About 5% to 10% of breast cancers are thought to be hereditary, caused by. Inherited DNA changes are passed down from parent to child.. . higher risk not only of gastrointestinal cancers, but also breast and lung cancer and ovarian tumors.
Somatic mutations in many different genes have been found in breast cancer cells. Less commonly, gene mutations present in essentially all of the body's cells increase the risk of developing breast cancer. These genetic changes, which are classified as germline mutations, are usually inherited from a parent.
Normally, every cell has 2 copies of each gene: 1 inherited from the mother and 1. . Only about 3% of breast cancers associated with BRCA mutations are .
In fact, most women with a mother or sister with breast cancer will never be. (