Alternative Names
cancer of the breast
What is Breast Cancer? Breast Cancer Symptoms & Characteristics
The breast is a collection of fatty tissue and glands (or lobules) that lie between the chest wall and the skin. Many lobules make up a lobe and there are about 15 to 20 lobes in each breast. In women, the glands in the breast make milk after a baby is born. Lymph vessels and blood vessels can also be found in the breast.
Symptoms of breast cancer may include:
- a lump in the breast
- a change in size or shape of the breast
- nipple discharge
Breast Cancer Management & Treatment
Breast cancer treatment may include: tumor removal (lumpectomy), radiation, removal of the breast tissue (mastectomy), chemotherapy and hormone therapy depending on the type and stage of cancer.
How Common Is Breast Cancer? Breast Cancer Statistics
About 1 in 8 women will be diagnosed with breast cancer in their lifetime.
Breast cancer is the second leading cause of cancer death in American women behind lung cancer.
Breast Cancer Causes & Risk Factors
Many risk factors have been proposed to contribute to breast cancer risk in females, some of which include:
- Early menstruation
- Late menopause
- Being overweight
- Lack of exercise
- Alcohol consumption
- Smoking
- Using hormone replacement therapy
- Taking birth control pills
- Not having children or having your first child after age 35
- Never breast feeding
- Exposure to diethylstilbestrol (DES) in utero
- Increasing age
- Having a family history of breast and/or associated cancers (see below)
Some of these risk factors are debated and currently under further investigation.
Breast Cancer Inheritance & Family History
Cancer is a multifactorial condition, which means it involves a combination of genetic, lifestyle and environmental factors. Most cases of breast cancer are not inherited and occur sporadically. Breast cancer is more likely to be hereditary when there is a family history of early-onset breast cancer (diagnosed under age 50), ovarian cancer, two or more primary breast cancers in the same person, male breast cancer, and multiple cases of breast, ovarian and/or pancreatic cancer.
Genetic breast cancer predisposition can be broken down into different categories including: Hereditary Cancer Syndromes, Genetic Conditions, and Single Nucleotide Polymorphisms (SNPs).
Hereditary Cancer Syndromes:
It is currently believed an estimated 5% to 10% of all breast cancers are caused by a hereditary cancer syndrome.
- A hereditary cancer syndrome is caused by an inherited gene mutation that increases the chance to develop one or more types of cancer. Several different hereditary cancer syndromes have been identified.
Hereditary breast and ovarian cancer syndrome is the most common hereditary cancer syndrome associated with breast cancer.
The two genes associated with hereditary breast and ovarian cancer syndrome are BRCA1 and BRCA2.
Women who have a mutation in either of these genes, have an estimated 60% to 80% lifetime risk to develop breast cancer and an estimated 20% to 40% lifetime risk to develop ovarian cancer depending on if there is a family history of ovarian cancer, breast and ovarian cancer, or breast cancer alone.
Males with a mutation in either of the BRCA1 or BRCA2 genes have a lower breast cancer risk, but it is still higher than the general population.
- The BRCA1 gene is located on chromosome 17 at the location q21. Males who have a BRCA1 mutation have a prostate cancer risk three times higher than the general population.
- Three specific mutations in the BRCA1 and BRCA2 genes are more common in people of Ashkenazi (eastern and central European) Jewish ancestry. These mutations are187delAG (BRCA1), 5385insC (BRCA1), and 6174delT (BRCA2). About 1 in 40 Ashkenazi Jewish people have one of these mutations.
- Specific mutations in the BRCA1 and BRCA2 genes have also found in the people of Icelandic, Norwegian, and Dutch ancestry. Particular genetic variations occur more frequently in all of these ethnic groups because they have shared ancestry over many generations.
