By Dan Vergano, Medical Tribune News Service
A common virus may help trigger breast cancer, report French
researchers. There is no vaccine currently available for the
suspected pathogen, Epstein-Barr virus.
Over the past decade, scientists have discovered that some
viruses play a role in cancers. Epstein-Barr virus infects 9 out of
10 people worldwide, largely without any symptoms, but has been
associated with some throat tumors and more recently with Hodgkin's
disease, a cancer of the lymph nodes. Several studies have looked
for a viral cause of breast cancer, the most common type of tumor
afflicting women worldwide, according to the National Cancer
Institute in Bethesda, Md. Researchers failed to turn up any strong
associations between the virus and the cancer, however, until now.
Investigators led by Mathilde Bonnet of the Institut Gustav
Roussy in Paris examined tissue specimens from 100 consecutive
breast cancer cases. They report in the Wednesday edition of the
Journal of the National Cancer Institute that Epstein-Barr virus
appeared in 51 of the samples. For comparison, Bonnet's team found
the virus in only three of 30 samples of healthy tissue taken from
a random selection of the breast cancer patients.
``It seems likely at this time that Epstein-Barr virus is
frequently associated'' with breast cancer, wrote Dr. Ian Magruth
and Dr. Kishor Bhatia of the NCI, in an editorial accompanying the
study. Because the virus did not appear in all the tumors, they
suggest that more research is needed to determine what role the
virus may play in development of the disease. Breast cancer
requires numerous steps to arise, perhaps beginning with exposure
to environmental toxins in people with genetic susceptibilities,
the federal scientists noted. Infection with the virus may
aggravate pre-cancerous breast tissue, speculated Magruth and
Bhatia.
The French researchers found the virus more often in more severe
cases of breast cancer. Judging from this finding and the presence
of the virus inside cancerous lymph tissues in patients, they warn
that Epstein-Barr infection may make victims of breast cancer more
susceptible to metastasis, the spread of tumors throughout a cancer
patient's body.
This year, more than 176,000 women nationwide will be diagnosed
with breast cancer, according to the American Cancer Society in
Atlanta. Nearly 44,000 will die from the disease. Numerous risk
factors for breast cancer include increasing age, family history of
the disease, late menopause and early menarche.
Earlier studies to detect the virus in breast cancer patients
may have failed because researchers used only one type of DNA
analysis. The French researchers used several different methods,
detecting cases most effectively with polymerase chain reaction
(PCR) analysis, the type of DNA analysis relied on by crime
investigators. Earlier investigators had relied on a less
successful test that relied on detection of a protein used by
Epstein-Barr virus to survive. The authors speculated that the
virus' need the protein in tumors ``might not be universal.''
Magruth and Bhatia argued that if Epstein-Barr virus plays a
role in the development or metastasis of breast cancer, efforts to
develop a vaccine for the disease should be accelerated. The virus
belongs to the herpesvirus family of pathogens, nearly ubiquitous
throughout humanity in various forms, and has proven difficult to
eradicate using simple antibiotics.
