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Breast Cancer Risk and Prevention
There is no sure way to prevent breast cancer. But you can learn more about your risk and decide if there are things you can do that might lower the risk of having breast cancer.
What causes breast cancer?
Certain gene changes (mutations) in normal cells can affect the way the genes work. When this happens, it can cause abnormal cells to grow and lead to cancer.
We don’t know what exactly causes each case of breast cancer. But there are some known risk factors for these cancers. A risk factor is anything that affects a person’s chance of getting a disease. For example, hormones and factors such as weight, diet, and exercise seem to play a role in many cases of breast cancer.
While some of the factors that may cause gene changes are known, it’s not clear exactly how they lead to breast cancer. In some cases, these gene changes can be passed on in families. Researchers are studying this to learn more.
Gene changes that can cause breast cancer
Certain gene changes are seen more commonly in breast cancers. When doctors find gene changes in cancer cells, they may be able to use this information to diagnose and treat the cancer. There are two types of gene changes.
Inherited gene changes are gene changes that are passed on in families and are present in cells throughout the body. About 1 in 10 breast cancers are linked to inherited gene changes.
Acquired gene changes are gene changes that occur after birth. They are a more common cause of breast cancer than inherited gene changes. Acquired gene changes happen only in the cancer cells. They cause about 90% of breast cancer.
Inherited gene changes
A person with inherited gene changes is more likely to develop cancer. When certain genes are inherited, it is referred to as a family cancer syndrome. However, most cases of cancer are not caused by inherited gene changes.
High-risk inherited gene changes
Certain inherited gene changes can greatly increase the risk of developing certain cancers. These are considered “high penetrance” changes.
Examples of high penetrance genes linked to breast cancer include BRCA1 and BRCA2 . These genes block abnormal cells from growing. Changes in these genes can lead to hereditary breast and ovarian cancer syndrome. They are the most common inherited cause of breast cancer. About 1 in 2 women with changes in these genes will develop breast cancer, compared with 1 in 8 for women without BRCA gene changes.
Other high-risk genes include CDH1, PALB2, PTEN, STK11, and TP53.
Moderate-risk inherited gene changes
Some inherited gene changes moderately raise the risk of breast cancer. The risk of cancer is lower than with “high penetrance” gene changes. These genes are called “moderate penetrance” genes.
Examples of moderate penetrance genes include ATM and CHEK2. These genes repair damaged DNA. If the genes don’t work properly, cells with damaged DNA may grow and divide. This can lead to cancer.
See Breast Cancer Risk Factors You Cannot Change for more information on inherited gene changes and breast cancer.
Acquired gene changes
Acquired gene changes can happen by chance, because of something in the environment, or because of another risk factor. Many of these gene changes and exactly how they cause cancer are still unknown.
Other risk factors for breast cancer
We don't know what causes the gene changes in each case of breast cancer. But many of the risk factors for these cancers are known. Some risk factors are things you can change, such as eating a healthy diet, not smoking, taking part in physical activity, and some hormone treatments.
Other risk factors you cannot change. These include your age, ethnicity, and family history.
Can breast cancer be prevented?
There is no sure way to prevent breast cancer. But there are things you can do that might lower your risk. This can be especially helpful for people with certain risk factors for breast cancer, such as having a strong family history or certain inherited gene changes.
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- References
Developed by the P站视频 medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Cyr AE, Kennard K. Individualizing Breast Cancer Risk Assessment in Clinical Practice. Surg Oncol Clin N Am. 2023;32(4):647-661.
Henry NL, Shah PD, Haider I, Freer PE, Jagsi R, Sabel MS. Chapter 88: Cancer of the Breast. In: Niederhuber JE, Armitage JO, Dorshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa. Elsevier: 2020.
National Cancer Institute. Breast Cancer Treatment (PDQ). Accessed at https://www.cancer.gov/types/breast/hp/breast-treatment-pdq on March 18, 2026.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Breast Cancer Risk Reduction Version 1.2026 – August 29, 2025. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/breast_risk.pdf on March 18, 2026.
Last Revised: March 19, 2026
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