Early detection
of lung cancer may be possible with combination of spiral computed tomography
and positron emission tomography
Early detection of lung cancer may be possible with
a combination of spiral computed tomography and positron emission tomographic
scanning, according to preliminary study results reported in the August
23rd issue of the Lancet. The authors suggest that future randomized trials
may assess the usefulness of the techniques for widespread population-level
screening.
The authors of the European study note that low-dose
spiral computed tomography of the chest effectively detects early-stage
lung cancer in high-risk individuals; however the high detection rate of
benign lesions has been an obstacle to a trial of large-scale screening
programs.
In the current study, Ugo Pastorino, MD, Peter Boyle,
MD, and their colleagues investigated the effectiveness of yearly spiral
computed tomographic scanning and selective use of positron emission scanning
(to increase the accuracy of initial findings) in a large population of
high-risk volunteers. Over 1000 heavy smokers (minimum consumption 26 cigarettes
per day for 37 years) aged 50 years or older underwent annual low-dose
spiral computed tomography, with or without positron emission tomography,
for 5 years. Lesions up to 5 mm in size were deemed non-suspicious, and
screening was repeated after another year.
By the second year of assessment, 22 cases of lung
cancer had been diagnosed (11 at baseline, 11 at the beginning of year
2). A total of 440 lung lesions were identified in 298 participants (29
percent), and 95 were recalled for high-resolution contrast computed tomography.
Positron emission tomographic scans were positive in 18 of 20 of the identified
cancer cases. Removal of malignant tissue was achieved in 95 percent of
lung cancer tumors.
Pastorino commented, "We have shown that low-dose
spiral computed tomography combined with selective use of positron emission
tomography can effectively detect early lung cancer. A more conservative
approach to very small computed tomography-detected nodules is justified,
and lesions up to 5 mm can be followed up at 12 months without major risks
of progression. Although prospective randomized trials are the proper instrument
with which to measure the ultimate outcome of any screening policy, pilot
studies addressing specific technical issues and methods are of fundamental
importance in a phase of accelerated development of imaging and molecular
technology, to design the optimum protocol to be tested in large-scale
trials."
In an accompanying Commentary, Stefan Diederich,
MD, wrote, "The study by Pastorino and colleagues adds an important
aspect to the field of lung cancer screening with low-dose computed tomography
- that is, simplification of the diagnostic algorithm for nodule classification.
More data are required to define the ideal algorithm. Furthermore, prospective
randomized trials are underway to analyze whether regular low-dose computed
tomography can, in fact, reduce mortality from lung cancer."
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