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Breast Cancer Prevention

    Avoiding risk factors and increasing protective factors may help prevent cancer.

    Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking, eating a healthy diet, and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.

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    About This PDQ Summary

    Purpose of This Summary This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of male breast cancer. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions. Reviewers and Updates This summary is reviewed regularly and updated as necessary by the PDQ Adult Treatment Editorial...

    Read the About This PDQ Summary article > >

    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.

    The following risk factors may increase the risk of breast cancer:

    Estrogen (endogenous)

    Endogenous estrogen is a hormone made by the body. It helps the body develop and maintain female sex characteristics. Being exposed to estrogen over a long time may increase the risk of breast cancer. Estrogen levels are highest during the years a woman is menstruating. A woman's exposure to estrogen is increased in the following ways:

    • Early menstruation: Beginning to have menstrual periods at age 11 or younger increases the number of years the breast tissue is exposed to estrogen.
    • Late menopause: The more years a woman menstruates, the longer her breast tissue is exposed to estrogen.
    • Late pregnancy or never being pregnant: Because estrogen levels are lower during pregnancy, breast tissue is exposed to more estrogen in women who become pregnant for the first time after age 35 or who never become pregnant.

    Hormone replacement therapy/Hormone therapy

    Hormones that are made outside the body, in a laboratory, are called exogenous hormones. Estrogen, progestin, or both may be given to replace the estrogen no longer produced by the ovaries in postmenopausal women or women who have had their ovaries removed. This is called hormone replacement therapy (HRT) or hormone therapy (HT) and may be given in one of the following ways:

    • Combination HRT/HT is estrogen combined with progesterone or progestin. This type of HRT/HT increases the risk of developing breast cancer. Women taking combination HRT/HT also may be more likely to have an abnormal mammogram. Studies show that when women stop taking estrogen combined with progesterone, the risk of getting breast cancer decreases.
    • Estrogen-only therapy may be given to women who have had a hysterectomy. Clinical trials studying whether estrogen-only therapy affects the risk of breast cancer have had mixed results. In women who have a uterus, estrogen-only therapy increases the risk of uterine cancer.
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