Epstein – Barr virus found to be most common cause of breast cancer

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Findings from a cross continent study published in the Journal EBioMedicine revealed that Epstein-Barr virus is a leading cause of breast cancer. The studies conducted in India, North Africa, China, and southern Europe all noted a relationship.

Epstein-Barr virus (EBV), a member of the herpes virus family, is easily transmitted through oral transfer of saliva and by genital secretions. An incredible 90 percent of all humans on earth are thought to be infected by EBV.
Most sexually active adults will pick up the virus at some point in their lives, and about half of all 5-year-olds have evidence of previous infection. Although the majority of carriers do not display any symptoms of infection, it can lead to complications in some individuals, most commonly, infectious mononucleosis, also known as glandular fever. EBV infects two major cell types, firstly, components of the immune system, known as B cells; secondly, epithelial cells, which line cavities of the body, blood vessels, and organs.

Over the years, EBV has also been associated with a number of specific cancer types such as African Burkitt lymphoma (a cancer of the lymphatics), Hodgkin’s disease (a blood cancer), nasopharyngeal carcinoma (a rare head and neck cancer), gastric adenocarcinoma (a type of stomach cancer), and leiomyosarcoma (a smooth muscletumor). An estimated 200,000 malignancies are caused by EBV annually.
Although EBV’s relationship with cancer generation has been demonstrated, it has proven tough to pin down the processes behind it. Often, the breast cancer will not appear for many years after the initial viral infection, making a causal role difficult to establish.

According to Dr Gerburg Wulf, the researchers cultured breast cells in the presence of EBV; specifically, they used cells known as primary mammary epithelial cells (MECs). The team found that EBV binds to a specific receptor on normal breast cells called CD21, which leads to infection. The viral infection caused the breast cells to behave like stem cells – they were able to keep on dividing. Dr. Wulf and his team implanted MECs into mice; they noted that the EBV infection assisted some cancer types, enabling certain proteins to speed up the formation of breast cancer. When the genes of the MECs infected by EBV were examined, they saw genetic characteristics normally associated with a particularly aggressive breast cancer – highgrade, estrogen-receptor-negative breast cancer. Although the results will need to be replicated and other aspects of the pathway examined, the findings add to our understanding of the causes and influences of breast cancer.
Furthermore, the researchers were of the opinion that if a young woman develops EBV during her teenage years or later, her breast epithelial cells will be exposed to the virus and can be infected.

While for most individuals, there will be no long-term consequences, in some, the infection may leave genetic scars and change the metabolism of these cells. While these are subtle changes, they may, decades later, facilitate breast cancer formation.