I hope you are already starting mammograms because of your family history. And best wishes for your sister.
Hi.
Risk factors for the development of breast cancer include age, reproductive history, family and personal history of breast cancer, and exposures to specific carcinogens. You have a high risk of developing breast cancer based on the strong family history. The risk of developing breast cancer by age 70 is about 45% to 87% for those with BRCA1 mutations while it is about 26% to 84% for those with BRCA2 mutations.
Since you are at risk, you may undergo genetic testing. It is very important also to modify lifestyle, exercise, and have a regular consultation with your doctor.
Hope this helps.