Breast Cancer

Breast cancer will affect 1 in 8 women during their lives. Breast self-examination and routine screening can help find and treat breast cancer in its early, most treatable stages.

Breast Cancer Overview

Reviewed: May 19, 2014

Breast cancer is cancer that forms in the cells of the breast. It is the most common cancer diagnosed in women in the United States, but it can occur in men.

Most lumps found in the breast are not cancerous. They are usually caused by fibrosis or cysts.

The most common type of breast cancer is ductal carcinoma, which begins in the cells of the ducts within the breasts. Breast cancer can also begin in the cells of the lobules and in other tissues in the breast. Invasive breast cancer is breast cancer that has spread from where it began in the ducts or lobules to surrounding tissue.

Surgery, radiation therapy, chemotherapy, and hormone therapy are often used to treat breast cancer.

Substantial support for breast cancer awareness and research funding has helped improve the screening and diagnosis and advances in the treatment of breast cancer. Breast cancer survival rates have increased, and the number of deaths due to this disease has been steadily declining, which is due to a number of factors including earlier detection, personalized approaches to treatment, and a better understanding of the disease.

Breast Cancer Symptoms

Signs and symptoms of breast cancer may include:

  • A breast lump or thickening that feels different from the surrounding tissue
  • Bloody discharge from the nipple
  • Change in the size, shape or appearance of a breast
  • Changes to the skin over the breast, such as dimpling
  • A newly inverted nipple
  • Peeling, scaling or flaking of the pigmented area of skin surrounding the nipple (areola) or breast skin
  • Redness or pitting of the skin over your breast, like the skin of an orange

Breast Cancer Causes

The cause of breast cancer is not entirely clear. Cancer occurs when some breast cells begin growing abnormally. These cells divide more rapidly than healthy cells do and continue to accumulate, forming a lump or mass. The cells may spread (metastasize) through your breast to your lymph nodes or to other parts of your body.

Breast cancer most often begins with cells in the milk-producing ducts (invasive ductal carcinoma). Breast cancer may also begin in the glandular tissue called lobules (invasive lobular carcinoma) or in other cells or tissue within the breast.

Hormonal, lifestyle, and environmental factors may increase the risk of getting breast cancer, but it is not clear why some people who have no risk factors develop cancer and other people with risk factors never do. Breast cancer is likely caused by a complex interaction of genetic makeup and environment. An estimated 5 to 10 percent of breast cancers are linked to gene mutations passed through generations of a family, but there are several inherited mutated genes that can increase the likelihood of breast cancer. The most common are breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2), both of which significantly increase the risk of both breast and ovarian cancer.

Other factors that are associated with an increased risk of breast cancer include:

  • Being female. Women are much more likely than men are to develop breast cancer.
  • Increasing age. Your risk of breast cancer increases as you age.
  • A personal history of breast cancer. If you have had breast cancer in one breast, you have an increased risk of developing cancer in the other breast.
  • A family history of breast cancer. If your mother, sister, or daughter was diagnosed with breast cancer, particularly at a young age, your risk of breast cancer is increased.
  • Radiation exposure. If you received radiation treatments to your chest as a child or young adult, your risk of breast cancer is increased.
  • Obesity. Being obese increases your risk of breast cancer.
  • Beginning your period at a younger age. Beginning your period before age 12 increases your risk of breast cancer.
  • Beginning menopause at an older age. If you began menopause at an older age, you're more likely to develop breast cancer.
  • Having your first child at an older age. Women who give birth to their first child after age 35 may have an increased risk of breast cancer.
  • Having never been pregnant. Women who have never been pregnant have a greater risk of breast cancer than do women who have had one or more pregnancies.
  • Postmenopausal hormone therapy. Women who take hormone therapy medications that combine estrogen and progesterone to treat the signs and symptoms of menopause have an increased risk of breast cancer. The risk of breast cancer decreases when women stop taking these medications.
  • Drinking alcohol. Drinking alcohol increases the risk of breast cancer.

