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and Ovarian Cancer
by Beth Crawford,
recent years, the medical community has learned about
both the genetic and nongenetic factors associated with
breast and ovarian cancers.
Although there is nothing people can do about their
genetic legacy, some nongenetic risk factors are in
areas that we can actually control.
new data from the past year suggests that these nongenetic
risk factors may differ in women who have a BRCA1
or BRCA2 mutation
than in women who do not have such a mutation. Because
these data are new, they are still considered preliminary.
However, it is important to keep your BRCA status in
mind when considering lifestyle changes to prevent breast
and ovarian cancer.
majority of breast and ovarian cancers are diagnosed
in women over the age of 50, making increased age one
of the primary risk factors for both of these types
of cancer. The exceptions to this are hereditary
breast and ovarian cancer, which are caused by alterations
in the BRCA1 and BRCA2 genes.
Breast cancer typically occurs in these women at a much
younger age, with an average age at diagnosis of about
average age at which ovarian cancer develops in women
who carry BRCA1 or BRCA2 mutations differs depending
on which gene their mutation is in. In BRCA1-related
cancers, the average age of onset is younger than in
the general population (54 years old compared to 62-63
years old in the general population). In BRCA2-related
cancers, the average age of onset is the same as in
the general population. This may suggest that women
with a BRCA1 mutation should consider risk-reduction
strategies for ovarian cancer at a younger age than
do women with a BRCA2 mutation.
recent years, scientists have discovered that long-term
exposure to estrogen
may increase a woman's chances of developing breast
and ovarian cancer. Estrogen levels are increased by
taking estrogen as a medication, but are also high in
ovulating women. Thus, anything that decreases the overall
time a woman ovulates, such as pregnancy, late onset
of menstruation, or early onset
of menopause, decreases her lifetime
exposure to estrogen and thus her risk for these types
of cancer. However, it is not clear that this same pattern
exists for women who have BRCA1 and BRCA2 mutations.
(For recent news about estrogen exposure affecting breast
cancer risk, see Related News below.)
Early-onset menstruation/late-onset menopause.
indicate that breast tissue is especially susceptible
to the effects of estrogen. Thus, the younger a woman
is when she begins menstruation, and the older she
is when menopause begins that is, the longer
her body is producing estrogen the greater
her risk of breast cancer. Scientists have found that
women who begin menstruating at 11 years of age or
younger are approximately 20 percent more likely to
develop breast cancer than women who did not have
their first period until age 14 or older. In contrast,
recent data suggest that the risk of breast cancer
in women who carry BRCA mutations is not influenced
by the age when menstruation begins.
younger a woman is when she begins menstruation,
and the older she is when menopause begins -
the greater her risk of breast cancer.
most women, pregnancy seems to provide some protection
against breast and ovarian cancer. In the case of
ovarian cancer, studies have shown that women who
have given birth are 30 to 60 percent less likely
to develop ovarian cancer than are women who have
never been pregnant. In fact, it appears that the
more times a woman has experienced childbirth, the
less likely she is to develop ovarian cancer. Research
also indicates that breast cancer risk is lower in
women who have had children, particularly if they
gave birth before the age of 30. Part of the reason
for this may be that pregnancy causes permanent changes
in a woman's breast tissue alterations that
appear to make it less likely that cancer will develop
there. Thus, having a baby at a young age provides
more protection. (For recent news about how child-bearing
history affects your breast cancer risk, see Related
who have given birth are 30 to 60 percent less
likely to develop ovarian cancer
It is unclear whether this same relationship between
pregnancy and breast cancer risk holds true in women
who have BRCA mutations. For the most part, recent
studies have found no relationship between age at
first pregnancy and breast cancer risk in these women.
There is also no consensus as to whether the number
of pregnancies changes the risk of breast cancer in
women who have BRCA mutations. Although one study
found that fewer pregnancies and later age at first
childbirth were actually protective against breast
cancer in mutation carriers, recent studies have not
confirmed this relationship.
breast cancer is among the more common types of cancer
in every major racial group, it occurs with varying
frequency among different populations. For example,
Caucasian women are slightly more likely to develop
breast cancer than are women of African descent, and
women of Asian and Hispanic descent have a lower risk
of breast cancer than those of African descent. Native
American women have one of the lowest rates of breast
cancer. Ovarian cancer is also more common among Caucasian
women, specifically those of North American and Northern
European descent. In the United States, Caucasian women
and women of Hawaiian descent are at the highest risk
for ovarian cancer, followed by women of African, Hispanic,
and Asian descent. Once again, the risk is lowest among
Native American women.
have found that women who have had breast biopsies
are at increased risk of developing breast cancer
even if those past biopsies did not reveal the presence
of cancer. Scientists do not believe, however, that
the biopsies themselves are responsible for the increased
breast cancer risk. Rather, they suspect that the women
having biopsies are already at increased risk
either because their breasts are lumpy and thus difficult
to examine, or because they are being followed for a
condition that increases their chances of developing
breast cancer (such as the precancerous condition atypical
hyperplasia or the nonmalignant
lumps called fibroadenomas).
Previous Breast Cancer or Precancerous Condition
who have already been diagnosed with breast cancer appear
to be at elevated risk for developing a subsequent primary
breast cancer (not a recurrence of the original cancer).
