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No one understands exactly why breast cancer seems to run in some families and
not others, but physicians are getting better at predicting which of us is more
likely to be stricken. Whatever the underlying reason may be, family history
definitely does play a significant role. If your mother, sister, or daughter (known
as first-degree relatives) have had breast cancer, your estimated risk is 1.5 to 3
times higher than that of a woman whose close female relatives are breast
cancer-free. If two first-degree relatives have had breast cancer, your risk
increases five-fold.
The older you are, the greater your chance of developing this frightening disease.
Breast cancer rarely occurs before the age of 20. The odds of developing it
increase sharply with age until menopause. After that, the chances of developing
breast cancer continue to rise with age, but not as rapidly.
The longer a woman remains fertile, the greater her chances of developing breast
cancer. If you started having periods early (before the age of 12) or stop having
them late (after the age of 55) youre in the high-risk group.
Pregnancy seems to short-circuit the process under certain circumstances. The
earlier a woman completes her first full-term pregnancy, the less likelihood she
has of contracting the disease. For example, a womans lifetime risk of developing
breast cancer drops by as much as 70 percent when she has a baby before her
eighteenth birthday. This beneficial effect steadily tapers off during her 20s and
seems to vanish entirely by the time she reaches the age of 30. Women who have
their first baby after the age of 35 are twice as likely to develop breast cancer as
those who give birth while still in their teens. Abortion does not appear to
increase your risk of breast cancer, though this issue is not definitively settled.
And what of the widespread belief that breastfeeding naturally protects a nursing
mother from breast cancer? At present, its still under scientific debate.
Like early motherhood, the removal of the ovaries seems to offer some
protection against breast cancer. If a womans ovaries are surgically removed, her
chances of getting breast cancer can fall by as much as 75 percent. How much
this procedure cuts your risk depends upon your weight, your age at the time of
surgery, and whether you have had children. The greatest benefit accrues to
young, thin women who have never had children. Removing only one ovary also
reduces the risk of breast cancer, but to a lesser degree than removing both.
Other probable risk factors are harder to pinpoint. For example, breast cancer is
most common among Caucasians and occurs much less often among Asians. But
despite a very low rate of breast cancer among Japanese women who stay at
home, the risk rises sharply among those who have moved to the United States --
a phenomenon that has convinced some scientists of a link between environment
and development of the disease.
Although black women are less likely to develop breast cancer than white
women, black women are more likely to die of the disease.
For some reason, breast cancer seems to occur more often among the wealthier
and better educated. Some data suggest that alcohol use or a high-fat diet
increases risk of breast cancer, but this has not been confirmed. Smoking does
increase the risk of breast cancer for some postmenopausal white women. Other
studies suggest that vigorous exercise at certain ages may reduce the risk.
Women who have previously had cancer of one breast are at higher risk of
developing it in the other. Women with a certain type of noncancerous lesion in
the breast, called a radial scar, are more likely to develop cancer where the scars
are found.
Because the breast is extremely vulnerable to the effects of radiation, previous
exposure to radiation increases the odds of breast cancer, especially for women
exposed before the age of 30. Exposure as a young girl is a particular cause for
worry.
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