While there's no known exact cause of breast cancer, it’s known that the disease
occurs when some breast cells begin growing abnormally.
These cells divide more rapidly than healthy cells and then start to
accumulate, forming a lump or mass.
These cancer cells can spread (metastasize) throughout the breast and into
lymph nodes or to other parts of your body.
Most of the time, breast cancer begins with cells in the milk-producing
ducts. But it can also begin in the glandular tissue called lobules, or in
other cells within the breast.
Risk Factors for Breast Cancer
While some people who get breast cancer don't have any of the following
risk factors, these traits increase your risk of developing breast cancer:
- Being a
woman
- Obesity
- Older
age
- Personal
history of breast cancer in one breast (increases your risk of getting it
in the other breast)
- Family
history of breast cancer in close relatives such as your mother, sister,
or daughter - especially if they developed the disease at a young age
- Inherited
genetic mutations, such as BRCA1 and BRCA2
- Radiation
exposure to your chest as a child or young adult
- Starting
your menstrual cycle before the age of 12
- Beginning
menopause at an older age
- Giving
birth for the first time after the age of 35
- Never
being pregnant
- Taking
hormone therapy that combines estrogen and progesterone
- Drinking
alcohol
Inherited Breast Cancer
The majority of breast cancers are not inherited. In fact, only 5 to 10
percent of breast cancers are linked to genetic mutations passed down through
generations.
The most common gene mutations linked to breast cancer are BRCA1 and BRCA2.
Both of these mutations also increase the risk of other cancers throughout a
woman's lifetime, particularly ovarian cancer.
In normal cells, the BRCA1 and BRCA2 genes help prevent cancer by making
proteins that keep the cells from growing abnormally. If these genes are
mutated, the cancer-prevention response will not work properly.
For some women with the BRCA1 mutation, the lifetime risk of breast cancer
is as high as 80 percent. On average, however, this risk is more like 55 to 65
percent.
For women with the BRCA2 mutation, the lifetime risk of breast cancer is
around 45 percent.
Breast cancers linked to these mutations occur more often in younger women.
Cancer affecting both breasts is also more common than in cases not linked to
these mutations.
While the BRCA1 and BRCA2 mutations may affect anyone, they are more common
in Jewish people of Eastern European origin than in other racial and ethnic
groups in the United States.
Men can also carry these mutations, and if they do they are at increased
risk for breast and other cancers, such as prostate cancer.
Genetic Testing
Genetic testing may be an option if you have a family history of breast
cancer or other cancers.
Through a blood or saliva test, scientists can identify specific inherited
mutations in BRCA or other genes.
Talk with your doctor about whether genetic testing is a good option for
you. Your doctor can also recommend a genetic counselor who can discuss your
testing options with you in detail.
Check with your insurance company to see if BRCA1 and BRCA2 mutation testing
is covered under your plan.
Genetic counseling and testing for people at high risk is a covered
preventive service under the Affordable Care Act (ACA).