Breast Cancer Diagnosis

Tests and procedures used to screen for and diagnose breast cancer include:

  • Breast exam. Your doctor will feel both of the breasts and lymph nodes in the armpit, feeling for any lumps or other abnormalities.
  • Mammogram. A mammogram is an X-ray of the breast. Mammograms are commonly used to screen for breast cancer. If an abnormality is detected on a screening mammogram, your doctor may recommend a diagnostic mammogram to further evaluate that abnormality.
  • Breast ultrasound. Ultrasound uses sound waves to produce images of structures deep within the body. Ultrasound may help distinguish between a solid mass and a fluid-filled cyst. An ultrasound is often obtained as part of the examination of a new lump.
  • Removing a sample of breast cells for testing (biopsy). Biopsy samples are sent to a laboratory for analysis where experts determine whether the cells are cancerous. A biopsy sample is also analyzed to determine the type of cells involved in the breast cancer, the aggressiveness (grade) of the cancer, and whether the cancer cells have hormone receptors or other receptors that may influence your treatment options.
  • Breast magnetic resonance imaging (MRI). An MRI machine uses a magnet and radio waves to create pictures of the interior of your breast.

Living With Breast Cancer

If you have or have had breast cancer, you can take steps to manage the stress that accompanies the diagnosis:

  • Learn about breast cancer so you can make informed decisions about your care.
  • Have a schedule of follow-up tests and go to each appointment. 
  • Take care of yourself so that you are ready to fight cancer. This includes eating a healthy that includes plenty of fruits, vegetables and whole grains, exercising for at least 30 minutes most days of the week, and getting enough sleep so that you wake feeling rested.
  • Accept help and support from family and friends.
  • Talk with other cancer survivors or attend support groups. 

Breast Cancer Treatments

The treatments for breast cancer are based on the type of cancer, the stage of the cancer, whether the cancer is sensitive to hormones, your overall health, and your preferences. Most women undergo surgery for breast cancer and also receive additional treatment before or after surgery, such as chemotherapy, hormone therapy, targeted drug therapy, or radiation.

Surgeries used to treat breast cancer may involve removing just the cancer (lumpectomy), removing the entire breast (mastectomy), and/or removing lymph nodes involved in the cancer (sentinel node biopsy or axillary lymph node dissection).

Radiation therapy uses high-powered beams of energy, such as X-rays, to kill cancer cells. Radiation therapy is typically done using a large machine that aims the energy beams at your body (external beam radiation). But radiation can also be done by placing radioactive material inside your body (brachytherapy).

Chemotherapy uses drugs to destroy cancer cells. If your cancer has a high risk of returning or spreading to another part of your body, your doctor may recommend chemotherapy to decrease the chance that the cancer will recur. Chemotherapy is sometimes given before surgery in women with larger breast tumors. The goal is to shrink a tumor to a size that makes it easier to remove with surgery. Chemotherapy is also used in women whose cancer has already spread to other parts of the body. Chemotherapy may be recommended to try to control the cancer and decrease any symptoms the cancer is causing.

Common chemotherapy drugs used in breast cancer include:

Hormone therapy is often used to treat breast cancers that are sensitive to hormones. Doctors sometimes refer to these cancers as estrogen receptor positive (ER positive) and progesterone receptor positive (PR positive) cancers.

Hormone therapy can be used after surgery or other treatments to decrease the chance of your cancer returning. If the cancer has already spread, hormone therapy may shrink and control it.

Treatments that can be used in hormone therapy include:

  • Selective estrogen receptor modulator (SERM) medications, which block estrogen from attaching to the estrogen receptor on the cancer cells and slow the growth of tumors and killing tumor cells. SERMs include tamoxifen, raloxifene (Evista) and toremifene (Fareston).
  • Aromatase inhibitors, which block the action of an enzyme that converts androgens (male sex hormones) in the body into estrogen (female sex hormones). These drugs are effective only in postmenopausal women. Aromatase inhibitors include anastrozole (Arimidex), letrozole (Femara) and exemestane (Aromasin).
  • Fulvestrant (Faslodex) blocks estrogen receptors on cancer cells and signals the cell to destroy the receptors. Fulvestrant is used in postmenopausal women.

Targeted drug treatments attack specific abnormalities such as protein growth within cancer cells. Targeted drugs used to treat breast cancer include: ado-trastuzumab (Kadcyla), bevacizumab (Avastin), lapatinib (Tykerb), pertuzumab (Perjeta), and trastuzumab (Herceptin).