A controversial new study offers the strongest evidence yet that screening
smokers for lung cancer with computerized chest scans can save lives, much as
mammograms do for women with breast cancer.
Doctors have long had doubts that early detection of tumors could improve
survival, and also feared that screening would lead to too many false alarms and
unnecessary biopsies. Scans are not now recommended, but many smokers have been
paying for them on their own for their peace of mind.
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A controversial new study reported in Thursday's New England
Journal of Medicine offers the strongest evidence yet that screening
smokers for lung cancer with computerized chest scans can save lives.
[AP]
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The new study strongly suggests there is a survival benefit. But it does not
prove the point, because it lacked a comparison group, many scientists say.
In the study, people whose early lung tumors were detected by CT scans and
promptly removed had an estimated 10-year survival rate of 92 percent -
much better than the roughly 70 percent who typically survive, and far better
than the dismal 5 percent who make it that long after the disease has spread
beyond the lungs.
"It gives us greater confidence that screening may really offer advantages in
saving lives from lung cancer," said Dr. Robert Smith, director of screening at
the American Cancer Society, which was among more than two dozen groups that
funded the study.
Even though the study lacked a comparison group, he said, "it's highly
unlikely that this completely invalidates the observation of a favorable benefit
from early diagnosis."
Lung cancer is the world's top cancer killer. About 174,470 Americans and 1
million people worldwide will be diagnosed with it this year. The vast majority
will die, largely because the disease is found too late for treatment to do much
good. Only 16 percent of cases in the United States are detected in Stage 1,
when tumors are still confined to the lung.
Studies in the 1970s found that screening smokers with regular X-rays did not
improve lung cancer survival, and such efforts were largely abandoned until the
1990s, when CT scans were developed.
These sophisticated X-rays produce images of the lungs from many angles and
can reveal pea-size growths long before they produce symptoms. Interest in the
scans rose in 1999, when Dr. Claudia Henschke of New York-Presbyterian
Hospital/Weill Cornell Medical Center published a landmark study showing that
they found far more tumors than conventional X-rays did.
Her new study, reported in Thursday's New England Journal of Medicine,
extends these results to a larger group of people and reports on survival.
Dozens of researchers around the world screened 31,567 people at high risk of
lung cancer because they were current or former smokers or had been exposed to a
lot of secondhand smoke.
Participants were initially screened between 1993 and 2005, and the vast
majority came back for repeated screenings about a year later. Thirteen percent
of those who were initially screened and 5 percent who had repeated screenings
had suspicious spots that required further testing. Biopsies were performed on
535 patients; 484 were diagnosed with lung cancer, including 412 in the early
stage. Most had surgery or chemotherapy, and eight were untreated.
Researchers then calculated survival probability using a common statistical
tool. The estimated 10-year survival rate, regardless of when the cancer was
diagnosed or the type of treatment, was 80 percent.
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