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Blood test may find early lung cancer

July 16, 2006 - 9:11PM

A blood test that looks for the body's own immune response to tumours may
provide an easy way to find lung cancer in patients long before an X-ray
or CT scan could, US researchers report.

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 company 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 per cent.

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.

Special X-rays known as computed tomography or CT scans can find lung
cancer tumours, 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 tumours.

When they tested it in people who were being treated for lung cancer, it
correctly identified 90 per cent 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.