Here are some statistics in regard to how family history and BRCA genetic mutations elevate the risk for breast cancer.
First, some information about breast cancer rates:
In the United States, 1 in 8 women will develop BC during their lifetime (approx. 12%).
Having a family history of BC in a first-degree relative makes a woman's risk 1.5-2 times higher. Having two first degree relatives with BC makes a woman's risk 4-6 times higher.
The risk of breast cancer in carriers of BRCA1 mutation is estimated to be 36-87%. Lifetime breast cancer risk for carriers of BRCA2 is 45-84%.
That really depends on whether or not she has a BRCA mutation. First of all, because BC is prevalent in the family, her risk is higher. If there is a BRCA mutation, depending on what type of mutation, it could be as high as as 85% or so.
Best course of action would be to get to a genetic counselor who specializes in BRCA mutations to find out exactly which step to take next. They can be found at most major breast cancer centers in the states.
The blood test is expensive but if the counselor recommends it, it will be covered by insurance, amounts to be covered based on insurance company guidelines and policy.
If BRCA mutation exists, it's not just BC that she will be at high risk for so it's important to find out.