Test will be most useful in China, other parts of Asia, and North Africa where disease is more common
By Dennis Thompson
WEDNESDAY, Aug. 9, 2017 (HealthDay News) -- A new DNA blood test can catch a rare but deadly form of cancer that occurs in the sinuses, researchers report.
The test, which looks for DNA evidence of Epstein-Barr virus in blood samples, was 97 percent accurate at detecting the presence of nasopharyngeal cancer, according to the results of a clinical trial.
"I believe that the test is technologically ready for use for screening nasopharyngeal cancer in high-risk areas like Hong Kong," said senior researcher Dennis Lo. He's an associate dean of research and director of the Li Ka Shing Institute of Health Sciences with the Chinese University of Hong Kong.
The nasopharynx is the upper part of the throat that lies behind the nose, just above the soft part of the roof of the mouth and just behind the nasal passages, according to the American Cancer Society (ACS). It serves as a passageway for air between the nose and the throat.
Nasopharyngeal cancer is relatively rare, with less than one case for every 100,000 people in the United States and many other parts of the world, the American Cancer Society (ACS) says.
However, it is much more common in southern China and other parts of Asia and North Africa, making a test for early detection an important way to potentially save lives there, according to the ACS.
Nasopharyngeal cancer is closely related to the Epstein-Barr virus, a member of the herpes family, Lo explained.
"The Epstein-Barr virus genome can be found in more than 99 percent of tumor cells of nasopharyngeal cancer," Lo said. "It is believed that the virus is one of the causative factors for this cancer."
Based on this, Lo and his team developed a test to detect fragments of Epstein-Barr virus contained in tumor DNA that's released into the bloodstream as cancer cells die in a patient's body.
Test screening of more than 20,000 people detected Epstein-Barr viral fragments in more than 1,100 people, or about 5.5 percent. Of those, 309 had persistent positive results when tested repeatedly, the researchers found.
The DNA test wound up accurately detecting nasopharyngeal cancer 97 percent of the time. It accurately ruled out healthy people 98 percent of the time, study results showed.
The study was published in the Aug. 10 issue of the New England Journal of Medicine.
Dr. Richard Ambinder is a professor of oncology with the Johns Hopkins School of Medicine in Baltimore. He said, "By surveying the blood and looking for the fragments of the viral DNA, you could pick out people who needed a more careful look to see if they had an early cancer, and very often they found that they did."
Ambinder said the test will be of greatest value in Asian countries, and likely will not be pursued in the United States.
"We don't have the same incidence of nasopharyngeal cancer that Hong Kong and southern China have, so I don't have any idea whether someone is pushing for approval here," Ambinder said. "I don't think it's going to be high on anyone's priority list as a screen."
But this new report does point to new ways in which other virus-related cancers can be identified early, said Ambinder, who wrote an editorial accompanying the study.
"What's leaking out from the tumor cells here is tumor DNA that includes with it viral DNA," Ambinder said. "There's a lot of interest and progress made in diagnosing other tumors by the presence of tumor DNA in blood. There are some things about finding the viral DNA that make it a little easier to find," he added.
"I expect that there are a lot of cancers that we're going to be able to diagnose by the presence of these fragments of DNA," Ambinder continued. "This is only the beginning, but it wouldn't surprise me at all if this applied to many common cancers."
For more about nasopharyngeal cancer, visit the American Cancer Society.
SOURCES: Dennis Lo, F.R.S., associate dean of research and director, Li Ka Shing Institute of Health Sciences with the Chinese University of Hong Kong; Richard Ambinder, M.D., Ph.D., professor of oncology, Johns Hopkins School of Medicine, Baltimore; Aug. 10, 2017, New England Journal of Medicine
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