Skip to content

Breast Cancer Health Center

Font Size

Breast Cancer Screening (PDQ®): Screening - Patient Information [NCI] - General Information About Breast Cancer

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.

The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts.
cdr0000415520.jpg
Anatomy of the female breast. The nipple and areola are shown on the outside of the breast. The lymph nodes, lobes, lobules, ducts, and other parts of the inside of the breast are also shown.

Each breast also contains blood vessels and lymph vessels. The lymph vessels carry an almost colorless fluid called lymph. Lymph vessels lead to organs called lymph nodes. Lymph nodes are small bean-shaped structures that are found throughout the body. They filter substances in lymph and help fight infection and disease. Clusters of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.

See the following PDQ summaries for more information about breast cancer:

  • Breast Cancer Prevention
  • Breast Cancer Treatment
  • Genetics of Breast and Ovarian Cancer

Breast cancer is the second leading cause of death from cancer in American women.

Women in the United States get breast cancer more than any other type of cancer except for skin cancer. Breast cancer is second only to lung cancer as a cause of cancer death in women.

Breast cancer occurs more often in white women than in black women. However, black women are more likely than white women to die from the disease.

Breast cancer occurs in men also, but the number of cases is small.

Health history can affect the risk of breast cancer.

Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk for breast cancer. Risk factors for breast cancer include:

  • Having certain gene mutations (changes), such as in the BRCA1 or BRCA2 genes.
  • Menstruating at an early age.
  • Older age at first birth or never having given birth.
  • A personal history of invasive breast cancer, ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), or benign (noncancer) breast disease.
  • A family history (first degree relative, such as a mother, daughter or sister) with breast cancer.
  • Treatment with radiation therapy to the breast/chest.
  • Breast tissue that is dense on a mammogram.
  • Taking hormones such as estrogen and progesterone for symptoms of menopause.
  • Obesity.
  • Not getting enough exercise.
  • Drinking alcoholic beverages.
  • Being white.

NCI's Breast Cancer Risk Assessment Tool uses a woman's risk factors to estimate her risk for breast cancer during the next five years and up to age 90. This online tool is meant to be used by a health care provider. For more information on breast cancer risk, call 1-800-4-CANCER.

    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Public Information from the National Cancer Institute

    Last Updated: September 04, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
    1
    Next Article:

    Today on WebMD

    Breast Cancer Overview
    From self-exams and biopsies to reconstruction, we’ve got you covered.
    Dealing with breast cancer
    Get answers to your questions.
     
    woman having mammogram
    Experts don’t agree on all fronts, but you can be your own advocate.
    woman undergoing breast cancer test
    Many women worry. But the truth? Most abnormalities aren’t breast cancer.
     
    Breast Cancer Treatments Improving
    VIDEO
    Resolved To Quit Smoking
    SLIDESHOW
     
    Woman getting mammogram
    Article
    Screening Tests for Women
    SLIDESHOW
     
    ovarian cancer overview slideshow
    SLIDESHOW
    serious woman
    Article
     
    what is your cancer risk
    HEALTH CHECK
    10 Ways to Revitalize Slideshow
    SLIDESHOW