Lung Cancer Blood Test Possible Following Biomarker Discovery
Lung cancer is the number one cause of cancer death in the United States, claiming about 157,000 people each year. Researchers have now discovered a biomarker that could lead to a blood test capable of detecting the disease up to two years before the tumor is found.
New lung cancer diagnostic tests are needed
More than 222,000 new cases of lung cancer were diagnosed in 2010, according to National Cancer Institute estimates. Current screening methods for lung cancer include chest x-rays and sputum cytology, which involves examining a sputum sample under a microscope to check for cancer cells.
Clinicians can also use more sophisticated imaging tests, including computed tomography (CT), positron emission tomography (PET), and magnetic resonance imaging (MRI), which can reveal cancerous growths not seen using conventional chest x-rays. However, a biopsy is still the only way to make a definitive diagnosis of lung cancer.
According to research recently published in the Proceedings of the National Academy of Sciences, abnormal patterns of microRNA (miRNA) have been identified in the blood of individuals who have lung cancer. This finding is significant, says Dr. Carlo M. Croce, professor of molecular virology, immunology and medical genetics, and director of the Human Cancer Genetics program, because it “showed that it might be possible to use these patterns to detect lung cancer in a blood sample.”
Even more important is that the abnormal miRNA were in the blood long before spiral CT scans detected the tumors, “suggesting they might have strong predictive, diagnostic and prognostic potential,” according to Croce.
To arrive at their findings, Croce and his colleagues collected tissue samples from patients who had participated in a clinical trial that used spiral CT scans to screen for lung cancer. All the 1,035 participants were 50 years or older, had smoked at least one pack of cigarettes a day for at least 20 years, and had undergone a CT scan annually for five years, along with providing blood, sputum, and urine samples.
First the researchers evaluated 28 tumor samples and 24 normal lung tissue samples for miRNA and found miRNAs that could discriminate between normal lung tissue and cancerous tissue. They also identified miRNA patterns that differentiated fast growing tumors and poor disease-free survival.
When the researchers analyzed blood samples collected more than a year before a patient’s lung cancer was identified using CT, they found a signature of 15 miRNAs that could identify 18 of 20 patients whose lung cancer was later detected using spiral CT.
The researchers then used the signature in another set of blood samples from a different lung cancer study, and the signature identified 12 of 15 patients whose cancer was detected more than a year later using spiral CT. Overall, the investigators estimated that the miRNA signature was identifiable in blood more than two years—28 months—before spiral CT detected the cancer.
Croce noted that the goal of their study was to “identify biomarkers that could predict tumor development and prognosis to improve lung cancer diagnosis and treatment.” The study’s findings “strengthen the observation that circulating miRNA in plasma is detectable well before clinical disease detection,” and they could lead to a blood test for lung cancer.
Ohio State University