Glandular fever
virus linked to breast cancer
Reported May 19, 2010
A common childhood virus may significantly boost the risk
of breast cancer, according to researchers who think infection with it late
in life may be a trigger for some of the cancers.
Dr Ann Richardson, an epidemiologist at Otago University's Christchurch
School of Medicine and Health Sciences, uncovered the intriguing new links
between cytomegalovirus (CMV) and breast cancer.
CMV is a common virus that infects most people at some time during their
lives but rarely causes obvious illness. It is a member of the herpes virus
family.
Richardson published a study in the British Journal of Cancer, showing women
who developed breast cancer when aged under 40 years were more likely to
have recently been exposed to CMV, than were women without breast cancer.
If late infection with CMV is proven to increase the risk of breast cancer,
some countries may consider immunising children against it, Dr Richardson
said.
The research appeared six years, to the day, after she and Otago colleague
Associate Professor Brian Cox first published research in the journal
investigating CMV and another common virus, Epstein-Barr virus (EBV).
EBV is a common human virus, both it and CMV can cause glandular fever.
The team made its latest breakthrough by comparing stored blood samples in
Norway with a cancer register and showed that elevated antibody levels in
the blood for CMV preceded the development of breast cancer in some women.
They did not find a similar link between EBV and breast
cancer.
Richardson said the pattern of infection with CMV differed between
countries, and in countries with the lowest incidence of breast cancer,
nearly everyone was exposed to CMV in early childhood.
But in countries such as New Zealand, where the incidence of breast cancer
is high, many women are not exposed to CMV until adulthood.
CMV is spread in breast milk as well as saliva, urine, cervical secretions
and semen.
Initial work with Cox and Professor Margaret McCredie at the Dunedin School
of Medicine, and researchers at the University of Melbourne, found the risk
of breast cancer in 377 Australian women aged under 40 rose with the level
of CMV antibodies in their blood.
The team concluded higher CMV antibodies measured in young women with breast
cancer could be the result of more recent viral infection.
Cox said the latest study, of blood samples taken up to 17 years before
Norwegian women were diagnosed with breast cancer, found women infected with
CMV as adults had four times the breast cancer risk in women not infected as
adults.
And this increased risk was nine-fold in women who had had children.
The increased risk was seen in only a small number of the breast cancer
patients - other factors likely contributed to cancer in most women.
The link between adult CMV infection and breast cancer fitted neatly with a
lower risk of cancer seen in women who started giving birth while relatively
young and went on to have a number of children.
New young mothers not previously infected with CMV might pick up the virus
when their children caught it from playmates, and would be able to develop
immunity while young.
And the more children in the family, the more likely it was that a mother
would be exposed to CMV while young.
Several other cancers such as cervical cancer, liver cancer and a type of
leukaemia are known to be caused by viruses, and a vaccine has been produced
to protect women against the virus involved in cervical cancer.
About 2,000 women develop breast cancer in New Zealand every year, making it
the most common cancer in women, but most are over the age of 40.
Source : TVNZ Daily & Breaking News
