NEW YORKScreening of smokers with helical (spiral)
low-dose computed tomography (CT) is more likely than chest x-rays to
find malignant tumors, and the tumors are substantially smaller
than those detected on chest radiography, said Claudia I.
Henschke, MD, of New York Presbyterian Hospital-Weill Cornell Medical Center.
Dr. Henschke and her colleagues at Cornell, New York University, and
McGill University reported baseline results of the Early Lung Cancer
Action Project (ELCAP), a study designed to evaluate baseline and
annual repeat screening by low-radiation-dose CT in people at high
risk of lung cancer.
The study has enrolled 1,000 symptom-free volunteers, aged 60 or
older, with at least 10 pack-years of cigarette smoking and no
previous cancer. At baseline, low-dose CT detected 233 noncalcified
nodules, compared with 68 detected by chest x-ray.
Subjects with noncalcified nodules then underwent standard-dose
diagnostic chest CT. Based on these findings, the researchers used an
algorithm to determine the need for further diagnostic investigation.
Biopsies were subsequently done on 28 of the 233 subjects with
noncalcified nodules. All but one proved malignant. Another
three individuals underwent biopsy against the ELCAP recommendations;
all had benign noncal-cified nodules, Dr. Henschke said.
Further, 23 of the tumors found by low-dose CT were stage I, and all
27 tumors detected by CT were resectable. In contrast, chest x-ray
found only four stage I tumors (Lancet 34:99-105, 1999).
Although we still need longer-term follow-up of our baseline
CT-detected cases of malignant disease, the high frequency of those
in stage I is a strong indication that the cure rate of CT-detected
disease is much higher than the current overall US cure rate of about
12%, Dr. Henschke said.
She noted that low-dose screening CT can be done in 20 seconds and
does not require IV contrast injection. The cost is only
slightly higher than that of a chest x-ray, she said, adding
that if demand for CT screening increases, cost will fall.
In an interview, Barnett Kramer, MD, deputy director of the NCIs
Division of Cancer Prevention, called the results an important
first step in evaluating an emerging technology for lung cancer
screening . . . although the study was not designed to definitively
prove its value in saving lives. The NCI plans to fund studies
of low-dose helical CT screening with lung cancer mortality as an
endpoint, he said. He cautioned that the same sort of enthusiasm
surrounded chest x-ray screening in the early 1970s, but when
put to definitive testing, it did not show a survival benefit.