Using a comprehensive nationwide medical database, investigators in Denmark compared 17,000 people with mononucleosis caused by Epstein-Barr virus to more than 24,000 people who were suspected of having mono, but did not have evidence of EBV.
The risk of Hodgkin's disease was higher in people with a positive antibody blood test that confirmed mononucleosis caused by EBV. No increased risk in Hodgkin's disease was found in those people suspected of having mono but testing negative for EBV.
An association between EBV and Hodgkin's disease has long been suspected. Studies have shown that there is a higher rate of the cancer in people with a history of mononucleosis. Studies also show that the virus is present in about 50% of these tumors.
In the current study, researchers found that mono caused by EBV quadrupled the risk of Hodgkin's disease. Mono-like illnesses caused by other viruses, such as cytomegalovirus, were not associated with Hodgkin's.
In addition, mono was directly linked to lymphomas that contained EBV and not to lymphomas with no evidence of the virus.
The findings are reported in the Oct. 2 issue of The New England Journal of Medicine.
From Mono to Lymphoma
The researchers estimated the average time between mononucleosis developing into Hodgkin's disease to be four years, with risks peaking two years after infection.
"But it is important to stress that while mononucleosis does increase the risk of getting Hodgkin's lymphoma, the risk is still very small -- on the order of one case of the cancer per 1,000 patients," study co-author Mads Melbye, MD, tells WebMD. "And it appears from this research that not all cases of Hodgkin's disease are related to this virus, as some people have suggested."
The Kissing Disease
Infectious mononucleosis, colloquially known as the "kissing disease," is caused by Epstein-Barr virus infection. Almost everyone becomes infected with the virus at some point in his or her lives, and those infected during childhood rarely become ill. But between one-third and half of people infected during adolescence and young adulthood develop the illness, mononucleosis.
Hodgkin's disease is a cancer of the lymph nodes, which are part of the immune system and help fight infection and cancer. Hodgkin's disease is one of the most common malignancies among teens and young adults.
Researchers have suspected that infection with Epstein-Barr virus sets the stage for Hodgkin's disease by weakening the immune cells that help fight off cancer.
A Direct Link?
We have shown a direct link between infection with EBV and tumors that contain EBV, Melbye says.
But in an editorial accompanying the Danish study, Johns Hopkins oncologist Richard F. Ambinder, MD, PhD, questions whether EBV infection still may play a role in lymphomas not found to contain the virus.
As evidence of this, he makes note of Hodgkin's disease that runs in families. He says that both lymphomas with and without EBV have been found to run in families. "Hence, it is not appropriate to presume that EBV-positive and EBV-negative lymphomas are distinct entities."