More Cancer Risk Seen in Full-Body CT Scans
The radiation from one exam is equal to that in some atomic-bomb
survivors. But for the ill, diagnostic benefits outweigh the
August 31, 2004
By Thomas H. Maugh II and Daniel Costello, Times Staff
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 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
bombings of Hiroshima and Nagasaki, Japan --- about 1 1/2 miles
from the explosions --- according to radiation biologist David J.
Brenner of Columbia University.
The radiation from one scan is enough to produce a tumor in every
1,200 people who undergo the procedure, reported Brenner and coauthor
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 applied only to healthy
individuals who chose 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
X-ray source that travels from head to toe, spiraling around the
body. Powerful computer programs integrate the data to produce
three-dimensional images of the body in high detail.
The tests, which cost $800 to $1,500, are heavily advertised,
slogans touting the device's ability to detect hidden diseases. The
most commonly sought diseases are cancers, especially lung cancer.
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.
Southern California has been the nexus of the growth, with as
30% of the nation's screening centers located in this area. Several
have closed in the last year, however, because the market became
The total number of scans also has been declining because of the slow
economy, according to Bruce Friedman of Heart Check America, one of
the largest centers in Los Angeles.
Friedman said he thought that the study meant that "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 he recommends
Even though 15% 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
Many health-related agencies and 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 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
Texas and Pennsylvania have banned the scans unless the patient is
referred by a physician, and other states are thought to be
considering similar actions. Major medical centers including
Cedars-Sinai also require a physician's referral.
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
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.
They calculated the highest risk --- one tumor per 50 people --- for
patients who received annual scans for 30 years beginning at age
Previous controversies about whole-body scans have centered on their
sensitivity, which reveals many abnormalities that prove to be
harmless, but which must be studied further, often with invasive
A 2002 study by Dr. Giovanna Casola and her colleagues at UC San
Diego found that about a third of patients receiving the whole-body
scans required follow-up exams. About 10% of the patients were told
that they could have a tumor, but only 1% of all patients were found
to have a life-threatening condition.
Casola says that the new study "obviously reinforces" concerns about
"The tests are failing, and failing on a high level, to show that
they are worthwhile," Dr. Barry Pressman of Cedars-Sinai said. "There
is no clear proof that they are beneficial, and more reason to think
they are harmful."