NEW YORKThe development of computers and diagnostic
platforms is facilitating mass screening for lung cancer not only with helical
CT but also with sputum cytology, according to Melvyn S. Tockman, MD, PhD,
professor of medicine and director, Program in Molecular Screening, H. Lee
Moffitt Cancer Center & Research Institute, University of South Florida,
Dr. Tockman sees detection of sputum molecular markers as being
complementary to CT findings. "Compared to helical CT, molecular airway
markers detect lung cancers at a complementary stage, clonal vs invasive, and
at complementary locations, central vs peripheral," he said at the 3rd
International Conference on Screening for Lung Cancer.
Sputum studies, Dr. Tockman added, also yield cell types not
usually seen in lesions detected on CT.
The Moffitt Cohort Study, he said, is using both sputum
cytology and helical CT lung scans. "The hypothesis is that we will
increase the percentage of stage I detected cancer threefold, from the standard
Florida cancer data system of 20% in stage I to 60%," he said.
For the clonal phase of cancer development, Dr. Tockman said,
the researchers will look at sputum specimens. "We’re going to
investigate transformed premalignant cells and clonal expansions at their
origin on the epithelial surface. We’re going to sample that transformation
and progression through exfoliated cells prior to clinical malignancy."
In contrast, he said, for invasive lesions or lesions large
enough to already have their own blood supply, "we’ll take a look at
Sputum specimens are being collected annually from 1,100
individuals in the Moffitt study and examined for morphology and other markers
of preneoplasia, including upregulated gene expression of the hnRNPA2/B1
protein. Eligibility criteria include age 45 years or older, a history of 30
pack-years of smoking, and pulmonary obstruction as evidenced by an FEV1 :FVC
ratio of 70% or less.
Preliminary findings, Dr. Tockman reported, include a
prevalence (positive scans) of 34%. "We’re seeing somewhat more cases of
cancer than expected," he said. The incidence was 1.9%compared with
1.1% in the Early Lung Cancer Action Project (ELCAP) studywith 25% being
stage I. Three persons had stage IV cancer when screened.
Noting that 80% of the cancers detected in ELCAP were stage I,
Dr. Tockman said, "I suspect that much of the difference may be due to the
fact that this younger population has more aggressive tumors." ELCAP
required subjects to be at least 60 years of age.
Since nearly all smokers start the habit before age 20, he
said, cancers detected after age 60 may grow more slowly than those occurring
in younger persons.