Fetal Cells Protect Against Breast Cancer
< Oct.
03, 2007 > -- October is Breast
Cancer Awareness Month and a well-known
risk factor for breast cancer has just received
validation.
Not having children is often cited
as a risk factor in the development of cancer. According
to the American Cancer Society
(ACS), women who have had no children or who
had their first child after age 30, have a slightly
higher breast cancer risk. Having multiple pregnancies
and becoming pregnant at an early age also seems
to reduce breast cancer risk.
Some benefits of motherhood are
intangible, but one has been validated through biostatistical
research. Women who bear children have a reduced
risk of developing breast cancer. Researchers at
the University of Washington and Fred Hutchinson
Cancer Research Center believe they have identified
a source of this protective effect - fetal cells
taking up residence in the mother before birth.
Their findings are presented in Cancer
Research, a journal of the American
Association for Cancer Research (AACR).
To test the idea, the researchers
recruited 82 women, 35 of whom had been diagnosed
with breast cancer. Approximately two-thirds of the
women studied had given birth and more than half
of the participants had given birth to at least one
son.
The researchers
took blood samples from each participant and searched
them for male
DNA. The rationale for this is that it is a relatively
definitive matter to detect the male Y chromosome
amid the mother’s native - and obviously female
- cells within a blood sample.
Among the women with breast cancer,
only five had male DNA in their bloodstream. Three
of the five previously gave birth to sons, one had
had an abortion and the other had never been knowingly
pregnant.
In total, about 14 percent of
all women in the breast cancer group had male DNA
in their bloodstream compared to 43 percent of women
in the non-breast cancer group.
"Our research found that these
persisting fetal cells may be giving a woman an edge
against breast cancer," says Dr. Vijayakrishna K.
Gadi, assistant professor at the University of Washington
and research associate at the Fred Hutchinson Cancer
Research Center. "This experiment of nature is all
the more fascinating because for years doctors treated
a number of different cancers by transplanting cells
from one person to another."
The ability of cells from a growing
fetus to take up long-term residence within its mother
is a phenomenon called fetal microchimerism.
According to the researchers,
while fetal microchimerism has been implicated as
a mechanism of autoimmune disease, it may also benefit
mothers by putting the immune system on alert for
malignant cells to destroy.
According to Dr. Gadi, these findings
could provide a starting point for future research
on the role of fetal microchimerism in the prevention
of cancer.
In addition, there
are other reasons for male DNA to be in a woman’s peripheral
blood, reasons such as miscarriage and abortion – or
possibly even blood transfusion or a male twin that
was reabsorbed into the womb at an early stage of
the pregnancy. Hopefully researchers will be able
to find a way to use this information to prevent
breast cancer in women who do not have children.
If you have concerns about your
breast cancer risk, consult your physician for more
information.
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