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NCI Begins Trial of Spiral CT vs X-rays as a Screening Test

NCI Begins Trial of Spiral CT vs X-rays as a Screening Test

BETHESDA,
Maryland—Researchers have begun accruing 50,000 patients for the National Lung
Screening Trial (NLST), the much-awaited comparison of the efficacy of spiral
CT scans and chest x-rays in reducing lung cancer mortality. Investigators in
the 8-year, National Cancer Institute-supported study expect to complete
enrollment within 2 years. Enrollment will be aided by a $5 million educational
campaign funded and organized by the American Cancer Society (ACS), and aimed
at encouraging current and former cigarette smokers to participate in the
trial.

"We estimate that about 169,000 men and women will be
diagnosed with lung cancer in 2002, and about 155,000 deaths will occur," said
co-principal investigator John K. Gohagan, PhD, chief of the NCI Early
Detection Research Group. He emphasized that the tests being studied are the
only accepted and proven screening tests for lung cancer that could reduce
mortality.

Thirty medical centers throughout the United States will
take part in the $200 million randomized, controlled study. Results from
earlier spiral CT studies, conducted by a collaboration of New York City
researchers and a group in Japan, have indicated that spiral CT, also known as
helical CT, can detect tumors much smaller than 1 cm. Chest x-rays can reveal
tumors as small as 1 to 2 cm in size. However, there is no scientific evidence
showing that either chest x-rays or spiral CT screening has a positive effect
on lung cancer mortality.

Despite this lack of mortality evidence, the potential for
finding lung cancer at a size that theoretically should increase a patient’s
chances of surviving the disease has led many present and past smokers to have
spiral CT scans. A number of specialized centers have opened to meet the
demand, which has disturbed oncologists and public health officials.

"In many instances, those individuals, in good faith, are
having screening tests done on the assumption that they are helping themselves
from a medical perspective," said Denise Aberle, MD, professor and chief of
thoracic imaging, UCLA, and the NLST’s other co-principal investigator.

"The reality is we don’t know that the screening test is
actually of benefit. We don’t know whether that test may actually expose them
to downstream complications of additional diagnostics, which have their own
morbidity and potential mortality that may do them more harm than the screening
test itself," she said.

NCI has sponsored three previous studies, which began in the
1970s, examining the use of chest x-rays and sputum cytology as potential
screening tests for lung cancer.

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