Breast cancer

Definition

Breast cancer is cancer that starts in the tissues of the breast. There are two main types of breast cancer:

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."

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.

Alternative Names

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

Over the course of a lifetime, 1 in 8 women will be diagnosed with breast cancer.

Risk factors you cannot change include:

Other risk factors include:

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.

Symptoms

Early breast cancer usually does not cause symptoms. This is why regular breast exams are important. As the cancer grows, symptoms may include:

Men can get breast cancer, too. Symptoms include breast lump and breast pain and tenderness.

Symptoms of advanced breast cancer may include:

Exams 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:

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

Treatment is based on many factors, including:

Cancer treatments may include:

Hormone therapy is prescribed to women with ER-positive breast cancer to block certain hormones that fuel cancer growth.

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.

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.

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.

Support Groups

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. 

Outlook (Prognosis)

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:

After considering all of the above, your doctor can discuss your risk of having a recurrence of breast cancer.

Possible Complications

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.

When to Contact a Medical Professional

Contact your health care provider if:

Call your health care provider if you develop symptoms after being treated for breast cancer:

Prevention

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:

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:

References

Chalasani P, Downey L, Stopeck AT. Caring for the breast cancer survivor: a guide for primary care physicians. Am J Med. 2010;123(6):489-95.

Chlebowski RT, Anderson GL, Gass M, et al. Estrogen plus progestin and breast cancer incidence and mortality in postmenopausal women. JAMA. 2010;304(15):1684-92.

Chlebowski RT, Kuller LH, Prentice RL, Stefanick ML, Manson JE, Gass M, et al. Breast cancer after use of estrogen plus progestin in postmenopausal women. N Engl J Med. 2009 Feb 5;360(6):573-87.

Cuzick J, DeCensi A, Arun B, et al. Preventive therapy for breast cancer: a consensus statement. Lancet Oncol. 2011;12(5):496-503.

Giuliano AE, Hunt KK, Ballman KV, et al. Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis: a randomized clinical trial. JAMA. 2011;305(6):569-75.

Goss PE, Ingle JN, Alés-Martínez JE, et al. Exemestane for breast-cancer prevention in postmenopausal women. N Engl J Med. 2011;364(25):2381-91.

Katz VL,Dotters D. Breast diseases: diagnosis and treatment of benign and malignantdisease.In: Lentz GM, Lobo RA,Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, PA: Elsevier Mosby; 2012:chap 15.

LaCroix AZ, Chlebowski RT, Manson JE, et al. Health outcomes after stopping conjugated equine estrogens among postmenopausal women with prior hysterectomy: a randomized controlled trial. JAMA. 2011 Apr 6;305(13):1305-14.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Breast cancer. Version3.2012. Available at: http://www.nccn.org/professionals/physician_gls/pdf/breast.pdf. Accessed November 16, 2012.

Warner E. Clinical practice. Breast-cancer screening. N Engl J Med. 2011 Sep 15;365(11):1025-32.


Review Date: 11/17/2012
Reviewed 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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