Breast cancer is cancer that starts in the tissues of the breast. There are two main types of breast cancer:
- Ductal carcinoma starts in the tubes (ducts) that move milk from the breast to the nipple. Most breast cancers are of this type.
- Lobular carcinoma starts in the parts of the breast, called lobules, which produce milk.
In rare cases, breast cancer can start in other areas of the breast.
Breast cancer can be invasive or noninvasive. Invasive means it has spread from the milk duct or lobule to other tissues in the breast. Noninvasive means it has not yet invaded other breast tissue. Noninvasive breast cancer is called "in situ."
- Ductal carcinoma in situ (DCIS), or intraductal carcinoma, is breast cancer in the lining of the milk ducts that has not yet invaded nearby tissues. It may progress to invasive cancer if untreated.
- Lobular carcinoma in situ (LCIS) is a marker for an increased risk of invasive cancer in the same or both breasts.
Many breast cancers are sensitive to the hormone estrogen. This means that estrogen causes the breast cancer tumor to grow. Such cancers have estrogen receptors on the surface of their cells. They are called estrogen receptor-positive cancer or ER-positive cancer.
Some women have HER2-positive breast cancer. HER2 refers to a gene that helps cells grow, divide, and repair themselves. When cells (including cancer cells) have too many copies of this gene, they grow faster. In the past, women with HER2-positive breast cancer have a more aggressive disease. They have a higher risk that the disease will return (recur) than in women who do not have this type. This may be changing with specifically targeted treatments against HER2.
Cancer - breast; Carcinoma - ductal; Carcinoma - lobular; DCIS; LCIS; HER2-positive breast cancer; ER-positive breast cancer; Ductal carcinoma in situ; Lobular carcinoma in situ
Causes, incidence, and risk factors
Over the course of a lifetime, 1 in 8 women will be diagnosed with breast cancer.
Risk factors you cannot change include:
- Age and gender -- Your risk of developing breast cancer increases as you get older. Most advanced breast cancer cases are found in women over age 50. Men can slo get breast cancer. But they are 100 times less likely than women to get breast cancer.
- Family history of breast cancer -- You may also have a higher risk of breast cancer if you have a close relative who has had breast, uterine, ovarian, or colon cancer. About 20 - 30% of women with breast cancer have a family history of the disease.
- Genes -- Some people have genetic mutations that make them more likely to develop breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that protect you from cancer. If a parent passes you a defective gene, you have an increased risk of breast cancer. Women with one of these defects have up to an 80% chance of getting breast cancer sometime during their life.
- Menstrual cycle -- Women who got their periods early (before age 12) or went through menopause late (after age 55) have an increased risk of breast cancer.
Other risk factors include:
- Alcohol use -- Drinking more than 1 - 2 glasses of alcohol a day may increase your risk of breast cancer.
- Childbirth -- Women who have never had children or who had them only after age 30 have an increased risk of breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces your risk of breast cancer.
- DES -- Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to the women in the 1940s - 1960s.
- Hormone replacement therapy (HRT) -- You have a higher risk of breast cancer if you have received hormone replacement therapy with estrogen for several years or more.
- Obesity -- Obesity has been linked to breast cancer, although this link is not completely understood. The theory is that obese women produce more estrogen. This can fuel the development of breast cancer.
- Radiation -- If you received radiation therapy as a child or young adult to treat cancer of the chest area, you have a very high risk of developing breast cancer. The younger you started such radiation and the higher the dose, the higher your risk. This is especially true if the radiation was given during breast development.
Breast implants, using antiperspirants, and wearing underwire bras do not raise the risk of breast cancer. There is also no evidence of a direct link between breast cancer and pesticides.
Early breast cancer usually does not cause symptoms. This is why regular breast exams are important. As the cancer grows, symptoms may include:
- Breast lump or lump in the armpit that is hard, has uneven edges, and usually does not hurt
- Change in the size, shape, or feel of the breast or nipple -- for example, you may have redness, dimpling, or puckering that looks like the skin of an orange
- Fluid coming from the nipple -- may be bloody, clear to yellow, green, and look like pus
Men can get breast cancer, too. Symptoms include breast lump and breast pain and tenderness.
Symptoms of advanced breast cancer may include:
- Bone pain
- Breast pain or discomfort
- Skin ulcers
- Swelling of in the armpit (next to the breast with cancer)
- Weight loss
Signs and tests
The doctor will ask you about your symptoms and risk factors. Then the doctor will perform a physical exam. The exam includes both breasts, armpits, and the neck and chest area.
Tests used to diagnose and monitor patients with breast cancer may include:
- Breast MRI to help better identify the breast lump or evaluate an abnormal change on a mammogram
- Breast ultrasound to show whether the lump is solid or fluid-filled
- Breast biopsy, using methods such as needle aspiration, ultrasound-guided, stereotactic, or open
- CT scan to check if the cancer has spread
- Mammography to screen for breast cancer or help identify the breast lump
- PET scan to check if the cancer has spread
- Sentinel lymph node biopsy to check if the cancer has spread to the lymph nodes
If your doctor learns that you do have breast cancer, more tests will be done. This is to check if the cancer has spread. This is called staging. Staging helps guide future treatment and follow-up. It also gives you an idea of what to expect in the future.
