Lung Cancer CT Scans No Help?
CT Scans for Smokers Up Risks, Don't Cut Lung Cancer Deaths, Study Shows
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Big Risks From CT Screening for Lung Cancer
It's already been shown that using chest X-rays to screen symptom-free
smokers for lung cancer does not result in fewer lung cancer deaths.
But researchers have been hoping CT scans would work better.
CT stands for computed tomography. It's a sophisticated, computer-assisted
technique that gives doctors a much better look at an organ than an X-ray.
When used for screening, doctors set the CT scan to deliver only low-dose
radiation. But that's still seven or eight times the radiation you'd get from
an X-ray, Bach says.
"When abnormalities are found on low-dose CT scans -- which happens in
15% to 50% of smokers -- more CT scans are done, and those are full-dose
scans," he says. "And 12% of these people end up having biopsies for
tumors that turn out to be benign -- because the actual cancer rate is south of
Also, Bach says that many of the 1% of patients who seem to have malignant
tumors actually have only benign growths that, if undetected, would never
become deadly tumors. But because doctors can't say for sure which early
cancers will turn deadly, nearly all of them mean lung surgery.
In earlier studies, X-ray screening for lung cancer didn't just fail to
prevent lung cancer death. It also increased the rate of lung cancer diagnosis
by 50%. Bach says CT scans increase the rate of diagnosis by 300% -- and lead
to a tenfold increase in the number of lung surgeries. Yet his data suggest no
lives are saved.
"This means we are exposing patients to radiation, biopsies, and
surgeries with highly uncertain clinical benefits," he says.
And then there is the anxiety caused by having an abnormality found.
"So say you have an abnormal finding on CT, and your doctor says, 'Oh,
we don't know what it is, come back in six months,'" Bach says. "If the
CT scan screening were effective, and we were going to save lives, we could
work with patients on managing this anxiety-creating test. But we should not
subject people to such tests when we have no objective evidence it will help
But what about the relief you might feel if your CT scan is normal? Bach
says this is false reassurance.
"If you don't show positive on a screening CT scan, there is no
guarantee you won't die of lung cancer," he says. "I don't want people
to get the idea that we can rule out cancer."