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Although scientists have been able to identify risk factors that increase a
woman's chance of developing breast cancer, the exact causes are not known.
Breast cancer is the most common type of cancer in American women. Over the past
50 years, the number of women diagnosed with the disease has increased each
year. Today, approximately one in every eight women will develop breast cancer
in her lifetime. Breast cancer is the second-leading cause of cancer death in
women -- second only to lung cancer -- and is the leading cause of cancer death
among women ages 35 to 54.
What are the risk factors for breast cancer?
Certain factors increase the risk of developing breast cancer. However,
having many risk factors does not mean a woman will develop breast cancer, and
having no risk factors does not mean she will not develop the disease.
Age is the single most important risk factor for breast cancer. The chances
of developing the disease increase with age. About 70 percent of women diagnosed
with breast cancer each year are over age 50, and almost half are age 65 and
older.
Personal risk is also greater if an immediate family member (mother, sister
or daughter) has had breast cancer, particularly if it was at an early age.
Also, women who have had a breast biopsy that shows certain types of benign
disease, such as atypical hyperplasia, are more likely to get breast cancer.
Other risk factors include:
- Having cancer in one breast (may develop in other)
- Late menopause (after age 50)
- Starting menstruation early in life (before age 12)
- Having a first child after age 30
- Never having children
How can I protect myself?
Detection of breast cancer in its early stages -- hopefully before it moves
outside the breast -- can significantly improve the chances that treatment will
be successful. The survival rate from breast cancer increases when the disease
is detected and treated early.
When a cancer is found in its earliest stages (within the breast), the 5-year
survival rate is 97 percent. This means that of 100 women diagnosed with breast
cancer at this stage, 97 will be alive after five years. More than half of all
breast cancers are diagnosed at this stage.
Once the cancer has spread outside the breast to nearby tissues (usually the
lymph nodes), the 5-year survival rate drops to 77 percent. When the cancer has
spread to more distant parts of the body, the 5-year survival rate is 21
percent.
Strategies for early detection
There are two methods of early detection that involve physical examination
of the breast: breast self-examination and clinical breast examination. The
American Cancer Society now recommends that women age 20 and older do a breast
self-exam each month, if women are comfortable doing their own exams. This
recommendation has changed recently because of
the awareness that self-exams may cause more anxiety and unnecessary testing.
But by doing the exam regularly, a woman becomes familiar with the normal feel
of her breasts and can more easily notice changes. Any change should be reported
promptly to a physician.
Women should have a clinical breast examination every year.
Mammography is an important method of early detection that uses low doses of
X-rays to take a picture of breast tissue. Screening is usually recommended at
the age of 40. The purpose of a mammogram is to find abnormalities that are too
small to be seen or felt. An ultrasound can distinguish between a cyst and a
solid lump. However, these tests will not detect all breast cancers, which is
why physical breast exams are very important.
To find out if you are at increased risk for breast cancer, consult your
physician. The National Cancer Institute has made available computer models for
predicting risk. Your doctor can tell you your estimated 5-year and lifetime
risks for breast cancer. If you are found to be at increased risk for breast
cancer, your screening may be performed at an earlier age or more frequently.
The genetics of breast cancer
Only 5 to 10 percent of breast cancer cases are thought to be hereditary.
The two most common genes associated with breast cancer -- BRCA1 and BRCA2 --
can be inherited from either parent. Therefore, the father's family history of
breast cancer is important as well.
At-risk families can take blood tests to screen for mutations in these genes.
However, genetic testing is done only when definitely indicated by a strong
family history. Other breast cancer syndromes may also be discovered with
genetic testing.
What are my options if I am at high risk for developing breast cancer?
There are an estimated 29 million women at increased risk for breast cancer.
Today, there are more options than ever before to help reduce this risk of this
cancer developing.
- Increased surveillance: High-risk candidates and carriers of the genes
associated with breast cancer can exercise several options, including beginning
screenings at an earlier age and conducting more frequent mammograms and
clinical exams.
- Bilateral prophylactic mastectomies: Some women choose preventive
mastectomy to decrease the chances of developing breast cancer, although this
doesn't offer complete protection.
- Tamoxifen chemoprevention: Another approach includes chemoprevention
strategies, such as using the anti-estrogen drug tamoxifen (Nolvadex).
In September of 1998, the NCI and the National Surgical Adjuvant Breast and
Bowel Project (NSABP) published the report of their breast cancer prevention
trial. The trial was designed to determine whether tamoxifen would reduce the
incidence of breast cancer in healthy women known to be at high risk. The
results of the trial showed a 50 percent reduction in both invasive and
non-invasive breast cancer in the treated women.
- STAR (Study of Tamoxifen and Raloxifene) trial: Sponsored by NSABP,
this 5-year clinical trial began in May 1999 and enrolled approximately 19,000
postmenopausal women at high risk of breast cancer. It is a breast cancer prevention trial that is comparing tamoxifen and raloxifene for reducing breast cancer risk.
Researchers are expected to report study results sometime in 2006.
- Ductal lavage: This minimally invasive procedure looks at cells that
line the milk ducts to determine whether they are abnormal. It is an option for
women who are at an increased risk for breast cancer and have normal mammograms
and breast exams. This procedure doesn't reduce the risk of breast cancer, but
tries to determine a woman's actual risk for developing breast cancer over time.
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