Blood Test Detects Early Lung Cancer
Positive Test for Blood Protein Signals High Cancer Risk
Sept. 18, 2007 -- A new blood test promises to detect lung cancer at its earliest, most curable stages.
The test is under development by Panacea Pharmaceuticals, Gaithersburg, Md. It detects a recently discovered protein called HAAH. People with at least 20 different kinds of cancer -- including lung cancer -- have much higher than normal HAAH levels in their blood.
The test does not prove that a person has cancer. But it does identify people who need additional, more definitive tests, says Panacea research scientist Mark Semenuk.
"The important thing is that we can pick up even stage I lung cancer," Semenuk tells WebMD. "To diagnose lung cancer really early provides the opportunity for curative treatment. Unfortunately, lungcancer does not cause symptoms until fairly late in the disease process."
Semenuk presented studies of the new lung cancer test to this week's American Association for Cancer Research second international conference on Molecular Diagnostics in Cancer Therapeutic Development, held Sept. 17-20 in Atlanta.
In their first study, Semenuk and colleagues obtained 160 blood samples from 160 patients at all four stages of lung cancer and from 93 people who did not have lung cancer.
The HAAH test was positive in 99% of the lung cancer samples but was nearly undetectable in people without cancer. This study allowed the researchers to set an HAAH cutoff level -- 3 ng/mL (nanograms/milliliter) -- that maximizes the number of cancers detected while minimizing the number of false-positive test results.
In a second study, the researchers tested how well the HAAH test could tell people with various stages of lung cancer from smokers without lung cancer. Previous blood tests for lung cancer have been unable to differentiate smokers -- who are at very high risk of lung cancer -- from patients with early-stage lung cancer.
The result: Average HAAH levels were about the same for patients at all four stages of lung cancer, ranging from 16 ng/mL to 22 ng/mL. Average HAAH levels for smokers not known to have cancer were zero. However, about 10% of the smokers tested positive for elevated HAAH levels.