WEDNESDAY, June 29 (HealthDay News) -- Routinely screening
longtime smokers and former heavy smokers for lung cancer using CT
scans can cut the death rate by 20 percent compared to those
screened by chest X-ray, according to a major U.S. government
The National Lung Screening Trial included more than 53,000
current and former heavy smokers aged 55 to 74 who were randomly
chosen to undergo either a "low-dose helical CT" scan or a chest
X-ray once a year for three years.
Those results, which showed that those who got the CT scans were
20 percent less likely to die than those who received X-rays alone,
were initially published in the journal
Radiology in November 2010.
The new study, published online July 29 in the
New England Journal of Medicine, offers a fuller analysis of the data from the trial, which was funded by the U.S. National Cancer Institute. Detecting lung tumors earlier offers patients the opportunity for earlier treatment.
The data showed that over the course of three years, about 24
percent of the low-dose helical CT screens were positive, while
just under 7 percent of the chest X-rays came back positive,
meaning there was a suspicious lesion (tissue abnormality).
Helical CT, also called a "spiral" CT scan, provides a more
complete picture of the chest than an X-ray, experts said. While an
X-ray is a single image in which anatomical structures overlap one
another, a spiral CT takes images of multiple layers of the lungs
to create a three-dimensional image.
About 81 percent of the CT scan patients needed follow-up
imaging to determine if the suspicious lesion was cancer. But only
about 2.2 percent needed a biopsy of the lung tissue, while another
3.3 percent needed a broncoscopy, in which a tube is threaded down
into the airway.
"We're very happy with that. We think that means that most of these positive examinations can be followed up with imaging, not an invasive procedure," said Dr. Christine D. Berg, study co-investigator and acting deputy director of the division of cancer prevention at the National Cancer Institute.
The vast majority of positive screens were "false positives" --
96.4 percent of the CT scans and 94.5 percent of X-rays. False
positive means the screening test spots an abnormality, but it
turns out not to be cancerous.
Instead, most of the abnormalities turned out to be lymph nodes
or inflamed tissues, such as scarring from prior infections.
During about six years of follow up, there were 247 deaths from
lung cancer for every 100,000 person-years in the low-dose CT group
and 309 deaths per 100,000 person-years in the X-ray group, a 20
"It is great news. We know that individuals who smoke are at increased risk of lung cancer, but we've never had any screening to offer them to catch the disease earlier when it's more treatable," said Dr. Therese Bevers, medical director of the Cancer Prevention Center at the M.D. Anderson Cancer Center in Houston. "Now we're able to offer this high-risk population a screening test that can reduce their chances of dying from this disease."
Study participants included people who'd smoked at least 30
"pack years" -- that means, current or former smokers who'd smoked
an average of one pack a day for at least 30 years, or two packs a
day for at least 15 years.
The patients in the study who survived lung cancer did so
because it was caught early by the screening test, before it had
spread elsewhere in the body, and when it could still be surgically
removed, Berg said.
CT scans were effective in spotting both adenocarcinomas, which
begin in cells that line the lungs, and squamous cell carcinomas,
which arise from the thin, flat fish-scale-like cells that line
passages of the respiratory tract. CT scans were not as good at the
early detection of small cell lung cancer, an aggressive and less
common type of lung cancer, Berg said. (X-rays were also less
likely to spot this type of cancer.)
Still, questions remain, noted Dr. Harold Sox, a professor
emeritus of medicine at Dartmouth Medical School who wrote an
accompanying editorial in the journal. According to the National
Cancer Institute, spiral CTs cost from $300 to $1,000, which means
insurers and policy-makers have to consider who is going to pay for
it, and who should receive one.
The trial also found that about 1 percent of people who
underwent surgery to remove a cancerous tumor died. Nationwide,
that number is closer to 4 percent, Sox said, a rate of
post-surgical complications that has the potential to erase some of
the life-saving gains from the early detection.
U.S. National Cancer Institute has more on spiral
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