Experts
Look Closely at Gauging Breast Cancer Risk
Current methods of gauging a woman's breast cancer
risk that rely on her family history may underestimate the danger,
says a study in the Journal of the American
Medical Association.
Using risk assessment models helps physicians determine
whether or not a woman carries the BRCA1 or BRCA2 gene mutations that
would predispose her to breast cancer.
If
a woman’s family history
suggests she might carry such a gene, physicians can offer screening
for the mutations.
The new study found that there may be a better way
to refine the risk model so those predictions are more accurate.
"In some circumstances, we have to qualify what
family history can tell us," says lead researcher Dr. Jeffrey Weitzel
of City of Hope Comprehensive Cancer Center.
He
points out that family history data is not always available to women,
and "if there's no family,
then you can't have a family history, if you don't have older women
in either lineage."
Dr.
Jay Brooks of Ochsner Health System, says, "We're
trying to predict which women should get tested [for a genetic predisposition].
“The test is expensive, and not every woman
can get it," adds Dr. Brooks. However, "with smaller families today,
many times you don't have that extensive family tree that you can reconstruct.”
The implications could be lifesaving for many women.
Mutations in BRCA 1 and BRCA 2, especially, can greatly increase a
woman's risk of developing both breast and ovarian cancer.
"It's now medically necessary that access to care
should be broader, and more people should be able to take advantage
of [gene screening], because it may make a big difference in outcome," notes
Dr. Weitzel.
"Failure to recognize that a woman happens to be
a BRCA carrier and do appropriate prevention procedures could cost
a woman her life," he says.
Although BRCA mutations are relatively rare (affecting
only about 5 percent of the population), those with the misfortune
to carry them have a 50 percent to 85 percent greater chance of developing
breast cancer and a 16 percent to 50 percent higher risk of developing
ovarian cancer.
Women with breast cancer who have a BRCA mutation
also have a higher risk of developing another breast cancer or ovarian
cancer. A mastectomy or oophorectomy (removal of the ovaries) can significantly
reduce that risk.
Most of the methods available to estimate how likely
a person is to carry the BRCA 1 or BRCA 2 defects were developed using
data from large families. They incorporate information on family history,
age at diagnosis, and ethnic ancestry.
It is these models that are most often used by insurance
companies when deciding whether or not to pay for the gene test.
But the fact that a woman's father might have passed
on the mutation is often not taken into account, explains Dr. Weitzel.
"Half of all heredity for breast cancer comes from
dad," he says. "Most clinicians don't realize that BRCA can be inherited
through dad."
Then there are women with early-onset breast cancer
but no history of breast or ovarian cancer, or patients with less than
two female relatives surviving beyond age 45 on each side of their
family. The model does little to help them, experts say.
For the study, Dr. Weitzel's team combed through
information on more than 1,500 women cared for at high-risk breast
cancer clinics in the US.
The conclusion was that women under 50 with breast
cancer and a limited family structure - less than two females age 45
or older on either side of the family - were almost three times more
likely to be BRCA carriers than women with adequate family structure.
BRCA gene mutations were found in 13.7 percent of
women with limited family structure compared with 5.2 percent of those
with adequate family structure.
Dr.
Weitzel now believes that "family
history is not a good tool. We shouldn't discriminate against women
[who have
limited family structure]. What if she's adopted? We lost whole generations
to the Holocaust. Why should we deny them access to testing?"
In women with little family history to rely on,
age may end up being a deciding factor in assessing BRCA-linked breast
cancer risk.
Women under 40 who have breast cancer are usually
tested for the BRCA mutations, but women in the next decade of life
probably should be as well, the researchers say.
"Most crucial is the 40-to-50 age range," says
Dr. Weitzel.
"Younger women who have breast cancer, especially
those below 50, really should raise a red flag about genetic testing," adds
Dr. Brooks.
"Age is a very, very powerful thing. The average
age for developing [breast cancer] is 60. If you're developing disease
10 years before you're expecting to, that should raise a red flag," says
Dr. Brooks.
"You're trying to predict who deserves the test," he
continues. "With small family numbers, we may be underestimating who
needs to be tested."
Always consult your physician for more information.
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