A: Giving estrogen to someone with a history of breast cancer can encourage tumor growth. For a woman who has a family history of breast cancer, you definitely want to be cautious with it, and ensure you have a practitioner who is very knowledgeable in your health history, as well as dosing and prescribing hormone replacements, to guide you.
I would also check out the book Estrogen Fix by Mache Seibel, which talks about how there's a window of opportunity, right around the time when you are perimenopausal, when estrogen is beneficial. Then after that, it becomes problematic. As such, I encourage you to take a look at that book and do some further digging.