying disease.

 

" Elective, full-body CT may provide false-positive findings when no disease

exists ... This typically involves more extensive testing, which is costly

and stressful, " Brenner said.

 

The Royal Australian and New Zealand College of Radiologists does not

believe there is sufficient scientific evidence to justify recommending

whole-body CT scans for screening when there are no symptoms or a family

history suggesting disease.

 

In the college's 2002 statement, available on its website, the college said

there is no evidence that whole-body scanning used this way is

cost-effective or effective in prolonging life.

 

The college was also concerned that this procedure would lead to the

discovery of numerous findings that would not ultimately affect patients'

health but would result in increased patient anxiety, unnecessary follow-up

examinations and treatments and wasted expense.

 

 

with ABC Science Online

 

 

 

Related Stories

Pregnant flyers warned of radiation, News in Science 10 Jun 2004

Virtual colonoscopy: not fool-proof yet, Health Minutes ABC Health Online 6

May 2004

Study spells out x-ray risk, not benefit, News in Science 30 Jan 2004

 

 

 

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