Herpes simplex
virus 2, the virus that causes genital herpes, also helps the human papilloma
virus in triggering cervical cancer, a new study suggests.
"HSV-2 may increase
the likelihood that an HPV infection may infect the cervix by having access
to the basal cell layer," which is underneath the surface layer, lead researcher
Jennifer Smith, of the International Agency for Research on Cancer, told
United Press International. "HSV-2 infections are also characterized by
inflammation that may cause DNA damage that may increase cancer risk,"
she said, adding HSV-2 also seems to bring out the worst in HPV by causing
it to replicate and destroy healthy cells.
It has long
been known that HPV -- a sexually transmitted virus -- is the main cause
of cervical cancer, a disease that is highly curable if caught early. What
is less known is whether HSV-2 -- which can remain dormant for years --
also exacerbates cervical cancer.
Smith and colleagues,
of the IARC's Multicentric Cervical Cancer Study Group in Lyon, France,
examined blood and cervical samples from 1,263 cervical cancer patients
and another 1,117 women without the disease. They tested for traces of
DNA, or genetic material, from HPV and looked for antibodies to the herpes
virus -- immune system cells that fight the virus specifically.
As reported
in the Nov. 6 issue of the Journal of the National Cancer Institute, they
found herpes antibodies in the blood of 44.4 percent of the women with
cervical cancer and in 43.8 percent of the women with a type of invasive
cervical cancer. In contrast, they detected herpes virus antibodies in
only 25.6 percent of the women who did not have cancer.
HPV was found
in 94.8 percent of the cervical cancer patients and among 90.5 percent
of women with invasive cervical cancer.
Women who tested
positive for HPV and prior herpes infections were associated with more
than a two-fold increase in cervical cancer risk and more than a three-fold
increase in risk for invasive cervical cancer, a particularly aggressive
form of the disease.
"Given that
women who have HSV-2 infection for a longer amount of time are likely to
have a greater number of recurrent herpes infections, ... one would expect
that women who acquired HSV-2 infections for a longer amount of time would
be at a greater risk of cervical cancer," Smith explained.
"I thought it
was an impressive study," said Dr. Hildemund Ertl, an immunologist and
medical research scientist at the University of Pennsylvania in Philadelphia
who is studying ways to develop HPV
vaccines.
Ertl said women
are vulnerable because the herpes virus is difficult to treat. The herpes
virus might interfere with the natural regulations used to prevent cells
from growing out of control, which leads to cancer.
"So that's one
possibility," Ertl told UPI. Genetic fragments from the herpes virus also
might cause changes in damaged cells, Ertl said, though she added, "I'm
not sure if that's really been proven, though".
Another sneaky
aspect of the herpes virus -- which might explained how it works in conjunction
with HPV -- is "it tricks the immune system," Ertl said, so the immune
system might not even be able to recognize it. "Once you have the virus,
there really isn't much you can do right now."
Women are advised
to get regular Pap smears, which involves doctors taking a swab from the
cervix to test for any abnormal cell activity. Ertl said there is ongoing
research to discover the first effective and safe HPV vaccine. There also
is research into herpes vaccines, but "none of them actually look all that
promising," she said.
The Journal
of the National Cancer Institute is a publication put out by Oxford University
Press and is not affiliated with the National Cancer Institute in Bethesda,
Md.
--
Copyright 2002 by United
Press International.
All rights reserved.
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