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In 1940, the lifetime risk of a woman developing breast cancer
was 5%, or one in 20. In 1997, that risk was estimated at 12%, or one in eight.
In many cases, it's not known why a woman gets breast cancer. In fact, 60% of
all women with breast cancer have no known risk factors.
What are the risk factors of breast cancer?
A risk factor is anything that increases a person's chance of
getting a disease. Different cancers have different risk factors.
But having a cancer risk factor, or even several of them, does
not necessarily mean that a person will get cancer. Some women with one or more
breast cancer risk factors never develop it, while most women with breast cancer
have no apparent risk factors.
Significantly higher risk
History of previous cancer in one breast, especially if it
occurred before menopause (menopause increases breast cancer risk 3- to 4-fold)
increases a woman's risk of developing a new breast cancer unrelated to the
first one. This is different than a recurrence of the previous breast cancer.
Moderately higher risk
- Getting older. Your risk for breast cancer
increases as you age. About 77% of women diagnosed with breast cancer each
year are over age 50, and almost half are age 65 and older. Consider this:
In women 40 to 49 years of age, there is a one in 66 risk of developing
breast cancer. In the 50 to 59 age group, that risk increases to one in 40.
- Direct family history. Having a mother, sister
or daughter ("first degree" relative) who has breast cancer puts
you at higher risk for the disease. The risk is even greater if your
relative developed breast cancer before menopause and had cancer in both
breasts. Having one first-degree relative with breast cancer approximately
doubles a woman's risk, and having two first-degree relatives increases her
risk 5-fold. Having a male blood relative with breast cancer may also
increase a woman's risk of the disease.
- Genetics. Carriers of either of two familial
breast cancer genes called BRCA1 or BRCA2 are at higher risk. Ten percent of
women are carriers of this gene.
- Breast lesions. These include multiple
papillomatosis, atypical ductal hyperplasia, and lobular carcinoma in situ.
Slightly higher risk
- Distant family history. This refers to breast cancer in
more distant relatives such as aunts, grandmothers and cousins.
- Large cysts in the breast. Large cysts increase your risk
especially if accompanied by early atypical hyperplasia (abnormal cell changes
in the breast). A previous breast biopsy result of atypical hyperplasia
increases a woman's breast cancer risk by 4 to 5 times.
- Age at childbirth. Having your first child after age 30
or never having children puts you at higher risk.
- Early menstruation. Your risk increases if you got your
period before age 12.
- Late menopause. If you begin menopause after age 55, your
risk increases.
- Weight. Being overweight (especially in the upper body),
with excess caloric and fat intake, increases your risk, especially after
menopause.
- Excessive radiation. This is especially true for women
who were given radiation for postpartum mastitis, received prolonged
fluoroscopic X-rays for tuberculosis or who were exposed to a large amount of
radiation before age 30 -- usually as treatment for cancers such as lymphoma.
- Other cancer in the family. A family history of cancer of
the ovaries, cervix, uterus or colon increases your risk.
- Heritage. Female descendents of Eastern and Central
European Jews (Ashkenazi) are at increased risk.
- Alcohol. Use of alcohol is linked to increased risk of
developing breast cancer. Compared with nondrinkers, women who consume one
alcoholic drink a day have a very small increase in risk, and those who have 2
to 5 drinks daily, have about 1.5 times the risk of women who drink no
alcohol. Alcohol is also known to increase the risk of developing cancers of
the mouth, throat, and esophagus.
- Hormone replacement therapy. Combination estrogen-progestin
hormones taken during menopause increase a woman’s risk of developing breast
cancer by 26%. This risk increases with longer use of hormones.
Low risk
- Pregnancy before age 18
- Early onset of menopause
- Surgical removal of the ovaries before age 40
Factors not related to breast cancer
- Fibrocystic breast changes
- Multiple pregnancies
- Coffee or caffeine intake
- Antiperspirants
- Underwire bras
- Abortion
- Breast implants
There are other factors that may affect your risk for breast
cancer, but medical research has not yet determined the exact role they play.
They include taking birth control pills for many years. Also, scientists are
still investigating whether smoking, high-fat diets, lack of exercise and
environmental pollution increase breast cancer risk.
Do most women with breast cancer have a family history of the
disease?
No. Women with a family history of breast cancer account for
only 25-30% of all women with the disease. If you have a relative who has breast
cancer, you have an increased risk. Still, three-fourths of women with a family
history of breast cancer will not develop the disease. Even if you don't have a
family history of breast cancer, you're still at risk for developing the
disease, especially after age 50.
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