There are a number of hereditary cancer syndromes that confer an elevated risk to develop breast cancer along with even higher risks to develop other types of cancers. Some of the other hereditary cancer syndromes associated with breast cancer include:
- Hereditary diffuse gastric cancer (HDGC)
Many other genes have been associated with susceptibility to breast cancer as well:
- One gene, RAD51 (15q15.1), may cause susceptibility to breast cancer, especially in combination with a BRCA1 or BRCA2 mutation
- A specific variant of the CHEK2 gene (called 1100delC) has also been associated with breast cancer
Genetic Conditions:
People with certain genetic conditions are at increased risk to develop some types of cancer. Some of the common genetic conditions that are associated with breast cancer include:
Single Nucleotide Polymorphisms (SNPs):
SNPs are small variations in a single "letter" of DNA that can be found throughout our entire genetic make-up. Some researchers have proposed that specific SNPs may cause susceptibility to breast cancer in some people.
The contributions of individual SNPs to breast cancer risk are considered minor in comparison to high risk mutations in the BRCA1/BRCA2 genes or other hereditary cancer syndromes.
Research is also focusing on how these SNPs taken together further modify breast cancer risk. Further research is needed to replicate study findings across different ethnic groups and clearly establish associations.
Breast Cancer Tests & Diagnosis
Clinical tests and procedures used to diagnose breast cancer may include:
- A specialized X-ray of the breast called a mammogram
- An ultrasound of the breast
- Magnetic resonance imaging (MRI) of the breast
- A biopsy of breast tissue
Cancer predisposition testing for hereditary breast and ovarian cancer syndrome is available online (over the internet) as well as through an in person genetic consultation for people who are considered at risk. Cancer predisposition testing for other hereditary cancer syndromes and clinical genetic testing for the genetic conditions associated with breast cancer may be available as well.
In a cancer genetic consultation, a trained genetic professional will discuss the risks, benefits, and limitations of all genetic testing options, as well as any possible screening and preventative measures.
Go to the Tests tab to link to online providers, compare providers and read provider reviews.
- Whenever possible, genetic testing should be performed on the person in the family who is most likely to have a BRCA1 and BRCA2 mutation or other hereditary cancer syndrome, and who is less likely to have developed sporadic (non-inherited) breast cancer. If a mutation is found, genetic testing can then be offered to non-affected family members.
- Testing for people of Ashkenazi Jewish descent may be initially performed by looking for the three common mutations in the BRCA1 and BRCA2 genes. If no mutation is found, more extensive testing of these genes may be offered.
- Positive genetic testing does not mean that breast cancer is inevitable. If a woman does have a mutation, there are some steps she may want to take. There are the options of more rigorous screening, preventive medications, as well as prophylactic oophorectomies (removal of the ovaries) or prophylactic mastectomies (removal of the breasts) to decrease cancer risk.
- Conversely, negative genetic testing does not mean that a person will never develop breast cancer. In some cases, negative genetic testing may not even lower breast cancer risk if other factors, like a strong family history, are still present.
- All genetic testing results should be provided and explained in context of the each individual's unique personal and family histories.
- There is considerable debate and concern regarding testing of at-risk individuals younger than age 18 years old for adult-onset conditions (including BRCA1 or BRCA2 cancer-predisposing mutations). Such testing is typically unavailable. The American Society of Human Genetics in conjunction with the American College of Medical Genetics as well as the National Society of Genetic Counselors have issued statements regarding this type of testing:
Informational genetic testing for breast cancer susceptibility is available online (over the internet). Go to the Tests tab to link to the best online providers, compare providers and read provider reviews.
The decision to have genetic testing is personal and should always be discussed with trained medical professional.
Breast Cancer Prevention & Related Issues
- Talk to your doctor about when to receive clinical breast exams and mammograms
- Avoid excessive alcohol consumption
- Maintain a healthy weight
- Preventive medications (chemoprevention) and surgeries, such as prophylactic mastectomy (removal of healthy breasts) and prophylactic oophorectomy (removal of healthy ovaries), may be offered to women at high risk
- Genetic testing for mutations in the BRCA1 and BRCA1 genes may be offered to women at high risk
Breast Cancer Support & More Information
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Breast Cancer Sources