A new blood test can detect lung cancer years before CT scan could, U.S. researchers have found.(File Photo)

    BEIJING, July 17 (Xinhuanet) -- A blood test can correctly predict non-small-cell lung cancer in blood samples taken from patients years before they are actually diagnosed with lung cancer, U.S. researchers reported in the latest edition of the Journal of Thoracic Oncology.

    Lung cancer is by far the biggest cancer killer globally. 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.

    "These data suggest antibody profiling could be a powerful tool for early detection when incorporated into a comprehensive screening strategy," the researchers at the University of Kentucky wrote in their report.

    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.

    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.

    In this study the researchers 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," the researchers wrote.  Enditem

    (Agencies)