Gene changes and the risk of Breast and Ovarian Cancer

Most cases of breast and ovarian cancer happen by chance and are not caused by an inherited mutated gene.

However, when several members of a family have developed the same type of cancer, or when individuals develop cancer at an unusually young age (less than 50), it is natural to question whether an inherited factor is involved. About 5% of women with breast cancer have the BRCA gene mutation. Having a mutation of the BRCA1 or BRCA2 gene increases the risk of breast cancer far more than does any other known risk factor for this disease.

According to estimates of lifetime risk, about 12 percent of women (120 out of 1,000) in the general population will develop breast cancer sometime during their lives compared with about 60 percent of women (600 out of 1,000) who have inherited a harmful mutation in BRCA1 or BRCA2.