In a study published in a recent issue of the Journal of the National Cancer Institute, researchers analyzed 100 biopsies from patients with early stage breast cancer along with 30 samples of healthy tissue taken from the area of the breast adjacent to the tumor. EBV was found in 51 of the 100 biopsies while only three of the 30 healthy samples contained the virus.  "There was a statistically significant difference in the detection of EBV DNA between the malignant and healthy tissue, strongly suggesting that EBV is largely restricted to the tumor," said study co-author Irene Joab, PhD, of The French Institute of Health and Medical Research (INSERM) in Paris.

Because the virus was more frequently associated with the most aggressive tumors, it may play some part in their development, according to the researchers. They observed that the EBV infection was associated with lymph node invasion, which suggests the infection may be related to the high potential of the tumor to spread.
 
In recent years, studies have suggested the virus plays a role in the development of cancers including Hodgkin’s disease, B-cell lymphoma, and cancers of the nose and throat. EBV is a very common virus that infects nine out of 10 people worldwide. Most people infected with the virus have no symptoms.

In an accompanying editorial, authors Ian Magrath, MD, and Kishor Bhatia, PhD, of the National Cancer Institute (NCI) wrote, "If EBV does prove to play a role in the development of breast cancer, there would be strong grounds for speeding up the development of an EBV vaccine."

Debbie Saslow, PhD, director of breast and cervical cancer for the American Cancer Society (ACS), said the French study points to a need for more research into the nature of the link between breast cancer and EBV. "At this point, the study does not suggest any causal relationship between the virus and cancer," she said.

Dr. Joab said research is already under way to find out if the virus is causing tumor growth. Research into EBV also could help with choosing treatment and predicting cancer outcomes, she said.

The ACS estimates 175,000 women will be diagnosed with breast cancer this year in the US, and about 43,700 women will die of the disease.