Breast cancer stages range from 0 to IV. The higher the staging number, the more advanced the cancer.
Treatment is based on many factors, including:
- Type and stage of the cancer
- Whether the cancer is sensitive to certain hormones
- Whether the cancer overproduces (overexpresses) a gene called HER2/neu
Cancer treatments may include:
- Chemotherapy medicines to kill cancer cells
- Radiation therapy to destroy cancerous tissue
- Surgery to remove cancerous tissue -- a lumpectomy removes the breast lump; mastectomy removes all or part of the breast and possible nearby structures
Hormone therapy is prescribed to women with ER-positive breast cancer to block certain hormones that fuel cancer growth.
- An example of hormonal therapy is the drug tamoxifen. This drug blocks the effects of estrogen. Estrogen allows breast cancer cells to survive and grow. Most women with estrogen-sensitive breast cancer benefit from this drug.
- Another class of hormone therapy medicines is called aromatase inhibitors. Medicines such as exemestane (Aromasin) work as well or even better than tamoxifen in postmenopausal women with breast cancer. Aromatase inhibitors block estrogen from being made in the body.
Targeted therapy is also called biologic therapy. It uses special anticancer drugs that target certain changes in a cell that can lead to cancer. One such drug is trastuzumab (Herceptin). It may be used for women with HER2-positive breast cancer.
Cancer treatment can be local or systemic.
- Local treatments involve only the area of disease. Radiation and surgery are forms of local treatment.
- Systemic treatments affect the entire body. Chemotherapy is a type of systemic treatment.
Most women receive a combination of treatments. For women with stage I, II, or III breast cancer, the main goal is to treat the cancer and prevent it from returning (curing). For women with stage IV cancer, the goal is to improve symptoms and help them live longer. In most cases, stage IV breast cancer cannot be cured.
- Stage 0 and DCIS -- Lumpectomy plus radiation or mastectomy is the standard treatment. Doctors do not quite agree on how best to treat DCIS.
- Stage I and II -- Lumpectomy plus radiation or mastectomy with some sort of lymph node removal is the standard treatment. Hormone therapy, chemotherapy, and biologic therapy may also be recommended after surgery.
- Stage III -- Treatment involves surgery, possibly followed by chemotherapy, hormone therapy, and biologic therapy.
- Stage IV -- Treatment may involve surgery, radiation, chemotherapy, hormone therapy, or a combination of these treatments.
After treatment, some women will continue to take medicines such as tamoxifen for a time. All women will continue to have blood tests, mammograms, and other tests after treatment.
Women who have had a mastectomy may have reconstructive breast surgery. This will be done either at the time of mastectomy or later.
You can ease the stress of illness by joining a cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.
New, improved treatments are helping persons with breast cancer live longer. Even with treatment, though, breast cancer can spread to other parts of the body. Sometimes, cancer returns even after the entire tumor has been removed and nearby lymph nodes are found to be cancer-free.
How well you do after being treated for breast cancer depends on many things. The more advanced your cancer, the poorer the outcome. Other factors used to determine the risk of recurrence and the likelihood of successful treatment include:
- Location of the tumor and how far it has spread
- Whether the tumor is hormone receptor-positive or -negative
- Tumor markers, such as HER2
- Gene expression
- Tumor size and shape
- Rate of cell division or how quickly the tumor is growing
After considering all of the above, your doctor can discuss your risk of having a recurrence of breast cancer.
You may experience side effects or complications from cancer treatment. For example, radiation therapy may cause temporary swelling of the breast (lymphedema), and aches and pains around the area.
Lymphedema may start 6-8 weeks after surgery or after radiation treatment for cancer. It can also start slowly after cancer treatment is over. You may not notice symptoms until 18-24 months after treatment. Sometimes it can take years to develop.
Ask your doctor about the side effects you may have during treatment.
Calling your health care provider
Contact your health care provider if:
- You have a breast or armpit lump
- You have nipple discharge
Call your health care provider if you develop symptoms after being treated for breast cancer:
- Nipple discharge
- Rash on the breast
- New lumps in the breast
- Swelling in the area
- Pain, especially chest pain, abdominal pain, or bone pain
Tamoxifen is approved for breast cancer prevention in women aged 35 and older who are at high risk. Discuss this with your doctor.
Women at very high risk of breast cancer may consider preventive (prophylactic) mastectomy. This is surgery to remove the breasts before breast cancer is ever diagnosed. Possible candidates include:
- Women who have already had one breast removed due to cancer
- Women with a strong family history of breast cancer
- Women with genes or genetic mutations that raise their risk of breast cancer (such as BRCA1 or BRCA2)
Your doctor may do a total mastectomy to reduce your risk of breast cancer. This may reduce, but does not eliminate the risk of breast cancer.
Many risk factors, such as your genes and family history, cannot be controlled. But making healthy lifestyle changes may reduce your overall chance of getting cancer. This includes eating health foods:
- Choose foods and portion sizes that promote a healthy weight
- Choose whole grains instead of refined grain products
- Eat more fruits and vegetables each day
- Limit processed and red meat in the diet
- Limit alcohol consumption to one drink per day (women at high risk of breast cancer should not drinking alcohol at all)
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Last reviewed 11/17/2012 by Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.
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