Breast Cancer

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Causes, Risk Factors, and Prevention TOPICS

Do we know what causes breast cancer?



Some genes control when our cells grow, divide into new cells, and die. Genes that speed up cell division are called oncogenes. Others that slow down cell division, or cause cells to die at the right time, are called tumor suppressor genes. Certain changes (mutations) in DNA that “turn on” oncogenes or “turn off” tumor suppressor genes can cause normal breast cells to become cancerous.

Inherited gene mutations

Certain inherited DNA mutations can dramatically increase the risk for developing certain cancers and are responsible for many of the cancers that run in some families. For example, the BRCA genes (BRCA1 and BRCA2) are tumor suppressor genes. A mutation in one of these genes can be inherited from a parent. When one of these genes are mutated, it no longer suppresses abnormal growth, and cancer is more likely to develop.



Acquired gene mutations


Tests to spot acquired gene changes may help doctors more accurately predict the outlook for some women with breast cancer. For example, tests can identify women whose breast cancer cells have too many copies of the HER2 oncogene. These cancers tend to be more aggressive. At the same time, drugs have been developed that specifically target these cancers and improve outcomes for patients.


Last Medical Review: 09/25/2014
Last Revised: 01/15/2016