Sisters with breast cancer

I have been diagnosed with DCIS and waiting on surgery, hopefully only a lumpectomy followed by radiation. I am 50, My oldest sister was diagnosed at 57 and passed away at 59, 3 years ago.. My younger sister was diagnosed about a month later at 47 and has had a mastectomy and still having treatment. Turns out my grandmother on my dads side,who I knew nothing of died at 44 or 47 from breast cancer. We have not had genetic testing as yet