Common Virus Found To Increase Cancer Risk

Newsweek

4 days ago

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Those who have a specific antibody that is produced following infection from a common virus may be at greater risk of developing certain cancers, a new study from the International Agency for Research on Cancer (IARC) has found.
Individuals who test positive for Epstein–Barr virus (EBV) capsid antigen (VCA-IgA) antibodies were found to have a higher risk of developing cancers such as lung cancer, liver cancer, nasopharyngeal carcinoma and lymphoma, according to a study shared by IARC with Newsweek.
Newsweek has contacted the Centers for Disease Control and Prevention (CDC) and the Department of Health and Human Services (HHS) via email for comment.
What Is Epstein-Barr Virus?
The Epstein-Barr virus is one of the most common and persistent human viruses in the world, according to the CDC, and is member of the herpes virus family. EBV infects approximately 95 percent of the global population, the IARC said.
It is the usual cause of infectious mononucleosis, otherwise known as "mono"—a contagious disease common among teens and adults that is usually spread through saliva, so by kissing or sharing drinks and food.
After an individual is infected with EBV, the virus becomes inactive in their body, but may reactivate in some cases, with the potential for symptoms to resurface.
"It's a latent virus that resides inside of certain cells," Dr. Henry Balfour Jr., a professor in the Department of Laboratory Medicine and Pathology at the University of Minnesota Medical School, told Newsweek.
"So, when your immune system is challenged, let's say you get a flu shot or COVID, you're likely to see reactivation of EBV," he said.
Usual symptoms of EBV include fatigue, fever, inflamed throat, swollen lymph nodes in the neck, an enlarged spleen and swollen liver, as well as others.
The virus was previously classified as carcinogenic to humans, in the IARC's highest risk category (Group 1), in 1997.
To date, it has been directly linked to a few specific types of cancer, with studies estimating EBV-related cases accounted for between 239,700 to 357,900 new cases of certain cancers in 2020.
EBV has also been linked with rare diseases like multiple sclerosis (MS), a chronic and autoimmune neurological disorder, Lawrence Steinman, a professor of neurology and neurological sciences, and pediatrics at Stanford University, told Newsweek.
He also said that EBV, as a virus, may "trigger cancer itself," but that the antibodies one gets from EBV infection, may actually fight against certain cancers.
"In fact, strengthening the immune response to EBV is a way that the immune system fights the virus, and in doing so helps kill the cancer or attenuate its spread," he said. "The trade off comes with developing an autoimmune response to self proteins that may be contained in the cancer."
File photo: a computer illustration of the Epstein-Barr virus (EBV).
File photo: a computer illustration of the Epstein-Barr virus (EBV).
Dr_Microbe/Getty Images
What Did The Study Find?
The IARC study evaluated the cancer risk in two cohorts in Southern China of just under 74,000 adults. Over the course of around eight to 10 years, 964 cases of cancer were identified in the Zhongshan cohort and 1,026 in the Wuzhou cohort.
Researchers found that those who tested positive for EBV VCA-IgA antibodies were nearly five times as likely to develop cancer compared with individuals who tested negative.
There were also higher risks of developing certain cancers—for nasopharyngeal carcinoma, EBV VCA-IgA antibody positive individuals were found to be 26 times as likely to develop the disease.
Meanwhile, for lung cancer, they were 1.76 times as likely to develop the disease, for liver cancer, they were 1.70 times as likely to, and for lymphoma, they were 3.20 times as likely to.
Nasopharyngeal carcinoma, a type of cancer affecting the part of the throat that connects the back of the nose to the back of the mouth, had the highest risk among the cancer types investigated.
Authors of the study noted there was an increased cancer risk associated with higher levels of EBV VCA-IgA antibodies—an elevated risk that persisted even up to 10 years before diagnosis, which the IARC said suggested that EBV infection "may play a long-term role in cancer development."
Overall, the study estimated that 7.8 percent of the total cancer burden in Southern China could be attributed to EBV VCA-IgA antibody positivity in individuals.
Are Experts Concerned?
"I am not concerned about this finding," Luis Schang, a professor of chemical virology at Cornell University, told Newsweek, because it has been "long known" that EBV is associated with certain cancers.
"The major contribution of this study is linking the increase in cancer risk to likely reactivation," he said. Before this study, he said that it would be argued the risk of developing cancer was "independent" of virus reactivation.
Schang said that the study could also indicate that "antiviral, or vaccine, suppressive treatment could have a protective effect against the cancers produced by EBV."
Antiviral treatment can "inhibit" virus reactivation, Schang said, although it is still "extremely challenging" to treat, as the virus persists in human cells for a prolonged period.
He added that a vaccine that "could elicit strong immune responses" to curtail reactivation at early stages, potentially having an impact oncogenesis, the process where cells are transformed into cancer cells.
While the findings are notable, experts told Newsweek that more research still needs to be done on the issue.
"Most people, almost everybody who is infected with EBV, doesn't get cancer and doesn't get multiple sclerosis, so there's something else going on," Balfour Jr said.
He said that there is evidence of the effects of EBV, and its potential to cause long-term chronic diseases like cancer or autoimmune diseases, being "specific to geographical area and possibly the socioeconomic status of the people."
While it is not yet clear why this is the case, he said that "over and over again, socioeconomic status and race ethnicity are associated with the prevalence of EBV."
As a result, "I would be cautious in interpreting these findings to be of any concern to people in the U.S. - depending on your age and your socioeconomic status, about 90 percent of young adults and adults are positive for EBV and almost all of them are not going to get cancers or autoimmune diseases such as MS," Balfour said.