There is a lot of debate about the role of Estrogen exposure. It clearly contributes to breast cancer risk, not as much if you don’t have family history.
So it might be wise to Avoid long-term hormone therapy. Avoid working night shifts- it changes your hormonal balance because of lighting (light is a big factor of hormonal changes during the day). and there are a lot of estrogen-like pesticides today, it’s suspected as one of the things that raised the amount of breast cancer in modern life.
Here is a nice site that might help:
http://www.breastcancer.org/risk/