A blood test that looks for the body's own immune
response to tumors may provide an easy way to find
lung cancer in patients long before an X-ray or CT
scan could, U.S. researchers reported.
The test correctly predicted non-small-cell lung cancer
in blood samples taken from patients years before
they were actually diagnosed with lung cancer, the
researchers reported.
If the test's reliability can be confirmed, it might
become the first new blood screen for any cancer since
the prostate specific antigen or PSA test. The test
is licensed to privately held Rockville, Maryland-based
20/20 GeneSystems Inc.
"These data suggest antibody profiling could be a
powerful tool for early detection when incorporated
into a comprehensive screening strategy," the researchers
wrote in their report, published in the Journal of
Thoracic Oncology.
Non-small-cell lung cancer is the most common type
of lung cancer, and has an average five-year survival
rate of only 40 percent.
Lung cancer is by far the biggest cancer killer globally.
Each year 10 million people are diagnosed with it,
according to the Global Lung Cancer Coalition, and
half of all patients die within a year of diagnosis.
It kills more than 160,000 people annually in the
United States alone.
Special X-rays known as computed tomography or CT
scans can find lung cancer tumors, but they have a
high rate of false positives -- meaning many people
have to undergo a painful biopsy to get a piece of
a suspicious lump out of the lung, only to find out
it was not cancerous after all.
By the time people have symptoms of lung cancer,
it is usually too late to save them.
Li Zhong and colleagues at the University of Kentucky
developed a test that looks for certain proteins the
body makes in response to very early lung tumors.
When they tested it in people who were being treated
for lung cancer, it correctly identified 90 percent
of cases, and with very few false positives in samples
taken from people who did not have lung cancer.
They went back and tested blood samples taken from
some of the lung cancer patients years before they
were diagnosed. The test found cancer in four out
of seven samples taken a year before diagnoses, and
in all 18 samples taken two, three and four years
earlier.
"Based on doubling times, a lung cancer can be present
three to five years before reaching the conventional
size limits of radiographic detection," Zhong's team
wrote.
