WEDNESDAY, June 9, 2004 (HealthDayNews) -- Measuring the presence of DNA from a common virus in people with a type of head and neck cancer may help predict survival, new research suggests.
Virtually all nasopharyngeal tumors, which originate in an area in the back of the nose toward the base of the skull, contain Epstein-Barr virus (EBV), although scientists do not yet know why. Most people become infected with the virus at some point in their life, usually without ill effect. However, EBV can cause mononucleosis in some people.
Nasopharyngeal cancer itself is more common among Cantonese-speaking populations and is generally not amenable to surgery. It is treated instead with radiation, chemotherapy, or a combination of the two.
Researchers from Taiwan wanted to see if the DNA load of EBV correlated with how a patient responded to treatment and the likelihood of relapse and survival. Their report appears in the June 10 issue of the New England Journal of Medicine.
In people with nasopharyngeal cancer, tumor cells die and release their DNA, including the DNA of the Epstein-Barr virus, into the bloodstream, where it can be detected. These are not particles of virus, such as are measured in AIDS patients, but actual DNA. "In this case, they're not measuring particles at all. They're measuring naked DNA that was present as the DNA of the tumor cell," said Dr. Richard Ambinder, a professor of oncology at Johns Hopkins Singapore, who is studying the Epstein-Barr virus, particularly as it relates to Hodgkin's disease.
"The plasma is really the highway that the garbage from dead tumor cells is being transported in," Ambinder explained. If this "garbage" is present at all, it usually means that there are live tumor cells present somewhere else. This would make sense if a person had just had chemotherapy to kill off the tumor cells, but it could otherwise signal the presence of living tumor cells.
The study population consisted of 99 patients with stage III or IV nasopharyngeal cancer -- advanced stages, but with no evidence of spread at the time of the study. Participants received chemotherapy weekly for 10 weeks, followed by radiation. During that time, their blood was checked for the presence of Epstein-Barr DNA. These patients were compared to a control group comprised of healthy people and completely recovered patients.
DNA was found in 94 of the 99 patients but not in any of the cured or healthy individuals.
Generally speaking, patients with more advanced disease had more DNA. Also, patients who had had a relapse had higher DNA concentrations before treatment than those who did not end up having a relapse.
"There's a suggestion that you had a better prognosis with a lower viral DNA load than if you had a higher level and, also, recurrence was associated with a rise in DNA," said Dr. John A. Ridge, chief of the head and neck surgery section at Fox Chase Cancer Center in Philadelphia.
"Overall survival and relapse-free survival were significantly lower among patients with [higher] pre-treatment plasma concentrations," added Dr. Ralph Vance, national president of the American Cancer Society.
Experts were divided, however, on whether these results would translate into immediate benefits for patients.
"It's a very interesting study, but it's also a very small study," Vance said. "If it does work out after studying 500 patients, as a clinician, after giving chemo, radiation and maybe surgery, we could then get a virus load of zero. Then you could probably feel pretty confident that you had a complete response." It can be difficult with head and neck cancers to tell from an MRI or CT scan if someone is having a recurrence because of scar tissue. This test could eliminate that uncertainty.
"It would be nice if we had a very effective test to indicate who was likely to do well and might conceivably benefit from less aggressive treatment," Ridge added. "But we're a long way from doing that."
Others think the benefit may be more immediate.
In parts of Asia, however, the procedures already seem to be in place. "It's already being done in Hong Kong in a serious way and it looks like Taiwan is right there," Ambinder said. "I think in places where nasopharyngeal carcinoma is common and they have relatively advanced medicine, this has become sort of standard."
For more on nasopharyngeal cancer, visit the American Cancer Society.