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Yet another high-tech
medical intervention fails to show benefit
Screening smokers several times a year with chest
X-rays does not reduce their odds of dying from lung cancer and may lead
some people to undergo unnecessary treatment for lung tumors that would
never have been fatal, new research suggests. The findings call into question
the wisdom of using a relatively new, more powerful lung screening technique
to detect lung cancer.
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Researchers at the National Cancer Institute
(NCI) assigned more than 9,000 male smokers to undergo a chest X-ray
and sputum cytology (examining phlegm under the microscope to detect
cancer cells) three times a year for 6 years or were advised to have
the same tests only once a year.
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The first participants were enrolled in 1971,
and by 1983, men who underwent frequent screening were no less likely
to die from lung cancer than other men.
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Even after an average of more than 20 years
of follow-up, the results were still the same.
"We found no reduction in lung cancer mortality,"
said one of the researchers in comments to Reuters Health. As a matter
of fact, in the intense-screening group, 337 men died from lung cancer,
compared with only 303 of the men who were advised to be screened just
once a year.
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According to the authors, the chest x-rays seem
to detect some very small or slow-growing lung tumors that may never
threaten lives.
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Additionally, procedures and surgery to evaluate
or remove these detected growths can be risky.
Dr. Pamela M. Marcus, of the NCI said that the idea
that some lung tumors may be present for years without ever causing symptoms
is "pretty heretical," towards the current beliefs. The results
of the study should also give doctors second thoughts about using a powerful
new imaging test, known as spiral computed tomography (CT), to screen
for lung cancer. Although it may be capable of detecting lung lesions
in their early stages, there is no proof that the test can reduce lung-cancer
deaths.
"It hasn't been shown that spiral CT reduces
lung cancer mortality," Dr. Marcus said. "We shouldn't be jumping
on the spiral CT bandwagon yet."
Journal of the National
Cancer Institute August 16, 2000; 92.
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