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About 5% to 10 % of Breast Cancers

The genes we inherited may have mutated from one generation to the next, thus increasing the risk of developing breast cancer. However only a small percentage of breast cancers, that is about 5% to 10%, are attributable to a known genetic mutation.


With regards to breast cancer, mutations in genes such as BRCA1 and BRCA2 make some women more susceptible to be affected by breast cancer. Due to the effects of their mutations, these genes can no longer carry out their normal function and thus contribute to the appearance of tumours. However these genetic mutations are rare.

Studies have revealed that women carriers of BRCA1 and BRCA2 gene mutations have a high risk of developing breast cancer. The disease develops in 50% to 80% of these women, especially when they are young or before they reach menopause. Moreover, if the cancer appears in one breast, the risk of it developing in the other increases.

Women of eastern European and Ashkenazi Jewish descent are at a higher risk of developing breast cancer, as a greater number of these women than others have mutated BRCA genes.

Other Genetic Disorders

Other rare hereditary genetic disorders can also increase the risk of breast cancer: Li-Fraumeni syndrome, ataxia telangiectasia, Cowden syndrome, Peutz-Jeghers syndrome, and the CHEK2 gene mutation.

If you are concerned about a risk of breast cancer linked to hereditary mutations, don’t hesitate to discuss it with your doctor, to evaluate your risk or to proceed with genetic testing.