MONDAY, Oct. 31 (HealthDay News) -- Women who have a relative
with breast cancer linked to the high-risk BRCA genetic mutation
understandably worry about their own risk.
Now, a new study suggests that women who don't test positive for
the mutations are not at an extremely high risk of getting breast
cancer, even if they have a relative with BRCA-related breast
Their risk is similar to that of women with relatives with
non-BRCA-related cancers, the new research indicates.
This refutes a finding from a 2007 study, which found a two- to
five-times higher risk for these women, even if they tested
negative for the mutations, said senior study author Dr. Alice S.
Whittemore, a professor of health research and policy at Stanford
University School of Medicine.
Based on the new research, she said, the bottom line is this:
"If you are in a family where there is a BRCA mutation and you do
not have that mutation, your risk of breast cancer is no greater
than anyone with a family history of [other types of] breast
According to the American Cancer Society, having one
first-degree relative, such as a mother, sister or daughter, with
breast cancer doubles a woman's risk of getting it. Having two
close relatives increases the risk about threefold.
Whittemore calls the new finding "very, very reassuring" because
it suggests that having a family history of the BRCA mutation, by
itself, is not a risk factor, she said.
The study is published online Oct. 31 in the
Journal of Clinical Oncology.
Women with a BRCA1 or BRCA 2 gene mutation have a 5- to 20-fold
higher risk of getting breast or ovarian cancer, the Stanford
researchers wrote. That means a lifetime probability of up to 65
percent for breast cancer, and up to 40 percent for ovarian
Women who have the BRCA1 and BRCA2 mutations and are cancer-free
are urged to step up their screening and to begin it early, by age
25, among other measures. They may also consider a preventive
mastectomy or ovary removal after childbearing is done.
However, the 2007 study, Whittemore said, "sent an alarm signal
to the medical community" as it suggested a high risk even in
After the study was published, she and her colleagues took a
closer look. "What we thought to be the flaw was that they were
comparing these relatives of women with breast cancer to the
general population. A better comparison group would have been women
who have relatives with breast cancer but no mutation," Whittemore
said. "That's what we did."
The new study looked at 3,047 families from the United States,
Australia and Canada. It included 160 families with BRCA1 and 132
with BRCA 2. The researchers compared cancer risk in women who
tested negative but had relatives with BRCA-related breast cancer
with a group of cancer-free women who had relatives with cancer
that wasn't BRCA-related.
They found no increased risk for the women who were
BRCA-negative and had close relatives with BRCA-related cancer.
In other words, Whittemore said, their risk is "no greater than
anybody with a family history."
Besides BRCA1 and BRCA2 mutations, other risk factors, not
totally understood, that can run in families also drive breast
cancer risk, experts say. One example is drinking habits.
The findings suggest that BRCA-negative women can follow the
same breast cancer screening routine as the general population, if
they have no other strong risk factors, Whittemore said.
The findings should be reassuring to women without the mutation,
agreed Dr. Patricia Ganz, director of cancer prevention and control
research at the University of California's Jonsson Comprehensive
The results do suggest that women in a family where BRCA-related
breast cancer had occurred who themselves are negative for BRCA
mutation may have a slightly increased risk "because there are
other things that influence getting breast cancer besides having
the gene mutation," she said.
"The main message," she said, "is that these women [without the mutation] don't need all that extra surveillance."
Testing for BRCA mutations requires a sample of blood or cells
be taken from the mouth, said Rebecca Chambers, a spokeswoman for
Myriad Genetics, which provides the test.
The samples can be collected at any lab and mailed in for
analysis. The test costs $3,340, she said, but the average out-of
-pocket cost is $100 after insurance coverage.
For more on BRCA mutations, go to
U.S. National Cancer Institute.