Breast Cancer

Cause

The exact cause of breast cancer is not known. Female hormones and increasing age play a part. The chances that you will develop breast cancer increase as you age. In the United States, about 1 in every 7 women who live to be 85 will have been diagnosed with breast cancer at some point in her life.²

Family history also plays a role in the development of breast cancer. You are more likely to have breast cancer if your mother, father, or sister has breast cancer. Also, women who carry certain genes called BRCA1 and BRCA2 are more likely to have breast and ovarian cancer. If you have a strong family history of breast or ovarian cancer, you may want to be tested for these genes. People who inherit specific changes, or mutations, in one or both of these genes have a much greater risk of developing breast and ovarian cancer.

Studies show that menopausal women who take hormone therapy with estrogen and progestin have an increased risk of breast cancer. Women who take estrogen alone may have a slightly increased risk.^{3, 4}

Many people believe that only women have breast cancer. But, although rare, about 1% of all breast cancer occurs in men. Most men who have breast cancer are older than 65, but it can appear in younger men. For this reason, any breast lump in an adult man is considered abnormal.

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Author:	Bets Davis, MFA	Last Updated: August 18, 2009
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Douglas A. Stewart, MD - Medical Oncology
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