The risk for women with breast cancer is about 1 to
2 percent per year, or approximately 10 percent lifetime
risk of developing a second breast cancer. For women
with a BRCA mutations, the risk is about 5 percent per
year risk for a second breast cancer or a 40 to 60 percent
lifetime risk of a second primary breast cancer.
who were treated with chest radiation treatment as children
or young adults have a significantly increased risk
of breast cancer. One study showed that as many as 35
percent of women who had received radiation to treat
Hodgkin's disease prior to the age of 16 would develop
breast cancer by age 40. In addition, 85 to 100 percent
of the women in this group who did develop breast cancer
had tumors that were located within the area where radiation
was applied (or the margins of that area).
Hormone Replacement Therapy
who receive hormone replacement therapy
(HRT) to counter some of the effects of menopause may
be increasing their risk for breast cancer. It appears
that women who use therapies that include both estrogen
and progestin are at greater risk for breast cancer
than are women who use estrogen alone. According to
most studies, the risk of breast cancer increases by
approximately two percent per year of HRT use, so that
a woman who uses HRT for five years will have about
a ten percent increase in her risk of breast cancer
compared with if she had not used HRT. It is important
to note, however, that breast cancer risk with HRT applies
to current users and recent users, but a woman's breast
cancer risk returns to the general population risk level
within five years of stopping HRT.
also seems to increase breast cancer risk in women with
BRCA mutations who reach menopause before developing
breast cancer. (For
more information about how HRT affects breast cancer
risk, see Related News below.)
It is unclear whether HRT has an impact on a woman's
risk of developing ovarian cancer, however, most studies
suggest that there is not an association between HRT
and ovarian cancer. If you are considering taking HRT
in order to reduce your risk of ovarian cancer, it is
important to discuss the pros and cons of HRT with your
doctor. Include all personal risk factors in the decision,
including heart disease, breast and ovarian cancer,
Birth Control Pills
control pills substantially reduce the risk of developing
is very clear that oral contraceptives or birth control
pills substantially reduce the risk of developing ovarian
cancer. However, there is also evidence that they increase
the risk for breast cancer. Thus, any woman considering
the use of birth control pills must weigh the protection
they offer against ovarian cancer against the possibility
that they increase the risk for breast cancer. For women
with BRCA mutations who are at considerably increased
risk for both types of cancer this can be a very
women in the general population, oral contraceptives
(OCs) appear to cause a small increase in the risk of
breast cancer during the time the OCs are used and for
about ten years thereafter. However, because breast
cancer risk is low in very young women, the increase
in risk does not translate into a high risk of breast
cancer. For instance, only one additional case of breast
cancer would be expected among 20,000 women who used
OCs between ages 20 and 25.
a recent study has raised concern that in women with
inherited risk for breast cancer, oral contraceptives
may have a greater impact on the risk of developing
breast cancer. Although this study did not determine
whether the women had BRCA mutations, it showed that
in women who took OCs, the more family members she had
with breast cancer, the more her risk of breast cancer
increased. In women who had a sister or mother with
breast cancer, the risk of developing breast cancer
among OC users compared with non-users was 3.3 times
as great. The risk increased with increasing number
of family members, up to an 11-fold increase in risk
in women who had five or more family members with breast
cancer and used oral contraceptives, compared with those
who did not.
recent news about whether birth control pills increase
breast cancer risk, see Related News below.
studies have shown a 40 to 50 percent decrease in ovarian
cancer risk in women who take oral contraceptives
an effect that seems to increase with the amount of
time women use them. For example, studies have found
that the risk for ovarian cancer drops 10 to 12 percent
in women who have used oral contraceptives for a year
but that it drops by approximately 50 percent in those
who have taken birth control pills for five or more
years. In addition, it appears that the ovarian cancer
protection continues for at least 10 to 15 years after
a woman has stopped taking oral contraceptives.
findings of decreased risk for ovarian cancer apply
to women with BRCA1 and BRCA2 mutations as well: One
study found a 20 percent reduction in ovarian cancer
risk for BRCA1 and BRCA2 mutation carriers who had taken
oral contraceptives for as long as three years and a
60 percent reduction in risk for those who had taken
them for six years or longer. Because the risk of ovarian
cancer is high and this cancer is difficult to detect
with screening, OC's strong impact on ovarian cancer
risk in mutation carriers makes them an attractive offer
to consider. However, this must be weighed against the
recent data suggesting that they may substantially increase
the risk of breast cancer in mutation-carriers.
there is some evidence to suggest that ovarian stimulation
as infertility treatment increases the risk of ovarian
cancer, too few women have been studied for too short
a duration to establish a clear link. While early studies
suggested a large increase in risk, later studies have
not been able to confirm those findings.
scientists believe that breast feeding may reduce ovarian
cancer risk in premenopausal women, perhaps because
ovulation is suppressed during breast-feeding. They
also suspect that breast feeding may slightly decrease
a woman's risk of breast cancer, especially if breast
feeding is continued for 1.5 to 2 years. However, these
results are inconclusive, and other studies have found
lactation history to have no impact on breast cancer
there are many risk factors for both breast and ovarian
cancer that women can do nothing to change, there are
certain lifestyle-related risk factors that are within
their control, including:
a low fat diet
an active lifestyle
more news about how lifestyle factors can affect breast
and ovarian cancer risk, see Related News below.
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