This graph, comparing the cumulative risk of breast cancer in subgroups of the high risk population and in the general population illustrates the two main challenges of screening very high risk women.
The first challenge is the very young age at which we have to start screening. A 30 year old BRCA1 mutation carrier has about the same annual risk of breast cancer as a 60 year old woman in the general population.
The 2nd challenge is the very high sensitivity required of the screening regimen. Of 100 woman in the general population getting screening mammography with 80% sensitivity, only 2 will have a breast cancer missed by screening before they reach age 70. But 13 of 100 BRCA1 carriers will have a cancer missed by screening, even if screening mammography were equally sensitive for them, and it isn’t.